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Food and Beverage Chemistry/BiochemistryMarch 9, 2023

Physical and Oxidative Stabilization of Oil-In-Water Emulsions by Roasted Coffee Fractions: Interface- and Continuous Phase-Related Effects
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Jilu Feng
Jilu Feng
Food Quality and Design Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
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https://orcid.org/0000-0003-1626-3414
Karin Schroën
Karin Schroën
Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
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Sylvain Guyot
Sylvain Guyot
INRA UR1268 BIA, F-35653 Le Rheu, France
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Agnès Gacel
Agnès Gacel
INRA UR1268 BIA, F-35653 Le Rheu, France
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Vincenzo Fogliano
Vincenzo Fogliano
Food Quality and Design Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
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https://orcid.org/0000-0001-8786-9355
Claire C. Berton-Carabin*
Claire C. Berton-Carabin
Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
INRAE, UR BIA, F-44316 Nantes, France
*Email: [email protected]
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Journal of Agricultural and Food Chemistry

Cite this: J. Agric. Food Chem. 2023, 71, 11, 4717–4728

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https://doi.org/10.1021/acs.jafc.2c07365

Published March 9, 2023

CC-BY 4.0 .

Abstract

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Emulsions fortified with polyunsaturated fatty acids are highly relevant from a nutritional perspective; however, such products are prone to lipid oxidation. In the current work, this is mitigated by the use of natural antioxidants occurring in coffee. Coffee fractions with different molecular weights were extracted from roasted coffee beans. These components were positioned either at the interface or in the continuous phase of emulsions where they contributed to emulsion stability via different pathways. Coffee brew as a whole, and its high-molecular-weight fraction (HMWF), was able to form emulsions with good physical stability and excellent oxidative stability. When added post-homogenization to the continuous phase of dairy protein-stabilized emulsions, all coffee fractions were able to slow down lipid oxidation considerably without altering the physical stability of emulsions, though HMWF was more effective in retarding lipid oxidation than whole coffee brew or low-molecular-weight fraction. This is caused by various effects, such as the antioxidant properties of coffee extracts, the partitioning of components in the emulsions, and the nature of the phenolic compounds. Our research shows that coffee extracts can be used effectively as multifunctional stabilizers in dispersed systems leading to emulsion products with high chemical and physical stability.

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1. Introduction

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It is nowadays well-recognized that higher amounts of ω-3 polyunsaturated fatty acids should be targeted to contribute to healthier diets. (1) As a result, the food industry strives for developing ω-3-rich products, but that is far from trivial. The presence of several double bonds makes ω-3 polyunsaturated fatty acids vulnerable to oxidation, which results in quality deterioration in foods (e.g., undesirable changes in flavor, nutritional quality, and shelf life). (2,3) A strategy to counteract lipid oxidation is through the addition of antioxidants, and ideally, these should be natural antioxidants that are preferred by consumers. (4) Synthetic antioxidants, such as butylated hydroxytoluene and butylated hydroxyanisole (BHA), are known to be highly effective. Alternatively, natural antioxidants (e.g., rosemary extracts and tocopherols) have been used, but the search for natural alternatives is still very much on.

Coffee is a rich source of compounds with potent antioxidant activity, which is modulated by the coffee bean roasting process. (5) During roasting, on the one hand, natural phenolic compounds (predominantly chlorogenic acids, CGAs) present in the green coffee beans undergo chemical reactions such as isomerization, degradation, and/or oxidation, leading to a reduction of their antioxidant activity, (6) whereas on the other hand, additional antioxidant activity may be created through the formation of certain Maillard reaction products (MRPs). In particular, melanoidins that are generated during roasting of coffee beans at high temperatures and low water activity (7,8) could be of interest due to their antioxidant potential. Some MRPs (such as acrylamide, heterocyclic amines, and 5-hydroxymethylfurfural) are potentially toxic and their presence in foods should be kept as low as reasonably achievable, (9) yet this concern does not apply to melanoidins: they are not bioavailable and have positive functions within the gastrointestinal tract, similar to dietary fibers. (10) In addition, some volatile heterocyclic compounds (furans, pyrroles, and maltol) formed during roasting have also been reported as potential antioxidants. (11) The antioxidant mechanisms of coffee components were reported to be mainly related to their ability to break the radical chain reaction cascade by hydrogen donation and to chelate metal ions. (12−14)

Coffee fractions may contribute to the overall antioxidant activity of coffee in various ways. The high antioxidant activity of the high-molecular-weight fraction (HMWF) from coffee brew was attributed to melanoidins to which low-molecular-weight compounds (e.g., phenolic compounds) were bound. (12,15,16) The low-molecular-weight fraction (LMWF) from coffee brew is in itself rich in phenolic compounds that constitute 70% of the overall antioxidant capacity, (17) and the remaining effects are expected to be caused by volatile heterocyclic compounds. (18) Although the antioxidant activity (e.g., metal chelating and radical scavenging activities) of coffee fractions has been widely reported, their ability to inhibit lipid oxidation in food systems (e.g., emulsions) has not been investigated. Unfortunately, the antioxidant activity is not always a good predictor of their efficacy as antioxidants in foods. (19) This could be due to the complexity of food systems where antioxidants can be partitioned at different locations, and therefore their properties (reactivity) may vary depending on the nature of the environments present (e.g., interactions with other components).

In addition to their intrinsic chemical properties, the effect of chemically active components on lipid oxidation in emulsions largely depends on their localization (i.e., in the oil phase, aqueous phase, or at the interface). It is widely admitted that lipid oxidation initiates at the oil–water interface. (20) Adsorbed emulsifiers with antioxidant potential (interfacial antioxidants) may therefore promote good oxidative stability of emulsified lipids through various mechanisms, such as free radical scavenging, transition metal chelating, and secondary oxidation product binding. (2) On the other hand, localization away from the interface may make antioxidants less effective in mitigating the previously mentioned effects, but may still contribute through other mechanisms, e.g., binding of metal ions, therewith delaying initiation of lipid oxidation. (2) For instance, there is a large proportion of emulsifiers remaining in the continuous phase, and thus, the contribution of these non-adsorbed emulsifiers (in particular, proteins) to retard lipid oxidation could be substantial. (20)

We recently reported the ability of the HMWF from coffee brew to physically stabilize oil-in-water (O/W) emulsions, with the polysaccharide-rich fraction predominantly present at the interface. (21) Considering their emulsifying properties and well-known antioxidant activity, one can assume that certain coffee fractions could act as antioxidant emulsifiers. The current research was therefore aimed to assess the efficiency of different coffee fractions, either present at the interface or in the continuous phase, to stabilize O/W emulsions, with a particular emphasis on their ability to inhibit lipid oxidation. To achieve this, different coffee fractions (whole coffee brew, HMWF, non-defatted HMWF, and LMWF) were extracted from dark roasted arabica coffee beans. Then, they were either used to make rapeseed oil-in-water (O/W) emulsions, or added to the continuous phase of whey protein isolate (WPI)-stabilized emulsions (with minimal excess WPI remaining in the continuous phase). The physical and oxidative stability of these emulsions were monitored during storage at 40 °C.

2. Materials and Methods

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2.1. Materials

Dark roasted arabica coffee beans and rapeseed oil were obtained from a local supermarket (Wageningen, the Netherlands). Rapeseed oil was stripped with alumina powder (Alumina N, Super I, EcoChrome, MP Biomedicals, France) to remove the surface-active impurities and tocopherols. (22) WPI (88.11 ± 1.15 wt %, N × 6.25) was obtained from Davisco (Lancy, Switzerland). l-Ascorbic acid, 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 3-(2-pyridyl)-5,6-di(2-furyl)-1,2,4-triazine-5′,5″-disulfonic acid disodium salt (ferene), iron(II) sulfate heptahydrate (FeSO₄·7H₂O), CGA (#C3878), caffeic acid, p-coumaric, cumene hydroperoxide solution (80%), sodium chloride (NaCl), para-anisidine, and n-hexane were purchased from Sigma-Aldrich (Saint Louis, MO, USA). Glacial acetic acid, hydrochloric acid (37%), 2-propanol, 1-butanol, ethanol, ethylenediaminetetraacetic acid (EDTA), barium chloride dihydrate (BaCl₂·2H₂O), ammonium thiocyanate (NH₄SCN), and sodium hydroxide (NaOH) were obtained from Merck Millipore (Merck, Germany). Acetonitrile and methanol were purchased from Carlo Erba Reagents (Val de Reuil, France). Dichloromethane was obtained from Actu-All Chemicals B.V. (Oss, The Netherlands). Sodium acetate trihydrate was purchased from VMR (Radnor, PA, USA). Ferulic acid was obtained from Extrasynthèse (Genay, France). All solvents were of at least of analytical grade. Ultrapure water was obtained from a Millipore Milli-Q water purification system (Millipore Corporation, Billerica, MA, USA) and used for all experiments.

2.2. Preparation of Coffee Brew

Roasted coffee beans were ground using a Spex sample Prep 6870 cryogenic mill (Minneapolis, Minnesota, US) to pass through a 0.425 mm sieve. The ground coffee was defatted using dichloromethane (1:3, w/v) three times. Coffee brew was prepared by adding 100 g of the defatted ground coffee to 1200 mL of water at 80 °C for 20 min, followed by filtering through a filter paper (Whatman 595, Billerica, MA, US). Part of the filtrate was freeze-dried and stored at −20 °C before use, and the other part of the filtrate was used for further isolation (Section 2.3).

2.3. Isolation of HMWF, LMWF, and Non-Defatted HMWF from Coffee Brew

An aliquot of the coffee brew obtained above was subjected to ultrafiltration (10 kDa, Amicon stirred cell, Millipore Co., MA, US). The filtrate was collected and is referred to as LMWF. To the retentate, 100 mL of water was added during three washing steps, which thus became the HMWF. The HMWF was lyophilized and stored at −20 °C. To wrap up, HMWF contains all the components that cannot go through the membrane, whereas LMWF contains all the components that can.

Non-defatted HMWF was extracted similarly as HMWF, except for the defatting step with dichloromethane that was not included. Non-defatted HMWF was prepared to investigate how the defatting step and endogenous lipids affected the physical and oxidative stability of the emulsions.

2.4. Carbohydrate, Protein, and Phenolic Group Contents

The total sugar content of the different coffee fractions (coffee brew, HMWF, non-defatted HMWF, and LMWF) in aqueous medium was measured using the phenol-sulfuric acid method. (23) Nitrogen content was determined using the Dumas method (Interscience Flash EA 1112 series, Thermo Scientific, Breda, The Netherlands), and protein content was estimated using a nitrogen to protein factor of 5.5. (24) Phenolic group content was evaluated with the Folin–Ciocalteu reagent using CGA as the standard. (25)

2.5. Analysis of Unbound Phenolic Compounds by Liquid Chromatography Coupled with Diode Array Detection and Mass Spectrometry

Methanol suspensions (for coffee brew and HMWFs) or dilutions (for LMWF) of the coffee fractions were sonicated for 30 min, then diluted 2-fold with acidified water (0.1 v % formic acid), filtrated on 0.45 μm PTFE filters, and finally injected (2 μL) onto the liquid chromatography coupled with diode array detection and mass spectrometry (LC-DAD-MS) system. Separations were performed on a reverse-phase Purospher STAR Hibar HR RP18 end-capped column (150 × 2.1 mm, 3 μm, thermostated at 30 °C, Merck, Darmstadt, Germany) in a LC system that is composed of a solvent degasser (SCM1000, Thermo Scientific, Waltham, MA, USA), a binary high-pressure pump (1100 series, Agilent Technologies, Santa Clara, CA, USA) and a Surveyor autosampler thermostated at 4 °C (Thermo Scientific), and equipped with a UV–visible photodiode array detector (UV6000 LP, Thermo Scientific) and an ion trap mass spectrometer with electrospray ionization source (LCQ Deca, Thermo Scientific). The separation of phenolic compounds was performed using a gradient mixture of A (0.1% v/v formic acid in water) and B (0.1% v/v formic acid in acetonitrile) at a flow rate of 0.2 mL/min. The linear gradient elution steps were as follows: 0–3 min, 3% B; 3–21 min, 7% B; 21–27 min, 13% B; 27–41 min, 20% B; 41–51 min, 45% B; 51–53 min, 90% B; 53–56 min, 90% B, followed by washing and reconditioning of the column. UV–visible detection was performed in the 240–600 nm range. MS spectra were recorded in the full scan mode with negative ionization mode on m/z 50–2000 range. The source parameters were set as follows: spray voltage, 4.2 kV; capillary voltage, −41 V; sheath gas, 66 arbitrary units; auxiliary gas, 10 arbitrary units; and capillary temperature: 250 °C. The phenolic compounds were identified by comparison of their retention times, UV–vis spectra, and mass spectra with those of the standards, and quantified using the UV–visible spectra based on the external standards for each class of phenolic compounds. Data were analyzed using Xcalibur software (Thermo Scientific).

2.6. Analysis of Covalently Bound Phenolic Compounds

The covalently bound phenolic compounds were released by alkaline hydrolysis of HMWF, non-defatted HMWF, and coffee brew according to the method described by (26) with some modifications. Briefly, 45 mg of sample was dissolved in 3 mL of 2 M NaOH solution containing 20 mM EDTA and 2 w/v % ascorbic acid. After incubation at 30 °C for 1 h, the mixture was adjusted to pH 3.0 with 5 M HCl. The mixture was stored at 4 °C for 2 h, followed by centrifugation at 4000g and 4 °C for 10 min. The supernatant was diluted by two with methanol, filtered with a 0.45 μm PTPE filter, and injected (2 μL) into the LC-DAD-MS system for analysis as described in Section 2.5.

2.7. Interfacial Activity

The interfacial tension between the stripped rapeseed oil and different coffee fractions in water (0.01 w/v %) was measured with an automated drop volume tensiometer (Tracker, Teclis, Longessaigne, France). A rising oil drop (area: 40 mm² made with a 20-gauge needle) was immersed in an aqueous phase with the component of interest. The interfacial tension (γ) was calculated based on the shape of the droplet using the Laplace equation and measured for 7200 s at 20 °C. The results were expressed as surface pressure (π = γ₀ – γ), with γ₀ the interfacial tension between oil and water without any coffee fraction.

2.8. Antioxidant Properties

1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity of coffee fractions was determined according to the method described by (27) with a few modifications. Briefly, 1 mL of fresh DPPH solution (200 μM in ethanol) was added to 1 mL of 0.01 w/v % WPI or coffee fraction suspension/solution in water. The mixture was shaken at 20 °C in the dark for 30 min (Eppendorf ThermoMixer C, Eppendorf, Hamburg, Germany). The absorbance of the reaction mixture (A_s: 1 mL ethanol, 1 mL sample with 0.01 w/v % component) was determined at 517 nm using ethanol as the blank. The scavenged percent of DPPH radicals (%) was calculated according to eq 1.

D P P H r a d i c a l s c a v e n g i n g a c t i v i t y (%) = (1 - \frac{A_{s} - A_{b}}{A_{c}}) \times 100 %

(1)

where A_b is the absorbance of the mixture of ethanol (1 mL) and sample (1 mL, 0.01 w/v %) and A_c is the absorbance of the mixture of DPPH solution (1 mL) and water (1 mL).

Iron chelating capacity was determined using a modified version of. (28) In brief, 1 mL of 0.01 w/v % WPI or coffee fraction was mixed with a known amount of ferrous iron solution (1 mL, 5 g/L). The mixture was vortexed and left at 20 °C for 24 h and then separated using an ultrafiltration-centrifugation tube with a membrane (cutoff 10 kDa). The filtrate obtained (0.5 mL) was added to 1 mL of dissociating agent [containing 0.5 mL of 0.5 M l-ascorbic acid and 0.5 mL of 1.4 M acetic acid buffer (pH 4.5)] and 0.1 mL of 6 mM ferene solution. After 5 min, the absorbance was measured at 593 nm. The quantity of bound iron (μg per mg of the sample) was calculated using a mass balance between unbound Fe²⁺ in the filtrate and the initial Fe²⁺ content.

2.9. Emulsion Preparation

A coarse O/W emulsion containing 10 wt % stripped rapeseed oil and 90 wt % aqueous phase (with 2 wt % coffee fractions or WPI) was prepared using a rotor-stator homogenizer (Ultra-TURRAX IKA T18 basic, Germany) at 11,000 rpm for 1 min. A M-110Y Microfluidizer (equipped with a F12Y interaction chamber, Microfluidics, Massachusetts, USA) was used to further break down the coarse oil droplets to fine droplets with five passes at 800 bar. Potassium sorbate (0.2 wt %) was added to emulsions to prevent microbial spoilage. Emulsions (2 g aliquots) were partitioned in polypropylene tubes (Eppendorf,15 × 120 mm), which were then incubated in the dark at 40 °C for 7 days under rotative agitation at 2 rpm (SB3 rotator, Stuart, Staffordshire, UK).

Addition of components. Stock WPI-stabilized emulsions (with 20 wt % rapeseed oil and 1 wt % WPI in the aqueous phase) were prepared as previously described. (29) Coffee fractions suspensions, WPI solution, or water were added to the stock emulsions to achieve final concentrations of 0.5 wt % emulsifier, 10 wt % oil, and 0.125–2 w/v % excess compounds (coffee fractions or WPI) in the continuous phase. To prevent microbial growth, 0.2 wt % of potassium sorbate was added. These emulsions were incubated under the same conditions as described above.

2.10. Physical Properties of Emulsions

The physical properties of emulsions were measured immediately after emulsification and at the end of incubation at 40 °C.

The droplet size distribution was determined by static light scattering using a particle size analyzer (Mastersizer 3000, Malvern Instruments Ltd., Worcestershire, UK). The optical parameters were a dispersed phase refractive index of 1.473, a droplet absorbance of 0.01, and a continuous phase refractive index of 1.33.

Light microscopy (Carl Zeiss Axio Scope A1, Oberkochen, Germany) was used to capture the emulsion microstructure. One droplet of the emulsion was placed on a microscopic slide and covered with a coverslip. Images were taken at a magnification of 40×.

Surface charge was measured through zeta-potential using a dynamic light scattering instrument (Zetasizer Ultra, Malvern Instruments Ltd., Worcestershire, UK). Emulsions were diluted 1000-fold in water to prevent multiple scattering. The optical parameters were the same as those used for the droplet size distribution measurement. Measurements were performed at 20 °C.

2.11. Lipid Oxidation

Lipid oxidation of emulsions was evaluated by determining the primary (lipid hydroperoxides) and secondary (aldehydes) oxidation products throughout the incubation period.

Lipid hydroperoxides were measured according to a method reported by (30) with some modifications. In short, 0.3 g of emulsion was mixed with 1.5 mL of n-hexane/2-propanol (3:1, v/v). The mixture was vortexed three times for 10 s each, with 20 s intervals, followed by centrifugation at 14,600 rpm for 2 min. Then, 0.2 mL of the upper organic phase was mixed with a 2.8 mL of methanol/1-butanol (2:1, v/v) and 30 μL of thiocyanate/ferrous iron solution (1:1, v/v). After 20 min, the absorbance of the sample was measured at 510 nm using a DU 720 UV–visible spectrophotometer (Beckman Coulter, Woerden, the Netherlands). The lipid hydroperoxide concentration was calculated using a cumene hydroperoxide standard curve.

Aldehydes were measured through the para-anisidine value (pAV) according to the AOCS Official Method CD 18–90. (31) In brief, 2 g of emulsion was mixed with 5 mL of n-hexane/2-propanol (3:1, v/v) and 1 mL of saturated sodium chloride solution. The mixture was vortexed three times for 10 s with 20 s intervals and centrifuged at 4000 rpm for 8 min. The absorbance of the upper hexane layer (A_b) was measured at 350 nm using hexane as a blank. Then, 1 mL of this hexane phase was mixed with 0.2 mL of para-anisidine solution (0.25 w/v % in acetic acid). After 10 min, the absorbance (A_s) was measured at 350 nm using hexane with the para-anisidine solution as a blank. The pAV (arbitrary units) was calculated according to eq 2

p A V = \frac{1.2 \times A_{s} - A_{b}}{m}

(2)

where m is the mass (g) of oil per mL of hexane.

2.12. Statistical Analysis

All analyses were carried out in triplicate on at least two independent samples, and data were reported as mean values ± standard deviation. Significance of the results (p < 0.05) was determined by one-way analysis of variance (ANOVA) with Tukey’s post hoc test using IBM SPSS statistics software 23.0.0.2 (SPSS Inc, Chicago, Illinois, USA).

3. Results and Discussion

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3.1. Characterization of Coffee Fractions

3.1.1. Chemical Composition

The carbohydrate, protein, and phenolic contents of different coffee fractions are listed in Table 1. The carbohydrate contents of the coffee brew, HMWF, and LMWF were around 38, 70, and 16 wt %, respectively, which are within the range of values reported in literature. (24,32−35) The majority of the carbohydrates from coffee brew ended up in HMWF (Table 1), indicating that coffee brew carbohydrates are mostly polysaccharides with a minor fraction of simple sugars and oligosaccharides. Mannose, galactose, and arabinose are the most abundant sugar residues in HMWF, which suggests that these are the main constituents of polysaccharides in coffee brew and HMWF. (24,36) During coffee roasting, these polysaccharides undergo structural changes (e.g., depolymerization, debranching, isomerization, and polymerization) and are involved in melanoidin formation. (37,38) The most abundant sugars in LMWF were reported to be mannose and galactose. (39)

Table 1. Composition of Coffee Fractions^a

sample	carbohydrates (wt %)	phenolic compounds (wt %)^b	proteins (wt %)
coffee brew	37.77 ± 0.64^b	20.31 ± 1.02^b	17.30 ± 1.25^ab
HMWF	70.82 ± 3.63^a	16.94 ± 0.76^bc	12.18 ± 1.37^b
non-defatted HMWF	72.85 ± 1.17^a	15.89 ± 1.08^c	10.92 ± 0.12^b
LMWF	16.40 ± 0.50^c	32.30 ± 1.30^a	22.29 ± 4.07^a

^{^a}

Different letters indicate significant differences (P < 0.05) between samples for each component.

^{^b}

CGA was used as a reference phenolic compound.

The protein contents of the coffee brew, HMWF, and LMWF are 17, 12, and 22 wt %, respectively (Table 1), which is in line with other studies. (24,40) Proteins in green coffee beans undergo denaturation, depolymerization, and Maillard reactions during roasting, resulting in compositional and structural changes and integration into the polymeric structure of melanoidins. (41)

Coffee brew, HMWF, and LMWF contain ∼20, 17, and 32 wt % of phenolic compounds, respectively (Table 1), which is in line with the findings of. (24) Potentially, these proportions are overestimated because of interferences with non-polyphenolic materials, in particular proteins, in the Folin–Ciocalteu assay. Therefore, phenolic compounds in their free and bound forms were also analyzed by HPLC-DAD-MS. Free phenolic compounds in coffee brew and LMWF were directly analyzed in aqueous methanol, whereas bound phenolics in HMWF and defatted HMWF were analyzed after alkaline hydrolysis (Table 2). The main phenolic compounds in coffee fractions are CGAs that are derived from esterification of quinic acid and cinnamic acids (including caffeic, ferulic, and p-coumaric acids), including caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs), feruloylquinic acids (FQAs), and p-coumaroylquinic acids (pCoQAs). As shown in Table 2 (detailed data can be found in Table S1), CQAs were present in much higher amounts than FQAs and diCQAs, which is in agreement with Ludwig et al. (42) Free CQAs, FQAs, diCQAs, and caffeoylquinolactones (CQLs) were detected in coffee brew and its LMWF, which is consistent with the findings from previous research. (40) In contrast, no free CGAs were found in HMWFs; during coffee bean roasting, a part of the CGAs is degraded into phenol derivatives keeping their catechol function and bound to melanoidin backbones through covalent linkages (in condensed form and ester linked-form) and, to a lesser extent, via electrostatic interactions, (16,43,44) forming supramolecular assemblies which cannot pass the ultrafiltration membrane. Thus, covalently bound CGAs were measured after the alkaline hydrolysis of HMWFs coffee fractions. For these fractions, the release of caffeic (CA), ferulic (FA), and p-coumaric (pcoum) acids were observed (Table 2), suggesting the incorporation of CQAs, diCQAs, FQAs, caffeoylferuloylquinic acids (CFQAs), and p-coumaroylquinic acids (pCoQAs) into melanoidins. (18)

Table 2. Unbound and Covalently Bound Phenolic Compounds of Coffee Fractions (g/100g).^a

	unbound phenolic compounds		covalently bound phenolic compounds
	coffee brew	LMWF	HMWF	non-defatted HMWF
total CQAs	2.94 ± 0.14	5.50 ± 0.09	nd	nd
total FQAs	0.23 ± 0.02	0.41 ± 0.03	nd	nd
total diCQAs	0.04 ± 0.00	0.07 ± 0.00	nd	nd
total CQLs	0.42 ± 0.03	0.86 ± 0.07	nd	nd
CA	nd	nd	0.44 ± 0.01	0.43 ± 0.02
FA	nd	Nd	0.10 ± 0.00	0.10 ± 0.00
Pcoum	nd	Nd	0.01 ± 0.00	0.01 ± 0.00

^{^a}

nd: not detected; +/– values correspond to standard deviation (n = 3).

Non-defatted HMWF was prepared to investigate how the defatting step would affect the composition of HMWF and the stability of the emulsions prepared with such fractions. As shown in Table 1, the non-defatted HMWF has a similar amount of carbohydrates, phenolic compounds, and proteins compared to the HMWF. Therefore, we expected that if oil was present, this may not affect the physical properties of emulsions but may negatively affect oxidative stability.

3.1.2. Interfacial Activity

The interfacial activity of coffee fractions was determined by their time-dependent capacity to increase the surface pressure at the oil–water interface and was compared with that of WPI, a commonly used emulsifier. As shown in Figure 1, all samples showed a rapid increase in the surface pressure within the first 400 s, followed by a slower increase. However, the surface pressure values obtained with WPI were always higher than those obtained with the coffee fractions. Comparing the coffee fractions, HMWF and non-defatted HMWF led to a higher surface pressure than LMWF, while the surface pressure obtained with coffee brew fell in between those obtained with HMWF and LMWF (Figure 1).

Figure 1. Surface pressure of WPI and coffee fractions (0.01 w/v % in water) as a function of time, at the stripped oil–water interface, at 20 °C. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates.

Whey proteins are known to rapidly diffuse and adsorb at the oil–water interface, thus lowering interfacial tension, and in later stages also re-arranging and forming surface films. (45) HMWF contains amphipathic proteins (e.g., arabinogalactan proteins) as part of the melanoidins and these components are also surface-active. (46) The majority of compounds in the LMWF are highly polar, (40) and this may imply that surface activity is relatively low (Figure 1). The lower surface activity of coffee brew compared to HMWF is a logical combination of the effects found for HMWF and LMWF.

3.2. Coffee Fractions at the Interface of Emulsions

3.2.1. Physical Properties of Emulsions

HMWF from coffee brew (melanoidins) used at concentrations ranging from 0.25 to 4 wt % was previously found to be able to physically stabilize O/W emulsions, among which the 2 wt % melanoidin-stabilized emulsions showed the highest physical stability. (21) Here, we tested all coffee fractions at a concentration of 2 wt % for emulsion preparation, and evaluated their effect on droplet size distribution, microstructure, droplet surface charge, and later also lipid oxidation was monitored throughout storage. WPI (2 wt %)-stabilized emulsions were used as reference emulsions.

With the exception of emulsions stabilized with LMWF that underwent creaming and subsequent oiling off shortly after homogenization, all other freshly prepared emulsions exhibited a nearly monomodal size distribution with a mean droplet size (d_3,2) of ∼0.1 μm (Figure 2). The coffee brew-stabilized emulsions showed a small peak at larger sizes due to slight flocculation and coalescence (Figures 2B and 3). Upon 7 days of storage at 40 °C;, WPI-stabilized emulsions remained fully stable (Figure 2A), whereas multimodal size distributions were observed in emulsions stabilized with coffee brew and HMWF (Figure 2B,C), which was probably caused by flocculation and coalescence of droplets (Figure 3). For the non-defatted HMWF-stabilized emulsions, their droplet size distribution profile remained mostly stable even though a minor tail in the size distribution appeared between 1 and 3 μm (Figure 2D). This does not reflect the observation of large structures in optical microscopy, which look like compact flocs or even oil droplets attached onto solid template structures (Figure 3D2). The reason why such structures were not detected in static light scattering may be because their occurrence was still minor enough not to contribute substantially to the signal measured, or they creamed/sedimented so fast that they were not detected. Nevertheless, no oiling off was detected in all emulsions.

Figure 2. Droplet size distribution of emulsions stabilized with WPI (A), coffee brew (B), HMWF (C), and non-defatted HMWF (D) freshly prepared (solid line) or after 7 days at 40 °C (2) (dotted line). For all emulsions, the concentration of the emulsifying ingredient was 2 wt %. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates.

Figure 3. Microscopic pictures of emulsions stabilized with WPI (A), coffee brew (B), HMWF (C), and non-defatted HMWF (D) freshly prepared (1) or after 7 days at 40 °C (2).

All freshly prepared emulsions had a negative zeta-potential around −40 mV (Figure 4), which was expected because both WPI and coffee melanoidins are negatively charged at pH higher than the isoelectric point (∼5.1 and ∼2.5, respectively). At the end of storage, the emulsions still had a considerable net charge, with significant changes noted (except for coffee brew-stabilized emulsions, Figure 4). The decrease in zeta-potential for WPI-stabilized emulsions might be related to the surface-active fatty acids that may be formed upon lipid hydrolysis, or organic acids generated as a result of lipid oxidation, or degradation of positively charged amino groups. (47−49) In addition, this decrease could also be related to the conformational rearrangements of the whey proteins at the interface, which may lead to an exposure of negatively charged amino groups. The increase in zeta-potential for coffee fraction-stabilized emulsions is most probably the result of a small decrease in pH which reduces the net charge, and this may also favor aggregation of oil droplets (Figures 2 and 3).

Figure 4. Zeta-potential of the emulsions freshly prepared or after 7 days at 40 °C. The lowercase letter is for comparison among different emulsions. Different letters indicate significant differences (P < 0.05). Asterisks indicate a significant difference for the same sample between day 0 and day 7.

3.2.2. Antioxidant Activity of Coffee Fractions

Coffee components may affect oxidative reactions through various mechanisms including scavenging of free radicals and binding of metal ions. Therefore, before analyzing the lipid oxidation in emulsions, the antioxidant properties of coffee fractions were assessed and compared with those of WPI. As can be seen in Figure 5A, WPI exhibited a significantly lower DPPH radical scavenging activity than any of the coffee fractions, among which non-defatted HMWF showed the lowest activity. With respect to the iron-chelating activity, all coffee fractions were able to bind more iron than WPI (Figure 5B), with LMWF having a significantly higher capacity than the other fractions (Figure 5B).

Figure 5. DPPH radical scavenging activity (A) and iron-chelating capacity (B) of WPI and different coffee fractions. The lowercase letter is for comparison among the samples. Different letters indicate significant differences (P < 0.05).

For WPI, it has been suggested that the sulfhydryl groups located on the surface of the molecules have hydrogen-donating ability, (50) whereas the carboxyl groups of acidic amino acids (aspartic acid and glutamic acid) might account for metal-chelating ability. (51) The antioxidant properties of the HMWF are probably due to the melanoidins that contain CGAs. The presence of reductons, enaminol, and hydroxyl groups in phenolic compounds might explain the strong radical scavenging activity, (52) whereas the catechol moieties from incorporated phenolic compounds and the ketone and/or hydroxyl groups of pyranone or pyridone might act as metal chelators. (53,54) LMWF is rich in unbound phenolic compounds, especially those with catechol moieties (e.g., CQAs, Section 3.1) which are effective free radical acceptors and metal chelators. (17,55,56) In addition, the volatile heterocyclic compounds (e.g., pyrrols, furans, and thiophenes) and hydroxybenzenes (e.g., ethylcathecol and pyrogallol) in LMWF may contribute to over antioxidant activity. (18)

3.2.3. Lipid Oxidation in Emulsions

Hydroperoxide concentration (Figure 6A) and para-anisidine value (pAV) (Figure 6B) were used to characterize lipid oxidation in emulsions. WPI-stabilized emulsions showed a rapid initial increase in hydroperoxides, followed by a gradual increase until the end of storage (Figure 6A). Similarly, the pAV of WPI-stabilized emulsions rapidly increased within 1 day of storage, after which it remained constant for the rest of the storage period (Figure 6B). In contrast, the hydroperoxide concentration and pAV of emulsions stabilized by coffee fractions were very low during the accelerated storage at 40 °C (Figure 6A,B; a magnification is therefore shown in Figure 6a,b), indicating that coffee fractions (coffee brew, HMWF, and non-defatted HMWF) were highly effective in preventing oxidation of emulsified lipids.

Figure 6. Hydroperoxide concentrations (left column) and *para*-anisidine values (right column) in different emulsions over the incubation period (40 °C, 7 days). Top row: all emulsions; bottom row: coffee fraction-stabilized emulsions (bottom row graphs show a magnification on low values of oxidation markers; please note the difference in Y-axis scales between panels A/a and panels B/b).

The strong ability of coffee fractions to protect lipids from oxidation can be related to their relatively high antioxidant activity (compared to WPI, Section 3.2.2) and their interfacial localization. In the early stages of incubation, it is likely that trace amounts of pre-existing lipid hydroperoxides (LOOH) located at the oil–water interface would decompose into alkoxy radicals (LO^•) or peroxyl radicals (LOO^•). (57) Some compounds from the adsorbed coffee fractions (e.g., phenolic compounds and melanoidins, as discussed in Section 3.2.2) might act as chain-breaking electron donors, which could readily transfer hydrogen atoms to scavenge LO^• and LOO^•, thereby inhibiting lipid oxidation. (58,59) On the other hand, coffee fractions have metal binding capacity (Figure 5B), which prevents metals from initiating radical formation and decomposing surface-active LOOH. Both relatively high radical scavenging and iron binding capacities seem to be logical explanations for the effectiveness of coffee fractions, whereas the much lower values for WPI are consistent with the greater oxidizability of the corresponding emulsions.

Next to the role of the adsorbed fractions, components present in the continuous phase may also play an important role in lipid oxidation. (20) For example, melanoidins may trap transition metals and free radicals in the continuous phase and thus prevent these aqueous pro-oxidants from getting into contact with labile unsaturated lipids in the droplets. To distinguish between these effects, excess coffee material was added to the continuous phase of preliminary prepared emulsions, and both physical and oxidative stability were monitored.

3.3. Added Coffee Materials to the Continuous Phase of Emulsions

3.3.1. Influence of HMWF Concentrations on the Stability of Emulsions

Stock WPI-stabilized emulsions were prepared with minimal amounts of unadsorbed WPI remaining in the continuous phase, (29) and HMWF suspensions with concentrations ranging from 0 to 2 w/v % were added to the emulsion after homogenization. Physical stability and lipid oxidation were monitored during storage at 40 °C for 4 days.

All emulsions with added HMWF exhibited bimodal size distributions (Figure 7): the peak ranging from 0.01 to 1 μm corresponds to the emulsion droplets, and the second peak to aggregated HMWF in the continuous phase. This is supported by (i) the similar particle size distribution of the HMWF dispersion (Figure 7A, red curve) and (ii) the increased intensity of the second peak as HMWF concentration increased (Figure 7). No appreciable changes in droplet size and microstructure were observed for all emulsions upon storage (Figures 7 and S1), suggesting these emulsions were physically stable.

Figure 7. Droplet size distribution of WPI-stabilized emulsions stabilized with 0 (A), 0.125 (B), 0.25 (C), 0.5 (D), 1 (E), and 2 (F) w/v % HMW coffee melanoidins added to the emulsion post-homogenization. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates. The red curve in (A) is corresponding to the particle size distribution of the HMWF dispersion.

As can be seen in Figure 8, emulsion droplets had a slightly more negative surface charge when the HMWF concentration increased, which may be due to some exchange taking place at the interface, leading to more negatively charged “compounds” from HMWF, such as uronic acids from arabinogalactans and ferulic acid or caffeic acid moieties from CGAs incorporated at the interface. (43) The decrease in zeta-potential over time (Figure 8) can be similarly explained as before by the formation of fatty acids or organic acids, or degradation of the positively charged amino groups, or the conformational rearrangements of the whey proteins (Section 3.2.1).

Figure 8. Zeta-potential of the WPI-stabilized emulsions supplemented with 0–2 w/v % of HMWF freshly prepared or at the end of the incubation period (40 °C, 4 days).

With respect to lipid oxidation, hydroperoxides and aldehydes developed earlier, faster and to a much greater extent in the control emulsion (0 w/v % HMWF) than in the other emulsions (supplemented with 0.125–2 w/v % HMWF) (Figure 9), in which oxidation products were formed according to the amount of HMWF added. It is actually challenging to compare the effects since the difference between the curves is highly time-dependent (as would be expected for cascaded reactions like lipid oxidation). When taking the final concentrations measured, the aldehyde contents were 3.6-, 5.2-, 9.3-, 23-, and 31-fold higher for the control emulsion than emulsions to which HMWF was added at 0.125, 0.25, 0.5, 1, and 2 w/v %, respectively. What is more important to point out is that HMWF was highly efficient even at very low concentrations used in the continuous phase. Most probably, the free radical scavenging and iron-binding abilities (Figure 5A,B) are instrumental in creating such positive effects, as also discussed before. (60)

Figure 9. Hydroperoxide concentrations (A) and *para*-anisidine values (B) in WPI-stabilized emulsions supplemented with 0 to 2 w/v % of HMWF, over the incubation period (40 °C, 4 days).

3.3.2. Influence of Coffee Fractions on the Stability of Emulsions

In the last experiment, the different coffee fractions were added to whey protein-stabilized emulsions, post-homogenization, to test their capacity to inhibit lipid oxidation at a concentration of 0.25 w/v %. Again, no appreciable differences in the physical properties (droplet size distribution, microstructures, and zeta-potentials) were observed during incubation for all emulsions (Figures S2–S4).

With respect to lipid oxidation (Figure 10), the presence of added compounds improved the oxidative stability of emulsions, although WPI was considerably less effective than coffee brew and LMWF, which themselves were less effective than both HMWFs. After 4 days of storage, the aldehyde concentration was 1.0-, 2.0-, 2.2-, 5.2-, and 5.5-fold higher for the control emulsion than for emulsions containing excess WPI, LMWF, coffee brew, HMWF, and non-defatted HMWF, respectively (Figure 10B). The order of appearance is not in line with radical scavenging and iron-chelating activities (Figure 5): although LMWF achieves the best antioxidant activities in single phase test systems, it clearly does not in emulsions. This can be due to the partitioning and physical location of the involved components in emulsions systems, which is why such antioxidant tests are often criticized for their (ir)relevance to model or real food systems.

Figure 10. Hydroperoxide concentrations (A) and *para*-anisidine values (B) in WPI-stabilized emulsions supplemented with excess WPI or various coffee fractions (0.25 wt %) over the incubation period (40 °C, 4 days).

We expect that the positioning of HMWF components at the oil–water interface puts them where their action is needed. Overall, HMWF components may be more likely to bind to the interface than their low-molecular-weight counterparts, (61) as seems to be confirmed by the surface pressure measurements (Figure 1); in addition, assuming they may locate at the interface, adsorbed HMWFs would be less mobile and thus could be more efficient to prevent lipid oxidation by conferring their antioxidant moieties a more substantial residence time at the interface, as compared to low-molecular-weight molecules. (62) Besides, as discussed in Section 3.1.1, unbound phenolic compounds were recovered in LMWF, and covalently bound phenolic compounds were found in HMWF. Unbound phenolic compounds themselves might be oxidized by oxygen and transition metals during the storage at 40 °C, whereas bound phenolic compounds may be protected against oxygen by the large moieties (e.g., melanoidin backbones) they are bound to. (63) In addition, as compared to HMWF, LMWF and coffee brew had higher phenolic contents (Tables 1 and 2), which may result in a higher amount of phenolic compound-bound Fe³⁺ (64) and higher reducing power that reduces Fe³⁺ to Fe²⁺ in emulsions, (49,65) thereby promoting the formation of free radicals and the decomposition of hydroperoxides. Furthermore, the total antioxidant effect of coffee fractions is due to hydrophilic as well as hydrophobic compounds, (66) and thus, depending on the polarity of the media, different compounds might be responsible for the tested antioxidant effect. This implies that antioxidants having a high response in the iron-chelating or DPPH assay may have a low response in the emulsion systems due to partitioning effects. Moreover, obviously, there could still be numerous other components at work, resulting in synergism or antagonism of antioxidants. (67) In spite of this, our finds clearly point to the great potential of coffee fractions to control oxidation in emulsion, either as a main emulsifier, or as an add-on to the emulsion after its preparation.

This work demonstrates the great potential of various coffee fractions in the preparation of emulsions that are physically as well as oxidatively stable. We explored using various fractions as emulsifiers, and as add-ons post emulsification. Especially, the HMWF is able to form emulsions with a nearly monomodal size distribution and keep emulsions chemically stable at 40 °C for 7 days. When added to dairy protein-stabilized emulsions post homogenization, all coffee fractions were able to slow down lipid oxidation considerably without significantly affecting the physical stability of emulsions, though both HMWFs were more effective in retarding lipid oxidation than coffee brew and LMWF.

It is expected that a number of effects, such as the antioxidant properties (metal chelating and radical scavenging activities) of coffee fractions, the partitioning of antioxidant components in the emulsions and the phenolic compounds profile, are responsible for the overall effects that we found. Fractionation into different coffee fractions improves the techno-functional properties of coffee. This research showed that coffee ingredients could act as multifunctional stabilizers with a wide potential for application in dispersed systems (e.g., emulsions) as used in foods, pharmaceutics, and cosmetics. Future work is directed toward understanding the contribution of individual components to the antioxidant activity of coffee fractions.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jafc.2c07365.

Detailed unbound and covalently bound phenolic compounds of coffee fractions; microscopic pictures of WPI-stabilized emulsions with HMWF added to the continuous phase; droplet size distribution of WPI-stabilized emulsions with different fractions added to the continuous phase; microscopic pictures of WPI-stabilized emulsions with different fractions added to the continuous phase; and zeta-potential of WPI-stabilized emulsions with different fractions added to the continuous phase (PDF)

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Author Information

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Corresponding Author
- Claire C. Berton-Carabin - Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands; INRAE, UR BIA, F-44316 Nantes, France; Email: [email protected]
Authors
- Jilu Feng - Food Quality and Design Group, Wageningen University and Research, 6708WG Wageningen, Netherlands; Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands; https://orcid.org/0000-0003-1626-3414
- Karin Schroën - Food Process and Engineering Group, Wageningen University and Research, 6708WG Wageningen, Netherlands
- Sylvain Guyot - INRA UR1268 BIA, F-35653 Le Rheu, France
- Agnès Gacel - INRA UR1268 BIA, F-35653 Le Rheu, France
- Vincenzo Fogliano - Food Quality and Design Group, Wageningen University and Research, 6708WG Wageningen, Netherlands; https://orcid.org/0000-0001-8786-9355
Notes
The authors declare no competing financial interest.

Acknowledgments

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The author Jilu Feng was funded by the Chinese Scholarship Council (CSC).

References

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This article references 67 other publications.

1
Morzelle, M. C.; Watkins, B. A.; Li, Y.; Hennig, B.; Toborek, M. Dietary Lipids and Health. Bailey’s Industrial Oil and Fat Products; John Wiley & Sons, 2020; pp 1– 27.
Google Scholar
There is no corresponding record for this reference.
2
McClements, D. J.; Decker, E. Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation. J. Agric. Food Chem. 2018, 66, 20– 35, DOI: 10.1021/acs.jafc.7b05066
Google Scholar
2
Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation
McClements, David Julian; Decker, Eric
Journal of Agricultural and Food Chemistry (2018), 66 (1), 20-35CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
A review. There has been strong interest in developing effective strategies to inhibit lipid oxidn. in emulsified food products due to the need to incorporate oxidatively labile bioactive lipids, such as w-3 fatty acids, conjugated linoleic acids, or carotenoids. Emulsifiers or co-emulsifiers can be utilized to inhibit lipid oxidn. in emulsions. Both of these mol. types can adsorb to droplet surfaces and inhibit lipid oxidn., but emulsifiers can also stabilize droplets against aggregation whereas co-emulsifiers cannot. There are a host of existing emulsifiers, covalent conjugates, or phys. complexes that have the potential to inhibit lipid oxidn. by a variety of mechanisms. Existing emulsifiers with antioxidant potential consist of surfactants, phospholipids, proteins, polysaccharides and colloidal particles. Conjugates and complexes are typically formed by covalently or phys. linking together a surface-active mol. with an antioxidant mol. This article, reviews the mol. and physicochem. basis for the surface and antioxidant activities of emulsifiers and co-emulsifiers, highlights the important properties of interfacial layers that can be engineered to control lipid oxidn., and outlines different kinds of existing emulsifiers, conjugates, and complexes that can be used to inhibit oxidn.
3
Villière, A.; Rousseau, F.; Brossard, C.; Genot, C. Sensory Evaluation of the Odour of a Sunflower Oil Emulsion throughout Oxidation. Eur. J. Lipid Sci. Technol. 2007, 109, 38– 48, DOI: 10.1002/ejlt.200600084
Google Scholar
3
Sensory evaluation of the odour of a sunflower oil emulsion throughout oxidation
Villiere, Angelique; Rousseau, Florence; Brossard, Chantal; Genot, Claude
European Journal of Lipid Science and Technology (2007), 109 (1), 38-48CODEN: EJLTFM; ISSN:1438-7697. (Wiley-VCH Verlag GmbH & Co. KGaA)
Oxidn. of unsatd. fatty acids is responsible for off-flavours, often described as rancid flavours. This study was aimed at describing the evolution of the odor of a sunflower oil-in-water emulsion during oxidn. at 50 °C in the dark. Appearance of an odor and occurrence of oxidn. were first tested for at short-time aging (0-4 h) by the triangle test and measurements of oxygen consumption, resp. The odor of the emulsion oxidised for up to 240 h was then characterised by sensory profile, while volatiles issued from lipid oxidn. were analyzed in the headspace by SPME. From 1 h of aging, while oxygen consumption remained weak, a significant change of the odor was detected by the panel. Up to 21 volatile compds. were identified in the headspace of long-time-oxidised emulsions. Beyond the rancid attribute, seven attributes were chosen to describe the odor of oxidised emulsions, four of which referring to solns. of a single volatile oxidn. compd. The contribution of the fresh oil attribute, initially dominant, was progressively overtaken from 6 to 24 h of aging by the deep-fried attribute, which later declined in favor of the painty attribute, predominant after 100 h. Evolution of intensity scores and contribution to odor profiles of attributes could not be easily related to one ref. volatile compd. or another, confirming the complex relationship between the generated volatile compds. and the perceived odor.
4
Rasheed, A.; Fathima Abdul Azeez, R. A Review on Natural Antioxidants. In Traditional and Complementary Medicine; IntechOpen, 2019.
Google Scholar
There is no corresponding record for this reference.
5
Parliment, T. H. An Overview of Coffee Roasting. ACS Symp. Ser. 2000, 754, 188– 201, DOI: 10.1021/bk-2000-0754.ch020
Google Scholar
5
An overview of coffee roasting
Parliment, Thomas H.
ACS Symposium Series (2000), 754 (Caffeinated Beverages), 188-201CODEN: ACSMC8; ISSN:0097-6156. (American Chemical Society)
A review with 25 refs. The coffee beverage as presently consumed is an aq. ext. of the roasted and ground seed of the fruit of the coffee plant. It is consumed for its pleasant flavor and aroma and its stimulatory properties due to caffeine. The flavor of roasted coffee is quite complex; chem. and flavor changes occur when the bean is roasted and nearly 800 aroma compds. are generated.
6
Panusa, A.; Zuorro, A.; Lavecchia, R.; Marrosu, G.; Petrucci, R. Recovery of Natural Antioxidants from Spent Coffee Grounds. J. Agric. Food Chem. 2013, 61, 4162– 4168, DOI: 10.1021/jf4005719
Google Scholar
6
Recovery of natural antioxidants from spent coffee grounds
Panusa, Alessia; Zuorro, Antonio; Lavecchia, Roberto; Marrosu, Giancarlo; Petrucci, Rita
Journal of Agricultural and Food Chemistry (2013), 61 (17), 4162-4168CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Spent coffee grounds (SCG) were extd. with an environmentally friendly procedure and analyzed to evaluate the recovery of relevant natural antioxidants for use as nutritional supplements, foods, or cosmetic additives. SCG were characterized in terms of their total phenolic content by the Folin-Ciocalteu procedure and antioxidant activity by the DPPH scavenging assay. Flavonoid content was also detd. by a colorimetric assay. The total phenolic content was strongly correlated with the DPPH scavenging activity, suggesting that phenolic compds. are mainly responsible for the antioxidant activity of SCG. An UHPLC-PDA-TOF-MS system was used to sep., identify, and quantify phenolic and nonphenolic compds. in the SCG exts. Important amts. of chlorogenic acids (CGA) and related compds. as well as caffeine (CAF) evidenced the high potential of SCG, a waste material that is widely available in the world, as a source of natural phenolic antioxidants.
7
Del Pino-García, R.; González-SanJosé, M. L.; Rivero-Pérez, M. D.; Muñiz, P. Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee: Contribution of the Melanoidin Fraction. J. Agric. Food Chem. 2012, 60, 10530– 10539, DOI: 10.1021/jf302747v
Google Scholar
7
Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee: Contribution of the Melanoidin Fraction
Del Pino-Garcia, Raquel; Gonzalez-SanJose, Maria L.; Rivero-Perez, Maria D.; Muniz, Pilar
Journal of Agricultural and Food Chemistry (2012), 60 (42), 10530-10539CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The roasting process induces chem. changes in coffee beans that strongly affect the antioxidant activity of coffee. The polyphenol and melanoidin contents and the antioxidant activity of three instant coffees with different roasting degrees (light, medium, and dark) were assessed. Coffee brews were sepd. into fractions, and the potential biol. activity of the melanoidins was evaluated by simulating their gastrointestinal digestion. Total antioxidant capacity, hydroxyl radical scavenger activity, lipid peroxidn. inhibition capacity, and protection against DNA oxidative damage (in vitro and ex vivo genoprotective effects) were detd. Instant coffee has a high total antioxidant capacity and protective effect against certain oxidative stress biomarkers (lipids and DNA), although this capacity decreases with the roasting degree. This confirms the hypothesis that several of the polyphenols present in coffee may become part of the melanoidins generated during roasting. Furthermore, the elevated genoprotective effect of melanoidin-digested fractions is noteworthy.
8
Delgado-Andrade, C.; Morales, F. J. Unraveling the Contribution of Melanoidins to the Antioxidant Activity of Coffee Brews. J. Agric. Food Chem. 2005, 53, 1403– 1407, DOI: 10.1021/jf048500p
Google Scholar
8
Unraveling the contribution of melanoidins to the antioxidant activity of coffee brews
Delgado-Andrade, Cristina; Morales, Francisco J.
Journal of Agricultural and Food Chemistry (2005), 53 (5), 1403-1407CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Instant coffees produced from the same green coffee beans were supplied from a company in different roasting degrees, light, medium, and dark. Melanoidins were obtained by ultrafiltration (10 kDa) and subsequent diafiltration. Pure melanoidins were isolated from melanoidins after overnight incubation in 2 M NaCl. The antioxidant activities of instant coffees, melanoidins, and pure melanoidins were tested using the conjugated diene formation from a 2,2'-azobis(2-amidinopropane) dihydrochloride-induced linoleic acid oxidn. in an aq. system. No significant differences were found between melanoidins and pure melanoidins with different roasting degrees. Therefore, the contribution of the pure melanoidin fraction to the total antioxidant activity of melanoidins was significantly lower. More than 50% of the antioxidant activity of melanoidins is due to low mol. wt. compds. linked non-covalently to the melanoidin skeleton. A new concept of the overall antioxidant properties of food melanoidins is described, where chelating ability toward low mol. wt. antioxidant compds. is connected to the stabilization of these compds. involved in the shelf life of the product.
9
ALjahdali, N.; Carbonero, F. Impact of Maillard Reaction Products on Nutrition and Health : Current Knowledge and Need to Understand Their Fate in the Human Digestive System. Crit. Rev. Food Sci. Nutr. 2019, 59, 474– 487, DOI: 10.1080/10408398.2017.1378865
Google Scholar
9
Impact of Maillard reaction products on nutrition and health: Current knowledge and need to understand their fate in the human digestive system
Aljahdali, Nesreen; Carbonero, Franck
Critical Reviews in Food Science and Nutrition (2019), 59 (3), 474-487CODEN: CRFND6; ISSN:1040-8398. (Taylor & Francis, Inc.)
The Maillard Reaction (MR) is a non-enzymic chem. reaction which results in the linkage between the amino group of amino acids and the carbonyl group of reduced sugars. MR products (MRPs) are common components of processed foods, mainly as a result of heating, esp. in the Western diet. MRPs are classified as into three stages: initial, intermediate, and final stages, indicative of increased complexity and size, incurring different flavor, aroma, and texture. MRPs presence is known to reduce the nutritional quality of foods, particularly by reducing protein digestibility. Early reports have linked MRPs, esp. advanced glycation end-products (AGEs) present in high concn. in the typical Western diet, to health conditions and diseases. However conflicting data has since been reported, and only a few (acrylamide, heterocyclic amines and 5-Hydroxymethylfurfural) MRPs have documented potential toxic or carcinogenic effects. High mol. wt. MRPs are not available for direct absorption in the higher gastrointestinal tract, and are thus mostly metabolized by resident colonic microbes. MRPs have been the subject of sparse research interest in comparison with other non-digestible dietary elements. In this review, we outline the state of knowledge on MRPs in nutrition and health, and highlight the need to develop the limited knowledge on their impact on the gut microbiota and which metabolites derive from MRPs fermn.
10
Delgado-andrade, C.; Fogliano, V. Dietary Advanced Glycosylation End-Products (DAGEs) and Melanoidins Formed through the Maillard Reaction: Physiological Consequences of Their Intake. Annu. Rev. Food Sci. Technol. 2018, 9, 271, DOI: 10.1146/annurev-food-030117-012441
Google Scholar
10
Dietary Advanced Glycosylation End-Products (dAGEs) and Melanoidins Formed through the Maillard Reaction: Physiological Consequences of their Intake
Delgado-Andrade, Cristina; Fogliano, Vincenzo
Annual Review of Food Science and Technology (2018), 9 (), 271-291CODEN: ARFSBV; ISSN:1941-1413. (Annual Reviews)
The main purpose of this review is to clarify whether the consumption of food rich in melanoidins and dietary advanced glycosylation end-products (dAGEs) is harmful or beneficial for human health. There are conflicting results on their harmful effects in the literature, partly due to a methodol. issue in how dAGEs are detd. in food. Melanoidins have pos. functions particularly within the gastrointestinal tract, whereas the intake of dAGEs has controversial physiol. consequences. Most of the in vivo intervention trials were done comparing boiled vs. roasted diet (low and high dAGE, resp.). However, these studies can be biased by different lipid oxidn. and by different calorie d. of foods in the two conditions. The attraction that humans have to cooked foods is linked to the benefits they have had during mankind's evolution. The goal for food technologists is to design low-energy-dense products that can satisfy humans' attraction to rewarding cooked foods.
11
Yanagimoto, K.; Ochi, H.; Lee, K. G.; Shibamoto, T. Antioxidative Activities of Fractions Obtained from Brewed Coffee. J. Agric. Food Chem. 2004, 52, 592– 596, DOI: 10.1021/jf030317t
Google Scholar
11
Antioxidative Activities of Fractions Obtained from Brewed Coffee
Yanagimoto, Kenichi; Ochi, Hirotomo; Lee, Kwang-Geun; Shibamoto, Takayuki
Journal of Agricultural and Food Chemistry (2004), 52 (3), 592-596CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The antioxidative activity of column chromatog. fractions obtained from brewed coffee was investigated to find antioxidants and to assess the benefit of coffee drinking. The dichloromethane ext. inhibited hexanal oxidn. by 100 and 50% for 15 days and 30 days, resp., at the level of 5 μg/mL. A GC/MS anal. of fractions, which exhibited oxidative activity, revealed the presence of antioxidative heterocyclic compds. including furans, pyrroles, and maltol. The residual aq. soln. exhibited slight antioxidative activity. The inhibitory activity of the 7 fractions from an aq. soln. toward malonaldehyde formation from lipid oxidn. ranged from 10 to 90 at a level of 300 μg/mL. Thus, brewed coffee contains many antioxidants and consumption of antioxidant-rich brewed coffee may inhibit diseases caused by oxidative damages.
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Delgado-Andrade, C.; Rufián-Henares, J. A.; Morales, F. J. Assessing the Antioxidant Activity of Melanoidins from Coffee Brews by Different Antioxidant Methods. J. Agric. Food Chem. 2005, 53, 7832– 7836, DOI: 10.1021/jf0512353
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Assessing the Antioxidant Activity of Melanoidins from Coffee Brews by Different Antioxidant Methods
Delgado-Andrade, Cristina; Rufian-Henares, Jose A.; Morales, Francisco J.
Journal of Agricultural and Food Chemistry (2005), 53 (20), 7832-7836CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Antioxidant activity of instant coffees produced from the same green coffee beans roasted at three different degrees was analyzed. Coffee melanoidins were obtained by ultrafiltration (10 kDa cutoff) and subsequent diafiltration. Pure melanoidins were isolated from melanoidins after overnight incubation in 2 M NaCl and then ultrafiltered. Filtrates, corresponding to the low mol. wt. (LMW) fraction noncovalently linked to the melanoidin skeleton, were also preserved. Antioxidant activity of coffee brews (CB), melanoidins (M), pure melanoidins (PM), and bound melanoidin compds. (BMC) were tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing power (FRAP) methods. The higher contribution of melanoidins to the total antioxidant activity of coffees was shown to be caused by the LMW compds. linked noncovalently to the melanoidin skeleton, as data from BMC confirmed. CB, M, and BMC fractions exert the highest antioxidant activity in aq. media, whereas PM was not dependent on the reaction media. The highest correlation was found between DPPH and FRAP methods.
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Mesías, M.; Delgado-Andrade, C. Melanoidins as a Potential Functional Food Ingredient. Curr. Opin. Food Sci. 2017, 14, 37– 42, DOI: 10.1016/j.cofs.2017.01.007
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There is no corresponding record for this reference.
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Echavarría, A. P.; Pagán, J.; Ibarz, A. Melanoidins Formed by Maillard Reaction in Food and Their Biological Activity. Food Eng. Rev. 2012, 4, 203– 223, DOI: 10.1007/s12393-012-9057-9
Google Scholar
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Melanoidins formed by Maillard reaction in food and their biological activity
Echavarria, A. P.; Pagan, J.; Ibarz, A.
Food Engineering Reviews (2012), 4 (4), 203-223CODEN: FEROB9; ISSN:1866-7910. (Springer)
This paper is a review of the recent studies on Maillard reaction products, the formation mechanism for these compds. and melanoidin structure, the undesirable consequences in food esp. in fruit juice processing, the desirable effects and the biol. properties related to health benefits. Melanoidins are compds. generated in the late stages of the Maillard reaction from reducing sugars and proteins or amino acids during food processing and preservation. Recently, the effects of melanoidins on human health and the chem. characterization of the beneficial components have gained a lot of attention, and their implications on several levels, sensory, nutritional, toxicol. and technol. were investigated. Food melanoidins have been reported to be anionic, colored compds., and some of their key chromophores have been elucidated. The antioxidant activity and other biol. effects of melanoidins from real foods and model systems have been widely studied. Despite this, very few different melanoidin structures have actually been described, and specific health effects have yet to be linked with chem. distinct melanoidins. The variety of Maillard reaction products formed during the reaction, in conjunction with the difficulty in purifying and identifying them, makes a thorough anal. of melanoidins challenging.
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Moreira, A. S. P.; Nunes, F. M.; Domingues, M. R.; Coimbra, M. A. Coffee Melanoidins: Structures, Mechanisms of Formation and Potential Health Impacts. Food Funct. 2012, 3, 903– 915, DOI: 10.1039/c2fo30048f
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Coffee melanoidins: structures, mechanisms of formation and potential health impacts
Moreira, Ana S. P.; Nunes, Fernando M.; Domingues, M. Rosario; Coimbra, Manuel A.
Food & Function (2012), 3 (9), 903-915CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
A review. During the roasting process, coffee bean components undergo structural changes leading to the formation of melanoidins, which are defined as high mol. wt. nitrogenous and brown-colored compds. As coffee brew is one of the main sources of melanoidins in the human diet, their health implications are of great interest. In fact, several biol. activities, such as antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative activities, have been attributed to coffee melanoidins. To understand the potential of coffee melanoidin health benefits, it is essential to know their chem. structures. The studies undertaken to date dealing with the structural characterization of coffee melanoidins have shown that polysaccharides, proteins, and chlorogenic acids are involved in coffee melanoidin formation. However, exact structures of coffee melanoidins and mechanisms involved in their formation are far from being elucidated. This paper systematizes the available information and provides a crit. overview of the knowledge obtained so far about the structure of coffee melanoidins, mechanisms of their formation, and their potential health implications.
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Coelho, C.; Ribeiro, M.; Cruz, A. C. S.; Domingues, M. R. M.; Coimbra, M. A.; Bunzel, M.; Nunes, F. M. Nature of Phenolic Compounds in Coffee Melanoidins. J. Agric. Food Chem. 2014, 62, 7843– 7853, DOI: 10.1021/jf501510d
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Nature of Phenolic Compounds in Coffee Melanoidins
Coelho, Carina; Ribeiro, Miguel; Cruz, Ana C. S.; Domingues, M. Rosario M.; Coimbra, Manuel A.; Bunzel, Mirko; Nunes, Fernando M.
Journal of Agricultural and Food Chemistry (2014), 62 (31), 7843-7853CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Phenolic compds. are incorporated into coffee melanoidins during roasting mainly in condensed form (42-62 mmol/100 g) and also in ester-linked form (1.1-1.6 mmol/100 g), with incorporation levels depending on the green coffee chlorogenic acid content. The phenolic compds. are incorporated in different coffee melanoidin populations, but mainly in those sol. in 75% ethanol (82%), a significant correlation between the amt. of phenolic compds. and the amt. of protein and color characteristics of the different melanoidin populations being obsd. The incorporation of phenolic compds. into coffee melanoidins is a significant pathway of chlorogenic acid degrdn. during roasting, representing 23% of the chlorogenic acids lost. These account for the nearly 26% of the material not accounted for by polysaccharides and proteins present in coffee melanodins. The cleavage mechanism and the efficiency of alk. fusion used to release condensed phenolics from coffee melanoidins suggest that the phenolic compds. can be linked to the polymeric material by aryl-ether, stilbene type, and/or biphenyl linkages.
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Verzelloni, E.; Tagliazucchi, D.; Del Rio, D.; Calani, L.; Conte, A. Antiglycative and Antioxidative Properties of Coffee Fractions. Food Chem. 2011, 124, 1430– 1435, DOI: 10.1016/j.foodchem.2010.07.103
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There is no corresponding record for this reference.
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Perrone, D.; Farah, A.; Donangelo, C. M. Influence of Coffee Roasting on the Incorporation of Phenolic Compounds into Melanoidins and Their Relationship with Antioxidant Activity of the Brew. J. Agric. Food Chem. 2012, 60, 4265– 4275, DOI: 10.1021/jf205388x
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Influence of Coffee Roasting on the Incorporation of Phenolic Compounds into Melanoidins and Their Relationship with Antioxidant Activity of the Brew
Perrone, Daniel; Farah, Adriana; Donangelo, Carmen M.
Journal of Agricultural and Food Chemistry (2012), 60 (17), 4265-4275CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
In the present study, the influence of coffee roasting on free and melanoidin-bound phenolic compds. and their relationship with the brews' antioxidant activity (AA), evaluated by TRAP, TEAC, and TRAP, were investigated. Changes in the relative content of free chlorogenic acids (CGA), free lactones, and melanoidin-bound phenolic acids during roasting indicate that phenolic compds. were incorporated into melanoidins mainly at early stages of the process, being thereafter partly oxidized to dihydrocaffeic acid, and degraded. Although less than 1% of CGA in green coffee was incorporated into melanoidins during roasting, the relative content of melanoidin-bound phenolic acids increased significantly during this process, reaching up to 29% of total phenolic compds. in brews from dark roasted coffees. Regardless of the AA assay used and considering all roasting degrees, the overall contribution of CGA to the AA of the whole brews was higher than that of melanoidin-bound phenolic compds. It was estd. that the latter compds. contributed to 25-47% of the AA, depending on the assay used.
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Decker, E. A.; McClements, D. J.; Bourlieu-Lacanal, C.; Durand, E.; Figueroa-Espinoza, M. C.; Lecomte, J.; Villeneuve, P. Hurdles in Predicting Antioxidant Efficacy in Oil-in-Water Emulsions. Trends Food Sci. Technol. 2017, 67, 183– 194, DOI: 10.1016/j.tifs.2017.07.001
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Hurdles in Predicting Antioxidant Efficacy in Oil-in-water emulsions
Decker, Eric A.; McClements, D. Julian; Bourlieu-Lacanal, Claire; Durand, Erwann; Figueroa-Espinoza, Maria Cruz; Lecomte, Jerome; Villeneuve, Pierre
Trends in Food Science & Technology (2017), 67 (), 183-194CODEN: TFTEEH; ISSN:0924-2244. (Elsevier Ltd.)
A review. Numerous compds. exist in nature that can scavenge free radicals and thus have the potential to act as antioxidants in foods. Interest in natural free radical scavengers has resulted in tens of thousands of publications on various mols. and exts. but only an extremely small no. have actually been used in com. applications. The gap between research interest and com. application is mainly due to the lack of bench top methods that can predict the efficacy of antioxidants in complex food matrixes. This disconnection seems to be due to the extremely complex nature of lipid oxidn. and antioxidant activity in even relatively simple food systems such as oil-in-water emulsions. This review highlights a no. of areas where lack of knowledge is currently holding back our ability to predict which free radical scavengers will be good antioxidants in emulsions: non-free radical scavenging reactions of antioxidants; the existence of different types of oil-water interfaces; difficulties in characterizing lipid droplet surfaces; and differences in oxidn. kinetics in different lipid droplets. Further research is needed to identify the key factors that det. antioxidant efficacy in complex heterogeneous systems. This knowledge would then increase our ability to predict how antioxidant structure and properties relate to their activity in food emulsions.
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Berton-Carabin, C. C.; Ropers, M. H.; Genot, C. Lipid Oxidation in Oil-in-Water Emulsions: Involvement of the Interfacial Layer. Compr. Rev. Food Sci. Food Saf. 2014, 13, 945– 977, DOI: 10.1111/1541-4337.12097
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Lipid oxidation in oil-in-water emulsions: involvement of the interfacial layer
Berton-Carabin, Claire C.; Ropers, Marie-Helene; Genot, Claude
Comprehensive Reviews in Food Science and Food Safety (2014), 13 (5), 945-977CODEN: CRFSBJ; ISSN:1541-4337. (Institute of Food Technologists)
A review. More polyunsatd. fats in processed foods and fewer additives are a huge demand of public health agencies and consumers. Consequently, although foods have an enhanced tendency to oxidize, the usage of antioxidants, esp. synthetic antioxidants, is restrained. An alternate soln. is to better control the localization of reactants inside the food matrix to limit oxidn. This review establishes the state-of-the-art on lipid oxidn. in oil-in-water (O/W) emulsions, with an emphasis on the role of the interfacial region, a crit. area in the system in that respect. We first provide a summary on the essential basic knowledge regarding (i) the structure of O/W emulsions and interfaces and (ii) the general mechanisms of lipid oxidn. Then, we discuss the factors involved in the development of lipid oxidn. in O/W emulsions with a special focus on the role played by the interfacial region. The multiple effects that can be attributed to emulsifiers according to their chem. structure and their location, and the interrelationships between the parameters that define the physicochem. and structure of emulsions are highlighted. This work sheds new light on the interpretation of reported results that are sometimes ambiguous or contradictory.
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Feng, J.; Berton-Carabin, C. C.; Guyot, S.; Gacel, A.; Fogliano, V.; Schroën, K. Coffee Melanoidins as Emulsion Stabilizers. Food Hydrocolloids 2023, 139, 108522, DOI: 10.1016/j.foodhyd.2023.108522
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Coffee melanoidins as emulsion stabilizers
Feng, Jilu; Berton-Carabin, Claire C.; Guyot, Sylvain; Gacel, Agnes; Fogliano, Vincenzo; Schroen, Karin
Food Hydrocolloids (2023), 139 (), 108522CODEN: FOHYES; ISSN:0268-005X. (Elsevier Ltd.)
The use of conventional food stabilizers (e.g., surfactants and animal-derived proteins) is not in line with consumer demands for natural products. This has led to a great interest in novel emulsion stabilizers. In this paper, we explore the emulsification properties of coffee melanoidins, which are brown polymers made up by polysaccharides, proteins and polyphenols formed during bean roasting. The phys. properties and stability of oil-in-water (O/W) emulsions (10 wt% oil) stabilized with 0.25-4 wt% coffee melanoidins were investigated upon storage. Coffee melanoidins can form emulsions with a nearly monomodal size distribution. Upon 28 days of storage at room temp., emulsions prepd. with low (0.25-1 wt%) melanoidin concns. underwent creaming, flocculation, and coalescence; emulsions prepd. with high (4 wt%) melanoidin concns. gradually transformed from a liq.-like state to a gel-like structure, and emulsions prepd. with 2 wt% melanoidins were phys. stable. Stabilization of the emulsions is explained by both interfacial effects and an increased viscosity at high melanoidin concns. Surface load detn., confocal laser scanning microscopy (CLSM), and polarized light microscopy revealed that polysaccharide-rich melanoidins were able to adsorb at the droplet surface. We conclude that coffee melanoidins act both as emulsifiers (decreasing the interfacial tension and inducing electrostatic and steric repulsion) and texture modifiers (increasing the viscosity of emulsions). Coffee melanoidins can be used as natural emulsifiers in targeted food products.
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Berton, C.; Genot, C.; Ropers, M. Quantification of Unadsorbed Protein and Surfactant Emulsifiers in Oil-in-Water Emulsions. J. Colloid Interface Sci. 2011, 354, 739– 748, DOI: 10.1016/j.jcis.2010.11.055
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Quantification of unadsorbed protein and surfactant emulsifiers in oil-in-water emulsions
Berton, Claire; Genot, Claude; Ropers, Marie-Helene
Journal of Colloid and Interface Science (2011), 354 (2), 739-748CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
Unadsorbed emulsifiers affect the phys. and chem. behavior of oil-in-water (O/W) emulsions. A simple methodol. to quantify unadsorbed emulsifiers in the aq. phase of O/W emulsions was developed. Emulsions were centrifuged and filtered to sep. the aq. phase from the oil droplets and the concn. of unadsorbed emulsifiers in the aq. phase detd. The quantification of unadsorbed surfactants based on the direct transesterification of their fatty acids was validated for Tween 20, Tween 80, citric acid ester (Citrem), Span 20 and monolauroyl glycerol. To det. unadsorbed proteins, results obtained with Folin-Ciocalteu reagent or UV-spectrophotometry were compared on emulsions stabilized by β-lactoglobulin (BLG), β-casein (BCN) or bovine serum albumin (BSA). The 1st method gave more accurate results esp. during aging of emulsions in oxidative conditions. The whole methodol. was applied to emulsions stabilized with single or mixed emulsifiers. This approach enables optimization of emulsion formulations and could be useful to follow changes in the levels of unadsorbed emulsifiers during phys. or chem. aging processes.
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Nielsen, S. S. Phenol-Sulfuric Acid Method for Total Carbohydrates. In Food Analysis Laboratory Manual; Nielsen, S. S., Ed.; Springer US: Boston, MA, 2010, pp 47– 53.
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There is no corresponding record for this reference.
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Bekedam, E. K.; Schols, H. A.; van Boekel, M. A. J. S.; Smit, G. High Molecular Weight Melanoidins from Coffee Brew. J. Agric. Food Chem. 2006, 54, 7658– 7666, DOI: 10.1021/jf0615449
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High Molecular Weight Melanoidins from Coffee Brew
Bekedam, E. Koen; Schols, Henk A.; van Boekel, Martinus A. J. S.; Smit, Gerrit
Journal of Agricultural and Food Chemistry (2006), 54 (20), 7658-7666CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The compn. of high mol. wt. (HMw) coffee melanoidin populations, obtained after ethanol pptn., was studied. The specific extinction coeff. (Kmix) at 280, 325, 405 nm, sugar compn., phenolic group content, nitrogen content, amino acid compn., and non-protein nitrogen (NPN) content were investigated. Results show that most HMw coffee melanoidins are sol. at high ethanol concns. The amino acid compn. of the HMw fractions was similar, while 17% (wt./wt.) of the nitrogen was NPN, probably originating from degraded amino acids/proteins and now part of melanoidins. A strong correlation between the melanoidin content, the NPN, and protein content was found. It was concluded that proteins are incorporated into the melanoidins and that the degree of chem. modification, for example, by phenolic groups, dets. the soly. of melanoidins in ethanol. Although the existence of covalent interaction between melanoidins and polysaccharides were not proven in this study, the findings suggest that esp. arabinogalactan is likely involved in melanoidin formation. Finally, phenolic groups were present in the HMw fraction of coffee, and a correlation was found with the melanoidin concn.
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Singleton, V. L.; Rossi, J. A. Colorimetry of Total Phenolics With Phosphomolybdic-Phosphotungstic Acid Reagents. Am. J. Enol. Vitic. 1965, 16, 144– 158
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Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid reagents
Singleton, V. L.; Rossi, Joseph A., Jr.
American Journal of Enology and Viticulture (1965), 16 (3), 144-58CODEN: AJEVAC; ISSN:0002-9254.
The spectral properties, typical molar absorptivities with known compds., and various procedural variables of importance in detg. phenolic substances in natural products by means of Folin-Denis type reagents were investigated. The Folin-Ciocalteu form of the reagent is preferred over the Folin-Denis form previously recommended for "tannin" detn. in wines and spirits. Anhyd. gallic acid is recommended as the reference standard instead of tannic acid. Time, temp., and alkali concn. to give max. color development and avoid appreciable fading were studied. Numerically comparable results, a least equiv. accuracy, and considerably improved reproducibility were shown if the procedure was modified to the following form. Samples (1.00 ml. of white wine or a 1/10 diln. of red wine) are mixed with at least 60 ml. of distd. H2O in a 100-ml. volumetric flask. Five ml. Folin-Ciocalteu reagent is added and mixed, and after about 30 sec. and before 8 min. 3.0 g. of anhyd. Na2CO3 in aq. soln. (e.g. 15 ml. of 200 g./l.) is added, mixed, and the contents of the flask dild. to vol. After 2 hrs. at 75°F. the absorbance at 765 mμ is detd. in comparison with a similarly prepd. set of gallic acid standards of about 0-500 γ/flask. A procedure scaled down to a final vol. of 20.00 ml. is also given.
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Zhang, H.; Zhang, H.; Troise, A. D.; Fogliano, V. Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions. J. Agric. Food Chem. 2019, 67, 10921– 10929, DOI: 10.1021/acs.jafc.9b03744
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Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions
Zhang, Hao; Zhang, Hui; Troise, Antonio Dario; Fogliano, Vincenzo
Journal of Agricultural and Food Chemistry (2019), 67 (39), 10921-10929CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Free amino residues react with α-dicarbonyl compds. (DCs) contributing to the formation of advanced glycation end-products (AGEs). Phenolic compds. can scavenge DCs thus controlling dietary carbonyl load. This study showed that high mol. wt. cocoa (HMW-COM), bread (HMW-BM) and esp. coffee (HMW-CM) melanoidins are effective DCs scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiol. conditions, suggesting some physiol. relevance. Partial acid hydrolysis of HMW-CM decreased dicarbonyl trapping capacity demonstrating that the ability to react with glyoxal, methylglyoxal and diacetyl was mainly due to polyphenols bound to macromols. Caffeic acid and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and arom. substitution reactions led to the formation of a stable adduct between caffeic acid and methylglyoxal. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGEs formation across the gastrointestinal tract.
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Yen, G.-C.; Hsieh, P.-P. Antioxidative Activity and Scavenging Effects on Active Oxygen of Xylose-lysine Maillard Reaction Products. J. Sci. Food Agric. 1995, 67, 415– 420, DOI: 10.1002/jsfa.2740670320
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Antioxidative activity and scavenging effects on active oxygen of xylose-lysine maillard reaction products
Yen, Gow-Chin; Hsieh, Ping-Ping
Journal of the Science of Food and Agriculture (1995), 67 (3), 415-20CODEN: JSFAAE; ISSN:0022-5142. (Wiley)
The antioxidative activity and scavenging effects on active oxygen of Maillard reaction products (MRP) prepd. by heating xylose and lysine (XL) at a molar ratio 1:2 and pH 9.0 for 1-5 h (XL-1 to XL-5) were investigated. The antioxidative activity and browning intensity of XL MRP increased with increasing duration of reaction, but XL-1 and XL-2 MRP showed greater reducing power than other samples. All XL MRP showed scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. XL-1, XL-2 and XL-3 MRP exhibited about 50% redn. in absorbance of superoxide. Scavenging effects of XL MRP on DPPH radical and superoxide were markedly decreased after decolorization with Sep-Pak Cartridge C18, indicating that the browning pigment might contain components that can scavenge superoxide or donate hydrogen atoms. The ESR spectra indicated that XL MRP had scavenging activity on the hydroxyl radical; this scavenging effect depended on dose (r = 0.99) and increased with increasing duration of reaction. Based on these data, the antioxidative activity of XL MRP may be attributed to the combined effects of reducing power, donation of hydrogen atoms and scavenging of active oxygen.
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Hennessy, D. J.; Reid, G. R.; Smith, F. E.; Thompson, S. L. Ferene ─ a New Spectrophotometric Reagent for Iron. Can. J. Chem. 1984, 62, 721– 724, DOI: 10.1139/v84-121
Google Scholar
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Ferene - a new spectrophotometric reagent for iron
Hennessy, Douglas J.; Reid, Gary R.; Smith, Frank E.; Thompson, Stephen L.
Canadian Journal of Chemistry (1984), 62 (4), 721-4CODEN: CJCHAG; ISSN:0008-4042.
A ferene iron reagent, 3-(2-pyridyl)-5,6-bis(2-(5-furyl sulfonic acid)-1,2,4-triazine, disodium salt, monohydrate, was synthesized and characterized. Results of a study of its complex formation with Fe(II) including λmax, εmax, and log K values are reported. The title reagent is suggested for serum Fe detn. as a substitute for Ferrozine.
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Feng, J.; Schroën, K.; Fogliano, V.; Berton-Carabin, C. Antioxidant Potential of Non-Modified and Glycated Soy Proteins in the Continuous Phase of Oil-in-Water Emulsions. Food Hydrocolloids 2021, 114, 106564, DOI: 10.1016/j.foodhyd.2020.106564
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Antioxidant potential of non-modified and glycated soy proteins in the continuous phase of oil-in-water emulsions
Feng, Jilu; Schroen, Karin; Fogliano, Vincenzo; Berton-Carabin, Claire
Food Hydrocolloids (2021), 114 (), 106564CODEN: FOHYES; ISSN:0268-005X. (Elsevier Ltd.)
Food emulsions with a high omega-3 polyunsatd. fatty acid content are desirable from a nutritional point of view. However, such products are particularly prone to lipid oxidn. and have thus a limited shelf-life. The use of natural antioxidants is a promising and consumer-oriented strategy to counteract lipid oxidn. The addn. of an excess of proteins to the continuous phase may be considered in that respect. Starting emulsions were prepd. with either Tween 20 (a nonionic surfactant) or whey protein isolate (WPI). They were then supplemented with non-modified or dextran-glycated soy protein isolate (SPI) added to the continuous phase. As controls, emulsions with excess WPI or unreacted SPI/dextran mixt. were also prepd. The addn. of these compds. did not significantly affect the phys. stability of emulsions, while the lipid oxidn. inhibition capacity was, starting from the highest, in the order glycated SPI mixt. > SPI/dextran mixt. > SPI > WPI. This suggests that SPI ingredients and dextran hold potential for mitigating lipid oxidn. in emulsions. The antioxidant mechanisms involved include iron-binding and free radical-scavenging activities; the former effect is predominant by preventing transition metals from approaching the oil-water interface. Furthermore, compared to WPI-stabilized emulsions, the antioxidant potential of excess proteins is boosted in Tween 20-stabilized emulsions. Interaction of surfactants with proteins could lead to a conformational change of proteins, which could increase their ability to bind mols. involved in the reaction cascade. This study shows that it is possible to tune emulsions towards greater oxidative stability by adjusting protein localization and continuous phase compn., which reduces the need for synthetic antioxidants.
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Shantha, N. C.; Decker, E. A. Iron-Based Spectrophotometric Methods for Determination of Peroxide Values of Food Lipids. J. AOAC Int. 1994, 77, 421– 424, DOI: 10.1093/jaoac/77.2.421
Google Scholar
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Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids
Shantha, Malur C.; Decker, Eric A.
Journal of AOAC International (1994), 77 (2), 421-4CODEN: JAINEE; ISSN:1060-3271.
The official International Dairy Federation method for detn. of the peroxide value of anhyd. milk fat was extended to poultry, meat, fish, and vegetable oils. The ferrous oxidn.-xylenol orange method for detn. of peroxide values of liposomes and lipoproteins was modified to make it simpler and more rapid. These 2 spectrophotometric methods were used successfully to det. the peroxide values of beef, chicken, butter, fish, and vegetable products. The results in most cases were consistent with those obtained by using the AOAC Official Method. The spectrophotometric methods have an assay time of less than 10 min, require ≤0.3 g fat, and are capable of detg. peroxide values as low as 0.1 mequiv/kg of sample.
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AOCS. P-Anisidine Value─Official Method CD 18-90. Official Methods and Recommended Practices of the American Oil Chemists; AOCS Press: Champaign (USA), 1998.
Google Scholar
There is no corresponding record for this reference.
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Bekedam, E. K.; Loots, M. J.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Roasting Effects on Formation Mechanisms of Coffee Brew Melanoidins. J. Agric. Food Chem. 2008, 56, 7138– 7145, DOI: 10.1021/jf800999a
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Roasting effects on formation mechanisms of coffee brew melanoidins
Bekedam, E. Koen; Loots, Mirjam J.; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
Journal of Agricultural and Food Chemistry (2008), 56 (16), 7138-7145CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The effect of the roasting degree on coffee brew melanoidin properties and formation mechanisms was studied. Coffee brew fractions differing in mol. wt. (Mw) were isolated from green and light-, medium-, and dark-roasted coffee beans. Isolated fractions were characterized for their melanoidin, nitrogen, protein, phenolic groups, chlorogenic acid, quinic acid, caffeic acid, and sugar content. It was found that the melanoidin level in all fractions correlated with both the nitrogen and the protein content. The melanoidin level also correlated with the phenolic groups' level and ester-linked quinic acid level. It was concluded that proteins and chlorogenic acids should be primarily involved in melanoidin formation. Initial roasting, from green to light-roasted beans, esp. led to the formation of intermediate Mw (IMw) melanoidins when compared to high Mw (HMw) melanoidins. Indications were found that this IMw melanoidin formation is mainly due to Maillard reactions and chlorogenic acid incorporation reactions between chlorogenic acids, sucrose, and amino acids/protein fragments. Addnl., it was found that prolonged roasting predominantly led to formation melanoidins with a high Mw. Furthermore, arabinogalactans seem to be relatively more involved in melanoidin formation than galactomannans. It was hypothesized that chromophores may be formed or attached through the arabinose moiety of arabinogalactan proteins (AGP). Finally, it could be concluded that galactomannans are continuously incorporated in AGP-melanoidins upon roasting.
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Oosterveld, A.; Harmsen, J. S.; Voragen, A. G. J.; Schols, H. A. Extraction and Characterization of Polysaccharides from Green and Roasted Coffea Arabica Beans. Carbohydr. Polym. 2003, 52, 285– 296, DOI: 10.1016/S0144-8617(02)00296-5
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Extraction and characterization of polysaccharides from green and roasted Coffea arabica beans
Oosterveld, A.; Harmsen, J. S.; Voragen, A. G. J.; Schols, H. A.
Carbohydrate Polymers (2003), 52 (3), 285-296CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Science Ltd.)
Polysaccharides were sequentially extd. from green and roasted Coffea arabica beans with water (90°), EDTA, 0.05, 1, and 4 M NaOH and characterized chem. Addnl., the beans were subjected to a single extn. with water at 170°. Green arabica coffee beans contained large proportions of 1→4-linked mannans, of which on av. 1 in every 23 mannopyranose residues was branched with single unit galactose side-chains at O-6. A part of these galactomannans could be extd. relatively easy with water and EDTA. These galactomannans were found to have a relatively high degree of branching (gal:man∼1:8) and a relatively low mol. wt. in comparison to the remaining galactomannans (gal:man∼1:15-24). Addnl., 1 3-linked galactans, heavily branched at O-6 with side-chains contg. arabinose and galactose residues, were present in the green coffee beans, as well as smaller amts. of pectins, cellulose, and xyloglucans. Roasting resulted in a loss of 8% of the dry wt. This could be partly explained by the relatively high percentage of sugars which was lost during the roasting process, most probably as a result of conversion into, e.g. Maillard and pyrolysis products. After roasting the extractability of polysaccharides was increased significantly. A decrease in the degree of branching as well as a decrease in mol. wt. of arabinogalactans, galactomannans, and xyloglucans was obsd. after roasting.
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Tagliazucchi, D.; Verzelloni, E. Relationship between the Chemical Composition and the Biological Activities of Food Melanoidins. Food Sci. Biotechnol. 2014, 23, 561– 568, DOI: 10.1007/s10068-014-0077-5
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Relationship between the chemical composition and the biological activities of food melanoidins
Tagliazucchi, Davide; Verzelloni, Elena
Food Science and Biotechnology (2014), 23 (2), 561-568CODEN: FSBOBR; ISSN:1226-7708. (Korean Society of Food Science and Technology)
The relationship between the chem. compn. and the biol. activities of food melanoidin-rich fractions was investigated. Melanoidin-rich fractions were extd. using ultrafiltration (a 10 kDa cut-off) from coffee, barley coffee, dark beer, and traditional balsamic vinegar. All the food melanoidin-rich fractions were formed mainly of carbohydrates, phenolic compds., and proteins. In dark beer, barley coffee, and traditional balsamic vinegar melanoidins, glucose was the most abundant sugar incorporated into melanoidins. Coffee melanoidins contained the largest amt. of phenolic groups, followed by traditional balsamic vinegar melanoidins. The radical scavenging, Fe2+-chelating, and heme binding abilities of food melanoidins were investigated under gastric conditions. The melanoidin rich fraction extd. from coffee was the most active, showing the highest radical scavenging, Fe2+-chelating, and heme binding activities, compared to barley coffee, dark beer, and traditional balsamic vinegar. The radical scavenging and Fe2+-chelating abilities were assigned to the phenolic groups present in food melanoidins.
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Lopes, G. R.; Ferreira, A. S.; Pinto, M.; Passos, C. P.; Coelho, E.; Rodrigues, C.; Figueira, C.; Rocha, S. M.; Nunes, F. M.; Coimbra, M. A. Carbohydrate Content, Dietary Fibre and Melanoidins: Composition of Espresso from Single-Dose Coffee Capsules. Food Res. Int. 2016, 89, 989– 996, DOI: 10.1016/j.foodres.2016.01.018
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Carbohydrate content, dietary fibre and melanoidins: Composition of espresso from single-dose coffee capsules
Lopes, Guido R.; Ferreira, Andreia S.; Pinto, Mariana; Passos, Claudia P.; Coelho, Elisabete; Rodrigues, Carla; Figueira, Claudia; Rocha, Silvia M.; Nunes, Fernando M.; Coimbra, Manuel A.
Food Research International (2016), 89 (Part_2), 989-996CODEN: FORIEU; ISSN:0963-9969. (Elsevier B.V.)
Single-dose coffee capsule system is a technol. used to prep. espresso coffee which offers consumers the possibility to choose among several blends. However, the characterization of espresso coffees extd. with these systems, namely regarding polysaccharides structures and melanoidin content, is scarce. In order to define a carbohydrate and melanoidin compn. pattern for single-dose espresso coffee base blends, a range of 6 com. espresso coffee blends was studied. In addn., a decaffeinated blend and a blend supplemented with plant natural exts. were also included. The base blends showed galactomannans as the predominant polysaccharides over arabinogalactans, on the contrary of the decaffeinated blend. The blend supplemented with natural plant exts. showed glucose-rich polysaccharides. The labeled intensity of coffee single-dose seems to be related with the unknown brown compds. of melanoidins, present in the high mol. wt. material of the brews. A pattern could be obtained for single-dose espresso coffee base blends, presenting an av. per cup of 1.21 g of total solids and 242 mg of sol. dietary fiber, constituted by 62 mg of galactomannans and 48 mg of arabinogalactans, and 123 mg of melanoidins. On av., 46% of espresso coffee low mol. wt. compds. are adsorbed to the high mol. wt. material, evidencing the importance of the adsorption/desorption phenomena for the properties of coffee dietary fiber.
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Nunes, F. M.; Coimbra, M. A. Chemical Characterization of the High Molecular Weight Material Extracted with Hot Water from Green and Roasted Arabica Coffee. J. Agric. Food Chem. 2001, 49, 1773– 1782, DOI: 10.1021/jf0012953
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Chemical Characterization of the High Molecular Weight Material Extracted with Hot Water from Green and Roasted Arabica Coffee
Nunes, Fernando M.; Coimbra, Manuel A.
Journal of Agricultural and Food Chemistry (2001), 49 (4), 1773-1782CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The polysaccharides present in coffee infusions are known to contribute to the organoleptic characteristics of the drink, such as the creamy sensation perceived in the mouth known as "body", the release of aroma substances, and the stability of espresso coffee foam. To increase the knowledge about the origin, compn., and structure of the polysaccharide fraction, the high mol. wt. material (HMWM) was extd. with hot water from 2 green and roasted ground arabica coffees: Costa Rica (wet processed) and Brazil (dry processed). The polysaccharides present in the green coffees HMWM were arabinogalactans (62%), galactomannans (24%), and glucans, and those found in roasted coffees were galactomannans (69%) and arabinogalactans (28%). The polysaccharides of the HMWM of the roasted coffees were less branched than those of the green coffees. The major green coffee proteins had mol. wts. of 58 and 38 kDa, and the 58 kDa protein had two subunits, of 38 and 20 kDa, possibly linked by disulfide bonds. The protein fraction obtained from roasted coffees had only a defined band with ≤14 kDa and a diffuse band with >200 kDa. The majority of the galactomannans were pptd. with solns. of 50% ethanol, and the size-exclusion chromatog. of the roasted fractions showed Co-elution of polysaccharides, proteins, phenolics, and brown compds. The use of strong hydrogen and hydrophobic dissocn. conditions allowed us to conclude that the phenolics and brown compds. were linked by covalent bonds to the polymeric material.
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Simões, J.; Moreira, A. S. P.; Passos, C. P.; Nunes, F. M.; Domingues, M. R. M.; Coimbra, M. A. CHAPTER 19. Polysaccharides and Other Carbohydrates. In Coffee: Production, Quality and Chemistry; The Royal Society of Chemistry, 2019, pp 445– 457.
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Moreira, A. S. P.; Simões, J.; Pereira, A. T.; Passos, C. P.; Nunes, F. M.; Domingues, M. R. M.; Coimbra, M. A. Transglycosylation Reactions between Galactomannans and Arabinogalactans during Dry Thermal Treatment. Carbohydr. Polym. 2014, 112, 48– 55, DOI: 10.1016/j.carbpol.2014.05.031
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Transglycosylation reactions between galactomannans and arabinogalactans during dry thermal treatment
Moreira, Ana S. P.; Simoes, Joana; Pereira, Andreia T.; Passos, Claudia P.; Nunes, Fernando M.; Domingues, M. Rosario M.; Coimbra, Manuel A.
Carbohydrate Polymers (2014), 112 (), 48-55CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)
Aiming to investigate the possible occurrence of transglycosylation reactions between galactomannans and side chains of arabinogalactans during coffee roasting, mixts. of β-(1→4)-D-mannotriose and α-(1→5)-L-arabinotriose were subjected to dry thermal treatments at 200 °C. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) anal. allowed identifying polysaccharides composed by pentose and hexose residues with a d.p. up to 18 residues. Methylation anal. showed the occurrence of new types of glycosidic linkages in all thermally treated mixts., as well as the occurrence of terminally and 5-linked ribose, possibly formed from arabinose isomerization. Also, xylose and lyxose were identified and proposed to be formed from mannose. These results support the occurrence of transglycosylation reactions promoted by roasting involving both oligosaccharides in the starting mixts., resulting in arabinan and mannan chimeric polysaccharides. These structural features were also found in roasted coffee polysaccharide samples.
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Ludwig, I. A.; Clifford, M. N.; Lean, M. E. J.; Ashihara, H.; Crozier, A. Coffee: Biochemistry and Potential Impact on Health. Food Funct. 2014, 5, 1695– 1717, DOI: 10.1039/c4fo00042k
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Coffee: biochemistry and potential impact on health
Ludwig, Iziar A.; Clifford, Michael N.; Lean, Michael E. J.; Ashihara, Hiroshi; Crozier, Alan
Food & Function (2014), 5 (8), 1695-1717CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
This review provides details on the phytochems. in green coffee beans and the changes that occur during roasting. Key compds. in the coffee beverage, produced from the ground, roasted beans, are volatile constituents responsible for the unique aroma, the alkaloids caffeine and trigonelline, chlorogenic acids, the diterpenes cafestol and kahweol, and melanoidins, which are Maillard reaction products. The fate of these compds. in the body following consumption of coffee is discussed along with evidence of the mechanisms by which they may impact health. Finally, epidemiol. findings linking coffee consumption to potential health benefits including prevention of several chronic and degenerative diseases, such as cancer, cardiovascular disorders, diabetes, and Parkinson's disease, are evaluated.
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Bekedam, E. K.; Roos, E.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Low Molecular Weight Melanoidins in Coffee Brew. J. Agric. Food Chem. 2008, 56, 4060– 4067, DOI: 10.1021/jf8001894
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Low molecular weight melanoidins in coffee brew
Bekedam, E. Koen; Roos, Ellen; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
Journal of Agricultural and Food Chemistry (2008), 56 (11), 4060-4067CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Anal. of low mol. wt. (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate anal. This study focused on the isolation of LMw coffee brew melanoidins by sepn. of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extn. and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were detd. The sugar compn., the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic anal. revealed that the melanoidins isolated showed similar features as high mol. wt. coffee melanoidins. All three melanoidin fractions contained ∼3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a neg. charge, and this neg. charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins.
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Wei, F.; Tanokura, M. Chemical Changes in the Components of Coffee Beans during Roasting. Coffee in Health and Disease Prevention; Elsevier Inc., 2015.
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There is no corresponding record for this reference.
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Ludwig, I. A.; Mena, P.; Calani, L.; Cid, C.; Del Rio, D.; Lean, M. E. J.; Crozier, A. Variations in Caffeine and Chlorogenic Acid Contents of Coffees: What Are We Drinking?. Food Funct. 2014, 5, 1718– 1726, DOI: 10.1039/c4fo00290c
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Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking?
Ludwig, Iziar A.; Mena, Pedro; Calani, Luca; Cid, Concepcion; Del Rio, Daniele; Lean, Michael E. J.; Crozier, Alan
Food & Function (2014), 5 (8), 1718-1726CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
The effect of roasting of coffee beans and the extn. of ground coffee with different vols. of hot pressurised water on the caffeine and the total caffeoylquinic acids (CQAs) content of the resultant beverages was investigated. While caffeine was stable higher roasting temps. resulted in a loss of CQAs so that the caffeine/CQA ratio was a good marker of the degree of roasting. The caffeine and CQA content and vol. was detd. for 104 espresso coffees obtained from coffee shops in Scotland, Italy and Spain, limited nos. of cappuccino coffees from com. outlets and several instant coffees. The caffeine content ranged from 48-317 mg per serving and CQAs from 6-188 mg. It is evident that the ingestion of 200 mg of caffeine per day can be readily and unwittingly exceeded by regular coffee drinkers. This is the upper limit of caffeine intake from all sources recommended by US and UK health agencies for pregnant women. In view of the variable vol. of serving sizes, it is also clear that the term "one cup of coffee" is not a reproducible measurement for consumption, yet it is the prevailing unit used in epidemiol. to assess coffee consumption and to link the potential effects of the beverage and its components on the outcome of diseases. More accurate measurement of the intake of coffee and its potentially bioactive components are required if epidemiol. studies are to produce more reliable information.
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Bekedam, E. K.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Incorporation of Chlorogenic Acids in Coffee Brew Melanoidins. J. Agric. Food Chem. 2008, 56, 2055– 2063, DOI: 10.1021/jf073157k
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Incorporation of chlorogenic acids in coffee brew melanoidins
Bekedam, E. Koen; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
Journal of Agricultural and Food Chemistry (2008), 56 (6), 2055-2063CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The incorporation of chlorogenic acids (CGAs) and their subunits quinic and caffeic acids (QA and CA) in coffee brew melanoidins was studied. Fractions with different mol. wts., ionic charges, and ethanol solubilities were isolated from coffee brew. Fractions were sapond., and the released QA and CA were quantified. For all melanoidin fractions, it was found that more QA than CA was released. QA levels correlated with melanoidin levels, indicating that QA is incorporated in melanoidins. The QA level was correlated with increasing ionic charge of the melanoidin populations, suggesting that QA may contribute to the neg. charge and consequently is, most likely, not linked via its carboxyl group. The QA level correlated with the phenolic acid group level, as detd. by Folin-Ciocalteu, indicating that QA was incorporated to a similar extent as the polyphenolic moiety from CGA. The QA and CA released from brew fractions by enzymes confirmed the incorporation of intact CGAs. Intact CGAs are proposed to be incorporated in melanoidins upon roasting via CA through mainly nonester linkages. This complex can be written as Mel=CA-QA, in which Mel represents the melanoidin backbone, =CA represents CA nonester-linked to the melanoidin backbone, and -QA represents QA ester-linked to CA. Addnl., a total of 12% of QA was identified in coffee brew, whereas only 6% was reported in the literature so far. The relevance of the addnl. QA on coffee brew stability is discussed.
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Silván, J. M.; Morales, F. J.; Saura-Calixto, F. Conceptual Study on Maillardized Dietary Fiber in Coffee. J. Agric. Food Chem. 2010, 58, 12244– 12249, DOI: 10.1021/jf102489u
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Conceptual study on Maillardized dietary fiber in coffee
Silvan, Jose Manuel; Morales, Francisco J.; Saura-Calixto, Fulgencio
Journal of Agricultural and Food Chemistry (2010), 58 (23), 12244-12249CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
There is a methodol. and conceptual overlap between coffee melanoidins and dietary fiber. Green Uganda coffee beans were roasted in a range from 8.1 to 21.6% of wt. loss to evaluate melanoidins and dietary fiber. Samples were characterized by color, moisture, soly., water activity, carbohydrates, polyphenols, protein, sol. dietary fiber (SDF), and melanoidins content. Hydroxymethylfurfural and chlorogenic acids were also measured as chem. markers of the extent of roasting. Melanoidins rapidly increased from 5.6 (light roasting) to 29.1 mg/100 mg sol. dry matter (dark roasting). A melanoidins-like structure was already present in green coffee that might overestimate up to 21.0% of the melanoidins content as detd. by colorimetric methods. However, its contribution is variable and very likely depends on the method of drying applied to green coffee. SDF content (mg/100 mg sol. dry matter) gradually increased from 39.4 in green coffee to 64.9 at severe roasting conditions due to incorporation of neoformed colored structures and polyphenols. Then, SDF progressively turns to a maillardized structure, which increased from 11.0 to 45.0% according to the roasting conditions. It is concluded that the content of coffee melanoidins includes a substantial part of dietary fiber and also that coffee dietary fiber includes melanoidins. A conceptual discussion on a new definition of coffee melanoidins as a type of maillardized dietary fiber is conducted.
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Schröder, A.; Berton-Carabin, C.; Venema, P.; Cornacchia, L. Interfacial Properties of Whey Protein and Whey Protein Hydrolysates and Their Influence on O/W Emulsion Stability. Food Hydrocolloids 2017, 73, 129– 140, DOI: 10.1016/j.foodhyd.2017.06.001
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There is no corresponding record for this reference.
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Redgwell, R. J.; Schmitt, C.; Beaulieu, M.; Curti, D. Hydrocolloids from Coffee: Physicochemical and Functional Properties of an Arabinogalactan-Protein Fraction from Green Beans. Food Hydrocolloids 2005, 19, 1005– 1015, DOI: 10.1016/j.foodhyd.2004.12.010
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Hydrocolloids from coffee: physicochemical and functional properties of an arabinogalactan-protein fraction from green beans
Redgwell, R. J.; Schmitt, C.; Beaulieu, M.; Curti, D.
Food Hydrocolloids (2005), 19 (6), 1005-1015CODEN: FOHYES; ISSN:0268-005X. (Elsevier B.V.)
The arabinogalactan-protein (AGP) fraction of green coffee beans accounts for ∼15% of the dry bean. A procedure was developed to solubilize most of the AGP content of the beans so that its properties as a hydrocolloid could be investigated. An AGP fraction was partially purified from green arabica coffee beans, its rheol. properties characterized and compared to those of some com. important hydrocolloids, particularly acacia gum. The coffee AGP fraction dissolved readily in water to give colorless clear solns. The polymer was a polyelectrolyte with a high mol. wt. (Mw 3.78×106), characterized by a narrow polydispersity index (Mw/Mn 1.3). The intrinsic viscosity was close to that of acacia gum ([η]=0.23 dL g-1), but a 1 wt% soln. of coffee AGP was three times more viscous than acacia gum at the same concn. Coffee AGP showed Newtonian flow for concns. below 6 wt%, but above this concn. the flow behavior entered a shear-thinning regime. The coffee AGP fraction possessed interesting foaming properties providing that the biopolymer concn. was high enough to initially stabilize the interface that is created. The high mol. wt. of coffee AGP combined with its globular structure conferred upon it a high ability to retain water within a foam thin film. However, the structure of the interfacial film was less effective than that of acacia gum to entrap efficiently the gas into the foam. In summary, coffee AGP shows some interesting rheol. features which suggest that coffee beans could be used as an alternative source of the class of surface-active polymers which find many com. applications.
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St. Angelo, A. J.; Vercellotti, J.; Jacks, T.; Legendre, M. Lipid Oxidation in Foods; American Chemical Society, 1996; Vol. 36.
Google Scholar
There is no corresponding record for this reference.
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Chen, B.; McClements, D. J.; Decker, E. A. Minor Components in Food Oils: A Critical Review of Their Roles on Lipid Oxidation Chemistry in Bulk Oils and Emulsions. Crit. Rev. Food Sci. Nutr. 2011, 51, 901– 916, DOI: 10.1080/10408398.2011.606379
Google Scholar
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Minor Components in Food Oils: A Critical Review of their Roles on Lipid Oxidation Chemistry in Bulk Oils and Emulsions
Chen, Bingcan; McClements, David Julian; Decker, Eric Andrew
Critical Reviews in Food Science and Nutrition (2011), 51 (10), 901-916CODEN: CRFND6; ISSN:1040-8398. (Taylor & Francis, Inc.)
A review. Food oils are primarily composed of triacylglycerols (TAG), but they may also contain a variety of other minor constituents that influence their phys. and chem. properties, including diacylglycerols (DAG), monoacylglycerols (MAG), free fatty acids (FFA), phospholipids (PLs), water, and minerals. This article reviews recent research on the impact of these minor components on lipid oxidn. in bulk oils and oil-in-water emulsions. In particular, it highlights the origin of these minor components, the influence of oil refining on the type and concn. of minor components present, and potential physicochem. mechanisms by which these minor components impact lipid oxidn. in bulk oils and emulsions. This knowledge is crucial for designing food, pharmaceutical, personal care, and other products with improved stability to lipid oxidn.
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Tian, L.; Kejing, K.; Zhang, S.; Yi, J.; Zhu, Z.; Decker, E. A.; McClements, D. J. Impact of Tea Polyphenols on the Stability of Oil-in-Water Emulsions Coated by Whey Proteins. Food Chem. 2021, 343, 128448, DOI: 10.1016/j.foodchem.2020.128448
Google Scholar
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Impact of tea polyphenols on the stability of oil-in-water emulsions coated by whey proteins
Tian, Li; Yang, Kejing; Zhang, Shulin; Yi, Jianhua; Zhu, Zhenbao; Decker, Eric Andrew; McClements, David Julian
Food Chemistry (2021), 343 (), 128448CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
The ability of tea polyphenols (0, 0.01, 0.02 or 0.04 w/v %) to inhibit lipid and protein oxidn. in walnut oil-in-water (O/W) emulsions was examd., as well as to alter their stability to aggregation and creaming. The lipid droplets in these emulsions were coated by whey proteins. The phys. stability of the emulsions during storage (50°C, 96 h) was improved by addn. of 0.01% tea polyphenols, but reduced when higher levels were added. Low levels (0.01%) of tea polyphenols inhibited lipid oxidn. (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidn. (carbonyl and Schiff base formation, sulfhydryl and intrinsic fluorescence loss, and mol. wt. changes). However, high levels (0.04%) of tea polyphenols were less effective at inhibiting lipid oxidn., and actually promoted protein oxidn. Tea polyphenols are natural antioxidants that can enhance the quality and shelf life of emulsified polyunsatd. lipids when used at an appropriate concn.
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Faraji, H.; McClements, D. J.; Decker, E. A. Role of Continuous Phase Protein on the Oxidative Stability of Fish Oil-in-Water Emulsions. J. Agric. Food Chem. 2004, 52, 4558– 4564, DOI: 10.1021/jf035346i
Google Scholar
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Role of Continuous Phase Protein on the Oxidative Stability of Fish Oil-in-Water Emulsions
Faraji, Habibollah; McClements, D. Julian; Decker, Eric A.
Journal of Agricultural and Food Chemistry (2004), 52 (14), 4558-4564CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidn. when they produce a pos. charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the continuous phase. The impact of these continuous phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepd. by high-pressure homogenization. In some expts. WPI was removed from the continuous phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that continuous phase proteins were antioxidative. The oxidative stability of emulsions contg. different kinds of protein in the continuous phase decreased in the order SPI > CAS > WPI, as detd. by both hydroperoxide and headspace propanal formation. Iron-binding studies showed that the chelating ability of the proteins decreased in the order CAS > SPI > WPI. The free sulfhydryls of both WPI and SPI were involved in their antioxidant activity. This research shows that continuous phase proteins could be an effective means of protecting ω-3 fatty acids from oxidative deterioration.
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Kaushik, P.; Dowling, K.; McKnight, S.; Barrow, C. J.; Wang, B.; Adhikari, B. Preparation, Characterization and Functional Properties of Flax Seed Protein Isolate. Food Chem. 2016, 197, 212– 220, DOI: 10.1016/j.foodchem.2015.09.106
Google Scholar
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Preparation, characterization and functional properties of flax seed protein isolate
Kaushik, Pratibha; Dowling, Kim; McKnight, Stafford; Barrow, Colin J.; Wang, Bo; Adhikari, Benu
Food Chemistry (2016), 197 (Part_A), 212-220CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
Flaxseed protein isolate (FPI) was extd. from flaxseeds, and its amino acid compn. and functional properties (soly., thermal stability, emulsifying properties and electrostatic charge d., water-holding and fat-absorption capacities) were detd. The highest purity of FPI (90.6%) was achieved by extn. at 60 °C. FPI had a low lysine to arginine ratio of 0.25, which is desired in heart-healthy foods and infant formulas. The denaturation temp. of FPI was 105 °C. FPI had the highest emulsion activity index (375.51 m2/g), highest emulsion stability index (179.5 h) and zeta potential (-67.4 mV) when compared to those of other commonly used proteins, such as sodium caseinate (SC), whey protein isolate (WPI), gelatin (Gel) and soy protein isolate (SPI). The av. emulsion droplet size of emulsions stabilized by these proteins was in the order SC < FPI < WPI < Gel < SPI. Water-holding and fat-absorption capacities of FPI were similar to those of the above-mentioned proteins.
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Borrelli, R. C.; Visconti, A.; Mennella, C.; Anese, M.; Fogliano, V. Chemical Characterization and Antioxidant Properties of Coffee Melanoidins. J. Agric. Food Chem. 2002, 50, 6527– 6533, DOI: 10.1021/jf025686o
Google Scholar
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Chemical Characterization and Antioxidant Properties of Coffee Melanoidins
Borrelli, Rosa Cinzia; Visconti, Attilio; Mennella, Carmela; Anese, Monica; Fogliano, Vincenzo
Journal of Agricultural and Food Chemistry (2002), 50 (22), 6527-6533CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Melanoidins, the brown polymers formed through Maillard reaction during coffee roasting, constitute up to 25% of the coffee beverages' dry matter. In this study chem. characterization of melanoidins obtained from light-, medium-, and dark-roasted coffee beans, manufd. from the same starting material, was performed. Melanoidins were sepd. by gel filtration chromatog. and studied by MALDI-TOF mass spectrometry. Results showed that the amt. of melanoidins present in the brews increased as the intensity of the thermal treatment increased, while their mol. wt. decreased. The antioxidant activity of melanoidins isolated from the different brews was studied by using different methodologies. Melanoidins antiradical activity detd. by ABTS•+ and DMPD•+ assays decreased as the intensity of roasting increased, but the ability to prevent linoleic acid peroxidn. was higher in the dark-roasted samples. Data suggest that melanoidins must be carefully considered when the relevance of coffee intake in human health is studied.
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Wang, H. Y.; Qian, H.; Yao, W. R. Melanoidins Produced by the Maillard Reaction: Structure and Biological Activity. Food Chem. 2011, 128, 573– 584, DOI: 10.1016/j.foodchem.2011.03.075
Google Scholar
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Melanoidins produced by the Maillard reaction: Structure and biological activity
Wang, He-Ya; Qian, He; Yao, Wei-Rong
Food Chemistry (2011), 128 (3), 573-584CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
A review. Melanoidins are compds. generated in the late stages of the Maillard reaction from reducing sugars and proteins or amino acids during food processing and preservation. Recently the effects of melanoidins on human health and the chem. characterization of the beneficial components have gained a lot of attention. Food melanoidins have been reported to be anionic, colored compds. and some of their key chromophores have been elucidated. The antioxidant activity and other biol. effects of melanoidins from real foods and model systems have been widely studied. Despite this, very few different melanoidin structures have actually been described, and specific health effects have yet to be linked to chem. distinct melanoidins. The variety of different Maillard reaction products formed during the reaction, in conjunction with the difficulty in purifying and identifying them, makes a thorough anal. of melanoidins challenging. This review provides a comprehensive look at what is known to date about melanoidin structure, the formation mechanism for these compds., and the biol. properties related to the beneficial health effects of melanoidins.
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Kim, J. Y.; Kim, S.; Han, S.; Han, S. Y.; Passos, C. P.; Seo, J.; Lee, H.; Kang, E. K.; Mano, J. F.; Coimbra, M. A.; Park, J. H.; Choi, I. S. Coffee Melanoidin-Based Multipurpose Film Formation: Application to Single-Cell Nanoencapsulation. ChemNanoMat 2020, 6, 379– 385, DOI: 10.1002/cnma.202000004
Google Scholar
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Coffee Melanoidin-Based Multipurpose Film Formation: Application to Single-Cell Nanoencapsulation
Kim, Ji Yup; Kim, Seulbi; Han, Sol; Han, Sang Yeong; Passos, Claudia P.; Seo, Jeongyeon; Lee, Hojae; Kang, Eunhye K.; Mano, Joao F.; Coimbra, Manuel A.; Park, Ji Hun; Choi, Insung S.
ChemNanoMat (2020), 6 (3), 379-385CODEN: CHEMSB; ISSN:2199-692X. (Wiley-VCH Verlag GmbH & Co. KGaA)
The melanoidin from sol. coffee is utilized as a material-independent, multipurpose coating material. Instantaneous complexation of the coffee melanoidin (CM) with ferric ion (Fe3+) leads to surface-adhesive aggregates, inducing sequential film deposition. Various chem. groups of the CM also allow for post-functionalizations of the CM film, including surface-initiated, ring-opening polymn. and bioinspired silicification. In addn., the CM-based coating is applied to single-cell nanoencapsulation with a strategy of biphasic interfacial reactions. The method is highly cytocompatible (viability >98%), and the CM shell is cytoprotective against lytic enzymes. The coated cells inherit the characterictics of the CM, such as post-functionalizability and antioxidant property. Considering that surface-coating technologies with cytocompatible natural polymers have widely been used for engineering bioentities, the CM-based coating strategy would provide an advanced option for biomedical applications.
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Troup, G. J.; Navarini, L.; Liverani, F. S.; Drew, S. C. Stable Radical Content and Anti-Radical Activity of Roasted Arabica Coffee: From in-Tact Bean to Coffee Brew. PLoS One 2015, 10, e0122834 DOI: 10.1371/journal.pone.0122834
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Stable radical content and anti-radical activity of roasted arabica coffee: from in-tact bean to coffee brew
Troup, Gordon J.; Navarini, Luciano; Liverani, Furio Suggi; Drew, Simon C.
PLoS One (2015), 10 (4), e0122834/1-e0122834/17CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
The roasting of coffee beans generates stable radicals within melanoidins produced by non-enzymic browning. Roasting coffee beans has further been suggested to increase the antioxidant (AO) capacity of coffee brews. Herein, we have characterized the radical content and AO capacity of brews prepd. from Coffea arabica beans sourced directly from an industrial roasting plant. In-tact beans exhibited ESR signals arising from Fe3+, Mn2+ and at least three distinct stable radicals as a function of roasting time, whose intensity changed upon grinding and ageing. In coffee brews, the roasting-induced radicals were harboured within the high mol. wt. (> 3 kD) melanoidin- contg. fraction at a concn. of 15 nM and was assocd. with arom. groups within the melanoidins. The low mol. wt. (< 3 kD) fraction exhibited the highest AO capacity using DPPH as an oxidant. The AO activity was not mediated by the stable radicals or by metal complexes within the brew. While other non-AO functions of the roasting-induced radical and metal complexes may be possible in vivo, we confirm that the in vitro antiradical activity of brewed coffee is dominated by low mol. wt. phenolic compds.
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Samsonowicz, M.; Regulska, E.; Karpowicz, D.; Leśniewska, B. Antioxidant Properties of Coffee Substitutes Rich in Polyphenols and Minerals. Food Chem. 2019, 278, 101– 109, DOI: 10.1016/j.foodchem.2018.11.057
Google Scholar
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Antioxidant properties of coffee substitutes rich in polyphenols and minerals
Samsonowicz, Mariola; Regulska, Ewa; Karpowicz, Danuta; Lesniewska, Barbara
Food Chemistry (2019), 278 (), 101-109CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
The anal. of general content of polyphenols, minerals and antioxidant activity of infusions from selected coffee substitutes is presented. The obtained results showed that the coffee infusions prepd. from acorns exhibit the highest radical scavenging capacities for DPPH (EC50 = 0.063-0.066 mgd.w./mL), ABTS (EC50 = 0.021-0.029 mgd.w./mL), OH·(EC50 = 2.050-2.378 mgd.w./mL) as well as the highest ability to Fe3+ redn. (FRAP) (∼1.1 mmolFe/gd.w). These coffee substitutes also contain the greatest values of polyphenols (45-50 mgGA/gd.w). Analyzed coffee substitutes differ in both quality and quantity of polyphenols, but all tested coffees contain gallic and chlorogenic acids. The most of phenolic compds. was found in herbal-cereal coffee substitute. The quant. results and PCA anal. indicated a good correlation between the antioxidant activity and total polyphenols, flavonoids and gallic acid content. Using the obtained data on the compn. and antioxidant properties of exts. the cluster anal. (CA) was performed to distinguish similar or close types of coffee.
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Laguerre, M.; Tenon, M.; Bily, A.; Birtić, S. Toward a Spatiotemporal Model of Oxidation in Lipid Dispersions: A Hypothesis-Driven Review. Eur. J. Lipid Sci. Technol. 2020, 122, 1900209, DOI: 10.1002/ejlt.201900209
Google Scholar
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Toward a Spatiotemporal Model of Oxidation in Lipid Dispersions: A Hypothesis-Driven Review
Laguerre, Mickael; Tenon, Mathieu; Bily, Antoine; Birtic, Simona
European Journal of Lipid Science and Technology (2020), 122 (3), 1900209CODEN: EJLTFM; ISSN:1438-7697. (Wiley-VCH Verlag GmbH & Co. KGaA)
Unsatd. lipids are prone to get oxidized through a sequence of reactions known as lipid oxidn. From a phenomenon considered at the beginning as a mere chem. process and described by the triptych of initiation, propagation, and termination, the vision of lipid oxidn. has progressively evolved to further integrate the phys. dimension of the phenomenon. Despite tremendous research efforts, however, this sequence of reactions is not yet well understood, esp. in lipid dispersions where many facts are still inexplicable and unpredictable under the current paradigm. Here, the aim is to suggest that the main reason why a better understanding has not already been achieved is that the reactional network is not yet organized in a coherent spatiotemporal framework. The novel concepts and hypotheses proposed in this article may help redirecting a significant part of research efforts toward the establishment of a spatially and temporally resolved model of oxidn. in dispersed lipids. Practical Application: Predicting how oxidn. spreads in lipid dispersions represents a goal of crucial importance for academia but also for industry. Such prediction models would indeed greatly help food manufacturers prevent oxidn. by using the most adapted antioxidative strategies for their specific products. To achieve such an objective, it is proposed that the first thing to do is to go beyond the extremely reductive and narrow framework in which this chem. process has been locked in. Indeed, while lipid dispersions are composed of a multitude of lipid colloids, researchers usually consider oxidn. at the sole level of an individual droplet or membrane. Instead, lipid oxidn. is advocated as a dynamic trafficking of chem. species within large communities of different colloidal objects such as droplets, membranes, or micelles dispersed in water-a system that dubbed "colloidal ecosystem". This might represent a scale complementary to the scales of individual colloids or mols. that were the sole consideration so far to try torepresent lipid oxidn. Only then can one hope to effectively apply modeling and "omics" approaches, as is explained in more details in this article.
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Morales, F. J.; Jiménez-Pérez, S. Peroxyl Radical Scavenging Activity of Melanoidins in Aqueous Systems. Eur. Food Res. Technol. 2004, 218, 515– 520, DOI: 10.1007/s00217-004-0896-3
Google Scholar
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Peroxyl radical scavenging activity of melanoidins in aqueous systems
Morales, Francisco J.; Jimenez-Perez, Salvio
European Food Research and Technology (2004), 218 (6), 515-520CODEN: EFRTFO; ISSN:1438-2377. (Springer-Verlag)
Melanoidins are widely distributed in our diet, due to home or industrial processing of foods. Until recently, melanoidins were considered to be an inert, brown-colored polymeric component. However, recent research into their nutritional, physiol., and functional properties has suggested that they have antioxidant properties, and we address this issue in this work. A sensitive procedure for assessing the inhibition of lipid peroxidn. by melanoidins in watery media has been developed. Main drawbacks and crit. steps of the procedure are discussed. Melanoidins can be classified according to the no. of peroxyl radicals trapped per mol. Coffee and sweet wine melanoidins show higher antioxidant activity than melanoidins isolated from beer. For the first time, a linear relationship between the peroxyl radical scavenging activity and the chromophore residues in the melanoidin skeleton responsible for browning has been established.
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Pérez-Martínez, M.; Caemmerer, B.; De Peña, M. P.; Cid, C.; Kroh, L. W. Influence of Brewing Method and Acidity Regulators on the Antioxidant Capacity of Coffee Brews. J. Agric. Food Chem. 2010, 58, 2958– 2965, DOI: 10.1021/jf9037375
Google Scholar
59
Influence of Brewing Method and Acidity Regulators on the Antioxidant Capacity of Coffee Brews
Perez-Martinez, Monica; Caemmerer, Bettina; De Pena, M. Paz; Cid, Concepcion; Kroh, Lothar W.
Journal of Agricultural and Food Chemistry (2010), 58 (5), 2958-2965CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The antioxidant capacity of coffee brews prepd. with different coffeemakers (filter, plunger, mocha, and espresso) was measured by colorimetric (total phenolic compds. and ABTS) and ESR spectroscopy techniques (Fremy's salt and TEMPO). The mocha coffeemaker had the highest yield in coffee antioxidant extn. per g of ground roasted coffee, but espresso coffee was richest in terms of antioxidant intake (per milliliter of coffee brew) followed by mocha, plunger, and filter. Both Folin-Ciocalteu (total phenolic compds.) and ABTS assays reacted with std. solns. of chlorogenic acids (CGA) and melanoidins (MO-Ala and MO-Gly). However, Fremy's salt was mainly scavenged by chlorogenic acids, whereas the stabilized radical TEMPO was effectively scavenged by melanoidins, but not by chlorogenic acids. Thus, ESR spectroscopy allows distinguishing between phenolic and nonphenolic antioxidants. Moreover, the addn. of pH-regulator agents to coffee, such as sodium carbonate (75 ppm) and bicarbonate (75 ppm), to extend its shelf life, slightly increases the pH, modifying the antioxidant capacity in those coffee brews with the highest capacity (mocha and espresso).
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Kellerby, S. S.; McClements, D. J.; Decker, E. A. Role of Proteins in Oil-in-Water Emulsions on the Stability of Lipid Hydroperoxides. J. Agric. Food Chem. 2006, 54, 7879– 7884, DOI: 10.1021/jf061340s
Google Scholar
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Role of Proteins in Oil-in-Water Emulsions on the Stability of Lipid Hydroperoxides
Kellerby, Sarah S.; McClements, D. Julian; Decker, Eric A.
Journal of Agricultural and Food Chemistry (2006), 54 (20), 7879-7884CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
The purpose of this research was to better understand the mechanisms by which proteins affect the rates of lipid oxidn. in order to develop protein-stabilized emulsion delivery systems with maximal oxidative stability. This study evaluated the affect of pH and emulsifier concn. on the stability of cumene hydroperoxide in hexadecane-in-water emulsions stabilized by β-lactoglobulin (β-Lg). Emulsions prepd. with 0.2 wt % β-Lg (at pH 7.0) showed a 26.9% decrease in hydroperoxide concns. 5 min after 0.25 mM ferrous ion was added to the emulsion. EDTA, but not continuous phase β-Lg, could inhibit Fe-promoted lipid hydroperoxide decompn. Lipid hydroperoxides were more stable to Fe-promoted degrdn. at pH values below the pI of β-Lg, where the emulsion droplet would be cationic and thus able to repel Fe away from the lipid hydroperoxides. Heating the β-Lg-stabilized emulsions to produce a cohesive protein layer on the emulsion droplet surface did not alter the ability of Fe to decomp. lipid hydroperoxides. These results suggest that proteins at the interface of emulsion droplets primarily stabilize lipid hydroperoxides by electrostatically inhibiting Fe-hydroperoxide interactions.
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Ćosović, B.; Vojvodić, V.; Bošković, N.; Plavšić, M.; Lee, C. Characterization of Natural and Synthetic Humic Substances (Melanoidins) by Chemical Composition and Adsorption Measurements. Org. Geochem. 2010, 41, 200– 205, DOI: 10.1016/j.orggeochem.2009.10.002
Google Scholar
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Characterization of natural and synthetic humic substances (melanoidins) by chemical composition and adsorption measurements
Cosovic, Bozena; Vojvodic, Vjerocka; Boskovic, Nikola; Plavsic, Marta; Lee, Cindy
Organic Geochemistry (2010), 41 (2), 200-205CODEN: ORGEDE; ISSN:0146-6380. (Elsevier Ltd.)
Melanoidins, condensation products of sugars and amino acids, are thought to represent a key link in the transformation of polysaccharides and proteins to humic material in the marine environment. We studied adsorption behavior of melanoidins prepd. in equimolar solns. of glucose and amino acids of choice (glutamic acid, valine and lysine) and pseudomelanoidins which were prepd. from glucose only. Melanoidins were prepd. using different condensation times (2, 4, 16 and 32 days). Synthesized melanoidins were sepd. into different mol. mass fractions. Fractionation of melanoidins by sorption on the macroreticular resin XAD-8 sepd. melanoidins into hydrophobic neutral, hydrophobic acid and hydrophilic fractions. Adsorption of melanoidins and their different fractions was studied at a Hg electrode by directly measuring the change of the double layer capacitance caused by the adsorption of org. mols. on the electrode surface through phase sensitive a.c. voltammetry. The hydrophobic acid fraction of melanoidins accounted for most of the adsorption behavior of melanoidins. Consequently, the higher mol. mass fraction of melanoidins (>10 KDa) exhibits a stronger adsorption in comparison to the lower mol. mass fraction (<3 KDa) of the same melanoidin. The good fit of adsorption data of melanoidins and pseudomelanoidins to the same adsorption isotherm supports the idea that melanoidins are comprised of a sugar derived backbone that is responsible for the adsorption behavior of melanoidin, while the presence of N atoms is responsible for the complexation of Cu ions. Adsorption characteristics and complexation ability of melanoidins and natural org. matter were similar. Our results suggest that in the process of humification, selective adsorption of condensation products on aq. surfaces may lead to a progressive immobilization of certain fractions, i.e., it is probable that higher mol. mass components accumulate at aquatic surfaces, while lower mass components remain in soln.
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Schröder, A.; Laguerre, M.; Sprakel, J.; Schroën, K.; Berton-Carabin, C. C. Pickering Particles as Interfacial Reservoirs of Antioxidants. J. Colloid Interface Sci. 2020, 575, 489– 498, DOI: 10.1016/j.jcis.2020.04.069
Google Scholar
62
Pickering particles as interfacial reservoirs of antioxidants
Schroder, Anja; Laguerre, Mickael; Sprakel, Joris; Schroen, Karin; Berton-Carabin, Claire C.
Journal of Colloid and Interface Science (2020), 575 (), 489-498CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
Emulsions are common structures encapsulating lipophilic bioactive mols., both in biol. systems and in manufd. products. Protecting these functional mols. from oxidn. is essential; Nature excels at doing so by placing antioxidants at the oil-water interface, where oxidative reactions primarily occur. We imagined a novel approach to boost the activity of antioxidants in designer emulsions by employing Pickering particles that act both as phys. emulsion stabilizers and as interfacial reservoirs of antioxidants.α-Tocopherol or carnosic acid, two model lipophilic antioxidants, were entrapped in colloidal lipid particles (CLPs) that were next used to phys. stabilize sunflower oil-in-water emulsions ("concept" Pickering emulsions). We first assessed the phys. properties and stability of the CLPs and of the Pickering emulsions. We then monitored the oxidative stability of the concept emulsions upon incubation, and compared it to that of control emulsions of similar structure, yet with the antioxidant present in the oil droplet interior. Both tested antioxidants are largely more effective when loaded within Pickering particles than when solubilized in the oil droplet interior, thus confirming the importance of the interfacial localization of antioxidants. This approach revisits the paradigm for lipid oxidn. prevention in emulsions and offers potential for many applications.
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Xu, M.; Jin, Z.; Ohm, J. B.; Schwarz, P.; Rao, J.; Chen, B. Improvement of the Antioxidative Activity of Soluble Phenolic Compounds in Chickpea by Germination. J. Agric. Food Chem. 2018, 66, 6179– 6187, DOI: 10.1021/acs.jafc.8b02208
Google Scholar
63
Improvement of the Antioxidative Activity of Soluble Phenolic Compounds in Chickpea by Germination
Xu, Minwei; Jin, Zhao; Ohm, Jae-Bom; Schwarz, Paul; Rao, Jiajia; Chen, Bingcan
Journal of Agricultural and Food Chemistry (2018), 66 (24), 6179-6187CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
Our recent study found that antioxidative activity of phenolic compds. extd. from germinated chickpea was boosted both in an in vitro assays and in oil-in-water emulsion. The purpose of this study was to elucidate the mechanism by which the compn. of phenolic compds. extd. from chickpea germination enhances its antioxidative activity. Liq. chromatog. coupled with electrospray ionization quadrupole time of flight mass spectrometry (LC-ESI-QTOF-MS) and size-exclusion chromatog. with multi-angle light-scattering and refractive index detection (SEC-MALS-RI) were employed to evaluate the phenolic compn. of sol. phenolic compds. (free and bound) and molar mass of sol. bound phenolic compds., resp., over the period of 6 days germination. According to principal component anal. of the interrelationship between germination time and phenolic compn., it is revealed that protocatechuic acid 4-O-glucoside and 6-hydroxydaidzein played a pivotal role in the sol. free phenolic compds., while gentisic acid and 7,3',4'-trihydroxyflavone were important in the sol. bound phenolic compds. Molar masses of sol. bound phenolic compds. were increased after 6 days germination. A protective and/or a dual antioxidative effects were proposed to explicate how antioxidative activity of sol. bound phenolic compds. in oil-in-water emulsions was improved with germination.
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Perron, N. R.; Brumaghim, J. L. A Review of the Antioxidant Mechanisms of Polyphenol Compounds Related to Iron Binding. Cell Biochem. Biophys. 2009, 53, 75– 100, DOI: 10.1007/s12013-009-9043-x
Google Scholar
64
A Review of the Antioxidant Mechanisms of Polyphenol Compounds Related to Iron Binding
Perron, Nathan R.; Brumaghim, Julia L.
Cell Biochemistry and Biophysics (2009), 53 (2), 75-100CODEN: CBBIFV; ISSN:1085-9195. (Springer)
A review. In this review, primary attention is given to the antioxidant (and prooxidant) activity of polyphenols arising from their interactions with iron both in vitro and in vivo. In addn., an overview of oxidative stress and the Fenton reaction is provided, as well as a discussion of the chem. of iron binding by catecholate, gallate, and semiquinone ligands along with their stability consts., UV-vis spectra, stoichiometries in soln. as a function of pH, rates of iron oxidn. by O2 upon polyphenol binding, and the published crystal structures for iron-polyphenol complexes. Radical scavenging mechanisms of polyphenols unrelated to iron binding, their interactions with copper, and the prooxidant activity of iron-polyphenol complexes are briefly discussed.
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Timoshnikov, V. A.; Kobzeva, T. v.; Polyakov, N. E.; Kontoghiorghes, G. J. Redox Interactions of Vitamin c and Iron: Inhibition of the pro-Oxidant Activity by Deferiprone. Int. J. Mol. Sci. 2020, 21, 3967, DOI: 10.3390/ijms21113967
Google Scholar
65
Redox interactions of vitamin C and iron: inhibition of the pro-oxidant activity by deferiprone
Timoshnikov, Viktor A.; Kobzeva, Tatyana V.; Polyakov, Nikolay E.; Kontoghiorghes, George J.
International Journal of Molecular Sciences (2020), 21 (11), 3967CODEN: IJMCFK; ISSN:1422-0067. (MDPI AG)
Ascorbic acid (AscH2) is one of the most important vitamins found in the human diet, with many biol. functions including antioxidant, chelating, and coenzyme activities. Ascorbic acid is also widely used in medical practice esp. for increasing iron absorption and as an adjuvant therapeutic in iron chelation therapy, but its mode of action and implications in iron metab. and toxicity are not yet clear. In this study, we used UV-Vis spectrophotometry, NMR spectroscopy, and EPR spin trapping spectroscopy to investigate the antioxidant/pro-oxidant effects of ascorbic acid in reactions involving iron and the iron chelator deferiprone (L1). The expts. were carried out in a weak acidic (pH from 3 to 5) and neutral (pH 7.4) medium. Ascorbic acid exhibits predominantly pro-oxidant activity by reducing Fe3+ to Fe2+, followed by the formation of dehydroascorbic acid. As a result, ascorbic acid accelerates the redox cycle Fe3+ ↔ Fe2+ in the Fenton reaction, which leads to a significant increase in the yield of toxic hydroxyl radicals. The anal. of the exptl. data suggests that despite a much lower stability const. of the iron-ascorbate complex compared to the FeL13 complex, ascorbic acid at high concns. is able to substitute L1 in the FeL13 chelate complex resulting in the formation of mixed L12AscFe complex. This mixed chelate complex is redox stable at neutral pH = 7.4, but decomps. at pH = 4-5 during several minutes at sub-millimolar concns. of ascorbic acid. The proposed mechanisms play a significant role in understanding the mechanism of action, pharmacol., therapeutic, and toxic effects of the interaction of ascorbic acid, iron, and L1.
66
Liang, N.; Kitts, D. D. Antioxidant Property of Coffee Components: Assessment of Methods That Define Mechanism of Action. Molecules 2014, 19, 19180– 19208, DOI: 10.3390/molecules191119180
Google Scholar
66
Antioxidant property of coffee components: assessment of methods that define mechanisms of action
Liang, Ningjian; Kitts, David D.
Molecules (2014), 19 (11), 19180-19208, 29 pp.CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)
A review. Coffee is a rich source of dietary antioxidants, and this property, coupled with the fact that coffee is one of the world' s most popular beverages, has led to the understanding that coffee is a major contributor to dietary antioxidant intake. Brewed coffee is a complex food matrix with numerous phytochem. components that have antioxidant activity capable of scavenging free radicals, donating hydrogen and electrons, providing reducing activity and also acting as metal ion pro-oxidant chelators. More recent studies have shown that coffee components can trigger tissue antioxidant gene expression and protect against gastrointestinal oxidative stress. This paper will describe different in vitro, cell-free and cell-based assays that both characterize and compare the antioxidant capacity and mechanism of action of coffee and its bioactive constituents. Moreover, evidence of cellular antioxidant activity and correlated specific genomic events induced by coffee components, which are relevant to antioxidant function in both animal and human studies, will be discussed.
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Hwang, H. S.; Winkler-Moser, J. K.; Kim, Y.; Liu, S. X. Antioxidant Activity of Spent Coffee Ground Extracts Toward Soybean Oil and Fish Oil. Eur. J. Lipid Sci. Technol. 2019, 121, 1800372, DOI: 10.1002/ejlt.201800372
Google Scholar
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Abstract
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Figure 1
Figure 1. Surface pressure of WPI and coffee fractions (0.01 w/v % in water) as a function of time, at the stripped oil–water interface, at 20 °C. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates.
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Figure 2
Figure 2. Droplet size distribution of emulsions stabilized with WPI (A), coffee brew (B), HMWF (C), and non-defatted HMWF (D) freshly prepared (solid line) or after 7 days at 40 °C (2) (dotted line). For all emulsions, the concentration of the emulsifying ingredient was 2 wt %. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates.
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Figure 3
Figure 3. Microscopic pictures of emulsions stabilized with WPI (A), coffee brew (B), HMWF (C), and non-defatted HMWF (D) freshly prepared (1) or after 7 days at 40 °C (2).
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Figure 4
Figure 4. Zeta-potential of the emulsions freshly prepared or after 7 days at 40 °C. The lowercase letter is for comparison among different emulsions. Different letters indicate significant differences (P < 0.05). Asterisks indicate a significant difference for the same sample between day 0 and day 7.
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Figure 5
Figure 5. DPPH radical scavenging activity (A) and iron-chelating capacity (B) of WPI and different coffee fractions. The lowercase letter is for comparison among the samples. Different letters indicate significant differences (P < 0.05).
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Figure 6
Figure 6. Hydroperoxide concentrations (left column) and para-anisidine values (right column) in different emulsions over the incubation period (40 °C, 7 days). Top row: all emulsions; bottom row: coffee fraction-stabilized emulsions (bottom row graphs show a magnification on low values of oxidation markers; please note the difference in Y-axis scales between panels A/a and panels B/b).
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Figure 7
Figure 7. Droplet size distribution of WPI-stabilized emulsions stabilized with 0 (A), 0.125 (B), 0.25 (C), 0.5 (D), 1 (E), and 2 (F) w/v % HMW coffee melanoidins added to the emulsion post-homogenization. For clarity, one representative curve is shown for each sample, but similar results were obtained on independent triplicates. The red curve in (A) is corresponding to the particle size distribution of the HMWF dispersion.
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Figure 8
Figure 8. Zeta-potential of the WPI-stabilized emulsions supplemented with 0–2 w/v % of HMWF freshly prepared or at the end of the incubation period (40 °C, 4 days).
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Figure 9
Figure 9. Hydroperoxide concentrations (A) and para-anisidine values (B) in WPI-stabilized emulsions supplemented with 0 to 2 w/v % of HMWF, over the incubation period (40 °C, 4 days).
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Figure 10
Figure 10. Hydroperoxide concentrations (A) and para-anisidine values (B) in WPI-stabilized emulsions supplemented with excess WPI or various coffee fractions (0.25 wt %) over the incubation period (40 °C, 4 days).
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References
This article references 67 other publications.
1. 1
  Morzelle, M. C.; Watkins, B. A.; Li, Y.; Hennig, B.; Toborek, M. Dietary Lipids and Health. Bailey’s Industrial Oil and Fat Products; John Wiley & Sons, 2020; pp 1– 27.
  There is no corresponding record for this reference.
2. 2
  McClements, D. J.; Decker, E. Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation. J. Agric. Food Chem. 2018, 66, 20– 35, DOI: 10.1021/acs.jafc.7b05066
  2
  Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation
  McClements, David Julian; Decker, Eric
  Journal of Agricultural and Food Chemistry (2018), 66 (1), 20-35CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  A review. There has been strong interest in developing effective strategies to inhibit lipid oxidn. in emulsified food products due to the need to incorporate oxidatively labile bioactive lipids, such as w-3 fatty acids, conjugated linoleic acids, or carotenoids. Emulsifiers or co-emulsifiers can be utilized to inhibit lipid oxidn. in emulsions. Both of these mol. types can adsorb to droplet surfaces and inhibit lipid oxidn., but emulsifiers can also stabilize droplets against aggregation whereas co-emulsifiers cannot. There are a host of existing emulsifiers, covalent conjugates, or phys. complexes that have the potential to inhibit lipid oxidn. by a variety of mechanisms. Existing emulsifiers with antioxidant potential consist of surfactants, phospholipids, proteins, polysaccharides and colloidal particles. Conjugates and complexes are typically formed by covalently or phys. linking together a surface-active mol. with an antioxidant mol. This article, reviews the mol. and physicochem. basis for the surface and antioxidant activities of emulsifiers and co-emulsifiers, highlights the important properties of interfacial layers that can be engineered to control lipid oxidn., and outlines different kinds of existing emulsifiers, conjugates, and complexes that can be used to inhibit oxidn.
3. 3
  Villière, A.; Rousseau, F.; Brossard, C.; Genot, C. Sensory Evaluation of the Odour of a Sunflower Oil Emulsion throughout Oxidation. Eur. J. Lipid Sci. Technol. 2007, 109, 38– 48, DOI: 10.1002/ejlt.200600084
  3
  Sensory evaluation of the odour of a sunflower oil emulsion throughout oxidation
  Villiere, Angelique; Rousseau, Florence; Brossard, Chantal; Genot, Claude
  European Journal of Lipid Science and Technology (2007), 109 (1), 38-48CODEN: EJLTFM; ISSN:1438-7697. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Oxidn. of unsatd. fatty acids is responsible for off-flavours, often described as rancid flavours. This study was aimed at describing the evolution of the odor of a sunflower oil-in-water emulsion during oxidn. at 50 °C in the dark. Appearance of an odor and occurrence of oxidn. were first tested for at short-time aging (0-4 h) by the triangle test and measurements of oxygen consumption, resp. The odor of the emulsion oxidised for up to 240 h was then characterised by sensory profile, while volatiles issued from lipid oxidn. were analyzed in the headspace by SPME. From 1 h of aging, while oxygen consumption remained weak, a significant change of the odor was detected by the panel. Up to 21 volatile compds. were identified in the headspace of long-time-oxidised emulsions. Beyond the rancid attribute, seven attributes were chosen to describe the odor of oxidised emulsions, four of which referring to solns. of a single volatile oxidn. compd. The contribution of the fresh oil attribute, initially dominant, was progressively overtaken from 6 to 24 h of aging by the deep-fried attribute, which later declined in favor of the painty attribute, predominant after 100 h. Evolution of intensity scores and contribution to odor profiles of attributes could not be easily related to one ref. volatile compd. or another, confirming the complex relationship between the generated volatile compds. and the perceived odor.
4. 4
  Rasheed, A.; Fathima Abdul Azeez, R. A Review on Natural Antioxidants. In Traditional and Complementary Medicine; IntechOpen, 2019.
  There is no corresponding record for this reference.
5. 5
  Parliment, T. H. An Overview of Coffee Roasting. ACS Symp. Ser. 2000, 754, 188– 201, DOI: 10.1021/bk-2000-0754.ch020
  5
  An overview of coffee roasting
  Parliment, Thomas H.
  ACS Symposium Series (2000), 754 (Caffeinated Beverages), 188-201CODEN: ACSMC8; ISSN:0097-6156. (American Chemical Society)
  A review with 25 refs. The coffee beverage as presently consumed is an aq. ext. of the roasted and ground seed of the fruit of the coffee plant. It is consumed for its pleasant flavor and aroma and its stimulatory properties due to caffeine. The flavor of roasted coffee is quite complex; chem. and flavor changes occur when the bean is roasted and nearly 800 aroma compds. are generated.
6. 6
  Panusa, A.; Zuorro, A.; Lavecchia, R.; Marrosu, G.; Petrucci, R. Recovery of Natural Antioxidants from Spent Coffee Grounds. J. Agric. Food Chem. 2013, 61, 4162– 4168, DOI: 10.1021/jf4005719
  6
  Recovery of natural antioxidants from spent coffee grounds
  Panusa, Alessia; Zuorro, Antonio; Lavecchia, Roberto; Marrosu, Giancarlo; Petrucci, Rita
  Journal of Agricultural and Food Chemistry (2013), 61 (17), 4162-4168CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Spent coffee grounds (SCG) were extd. with an environmentally friendly procedure and analyzed to evaluate the recovery of relevant natural antioxidants for use as nutritional supplements, foods, or cosmetic additives. SCG were characterized in terms of their total phenolic content by the Folin-Ciocalteu procedure and antioxidant activity by the DPPH scavenging assay. Flavonoid content was also detd. by a colorimetric assay. The total phenolic content was strongly correlated with the DPPH scavenging activity, suggesting that phenolic compds. are mainly responsible for the antioxidant activity of SCG. An UHPLC-PDA-TOF-MS system was used to sep., identify, and quantify phenolic and nonphenolic compds. in the SCG exts. Important amts. of chlorogenic acids (CGA) and related compds. as well as caffeine (CAF) evidenced the high potential of SCG, a waste material that is widely available in the world, as a source of natural phenolic antioxidants.
7. 7
  Del Pino-García, R.; González-SanJosé, M. L.; Rivero-Pérez, M. D.; Muñiz, P. Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee: Contribution of the Melanoidin Fraction. J. Agric. Food Chem. 2012, 60, 10530– 10539, DOI: 10.1021/jf302747v
  7
  Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee: Contribution of the Melanoidin Fraction
  Del Pino-Garcia, Raquel; Gonzalez-SanJose, Maria L.; Rivero-Perez, Maria D.; Muniz, Pilar
  Journal of Agricultural and Food Chemistry (2012), 60 (42), 10530-10539CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The roasting process induces chem. changes in coffee beans that strongly affect the antioxidant activity of coffee. The polyphenol and melanoidin contents and the antioxidant activity of three instant coffees with different roasting degrees (light, medium, and dark) were assessed. Coffee brews were sepd. into fractions, and the potential biol. activity of the melanoidins was evaluated by simulating their gastrointestinal digestion. Total antioxidant capacity, hydroxyl radical scavenger activity, lipid peroxidn. inhibition capacity, and protection against DNA oxidative damage (in vitro and ex vivo genoprotective effects) were detd. Instant coffee has a high total antioxidant capacity and protective effect against certain oxidative stress biomarkers (lipids and DNA), although this capacity decreases with the roasting degree. This confirms the hypothesis that several of the polyphenols present in coffee may become part of the melanoidins generated during roasting. Furthermore, the elevated genoprotective effect of melanoidin-digested fractions is noteworthy.
8. 8
  Delgado-Andrade, C.; Morales, F. J. Unraveling the Contribution of Melanoidins to the Antioxidant Activity of Coffee Brews. J. Agric. Food Chem. 2005, 53, 1403– 1407, DOI: 10.1021/jf048500p
  8
  Unraveling the contribution of melanoidins to the antioxidant activity of coffee brews
  Delgado-Andrade, Cristina; Morales, Francisco J.
  Journal of Agricultural and Food Chemistry (2005), 53 (5), 1403-1407CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Instant coffees produced from the same green coffee beans were supplied from a company in different roasting degrees, light, medium, and dark. Melanoidins were obtained by ultrafiltration (10 kDa) and subsequent diafiltration. Pure melanoidins were isolated from melanoidins after overnight incubation in 2 M NaCl. The antioxidant activities of instant coffees, melanoidins, and pure melanoidins were tested using the conjugated diene formation from a 2,2'-azobis(2-amidinopropane) dihydrochloride-induced linoleic acid oxidn. in an aq. system. No significant differences were found between melanoidins and pure melanoidins with different roasting degrees. Therefore, the contribution of the pure melanoidin fraction to the total antioxidant activity of melanoidins was significantly lower. More than 50% of the antioxidant activity of melanoidins is due to low mol. wt. compds. linked non-covalently to the melanoidin skeleton. A new concept of the overall antioxidant properties of food melanoidins is described, where chelating ability toward low mol. wt. antioxidant compds. is connected to the stabilization of these compds. involved in the shelf life of the product.
9. 9
  ALjahdali, N.; Carbonero, F. Impact of Maillard Reaction Products on Nutrition and Health : Current Knowledge and Need to Understand Their Fate in the Human Digestive System. Crit. Rev. Food Sci. Nutr. 2019, 59, 474– 487, DOI: 10.1080/10408398.2017.1378865
  9
  Impact of Maillard reaction products on nutrition and health: Current knowledge and need to understand their fate in the human digestive system
  Aljahdali, Nesreen; Carbonero, Franck
  Critical Reviews in Food Science and Nutrition (2019), 59 (3), 474-487CODEN: CRFND6; ISSN:1040-8398. (Taylor & Francis, Inc.)
  The Maillard Reaction (MR) is a non-enzymic chem. reaction which results in the linkage between the amino group of amino acids and the carbonyl group of reduced sugars. MR products (MRPs) are common components of processed foods, mainly as a result of heating, esp. in the Western diet. MRPs are classified as into three stages: initial, intermediate, and final stages, indicative of increased complexity and size, incurring different flavor, aroma, and texture. MRPs presence is known to reduce the nutritional quality of foods, particularly by reducing protein digestibility. Early reports have linked MRPs, esp. advanced glycation end-products (AGEs) present in high concn. in the typical Western diet, to health conditions and diseases. However conflicting data has since been reported, and only a few (acrylamide, heterocyclic amines and 5-Hydroxymethylfurfural) MRPs have documented potential toxic or carcinogenic effects. High mol. wt. MRPs are not available for direct absorption in the higher gastrointestinal tract, and are thus mostly metabolized by resident colonic microbes. MRPs have been the subject of sparse research interest in comparison with other non-digestible dietary elements. In this review, we outline the state of knowledge on MRPs in nutrition and health, and highlight the need to develop the limited knowledge on their impact on the gut microbiota and which metabolites derive from MRPs fermn.
10. 10
  Delgado-andrade, C.; Fogliano, V. Dietary Advanced Glycosylation End-Products (DAGEs) and Melanoidins Formed through the Maillard Reaction: Physiological Consequences of Their Intake. Annu. Rev. Food Sci. Technol. 2018, 9, 271, DOI: 10.1146/annurev-food-030117-012441
  10
  Dietary Advanced Glycosylation End-Products (dAGEs) and Melanoidins Formed through the Maillard Reaction: Physiological Consequences of their Intake
  Delgado-Andrade, Cristina; Fogliano, Vincenzo
  Annual Review of Food Science and Technology (2018), 9 (), 271-291CODEN: ARFSBV; ISSN:1941-1413. (Annual Reviews)
  The main purpose of this review is to clarify whether the consumption of food rich in melanoidins and dietary advanced glycosylation end-products (dAGEs) is harmful or beneficial for human health. There are conflicting results on their harmful effects in the literature, partly due to a methodol. issue in how dAGEs are detd. in food. Melanoidins have pos. functions particularly within the gastrointestinal tract, whereas the intake of dAGEs has controversial physiol. consequences. Most of the in vivo intervention trials were done comparing boiled vs. roasted diet (low and high dAGE, resp.). However, these studies can be biased by different lipid oxidn. and by different calorie d. of foods in the two conditions. The attraction that humans have to cooked foods is linked to the benefits they have had during mankind's evolution. The goal for food technologists is to design low-energy-dense products that can satisfy humans' attraction to rewarding cooked foods.
11. 11
  Yanagimoto, K.; Ochi, H.; Lee, K. G.; Shibamoto, T. Antioxidative Activities of Fractions Obtained from Brewed Coffee. J. Agric. Food Chem. 2004, 52, 592– 596, DOI: 10.1021/jf030317t
  11
  Antioxidative Activities of Fractions Obtained from Brewed Coffee
  Yanagimoto, Kenichi; Ochi, Hirotomo; Lee, Kwang-Geun; Shibamoto, Takayuki
  Journal of Agricultural and Food Chemistry (2004), 52 (3), 592-596CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The antioxidative activity of column chromatog. fractions obtained from brewed coffee was investigated to find antioxidants and to assess the benefit of coffee drinking. The dichloromethane ext. inhibited hexanal oxidn. by 100 and 50% for 15 days and 30 days, resp., at the level of 5 μg/mL. A GC/MS anal. of fractions, which exhibited oxidative activity, revealed the presence of antioxidative heterocyclic compds. including furans, pyrroles, and maltol. The residual aq. soln. exhibited slight antioxidative activity. The inhibitory activity of the 7 fractions from an aq. soln. toward malonaldehyde formation from lipid oxidn. ranged from 10 to 90 at a level of 300 μg/mL. Thus, brewed coffee contains many antioxidants and consumption of antioxidant-rich brewed coffee may inhibit diseases caused by oxidative damages.
12. 12
  Delgado-Andrade, C.; Rufián-Henares, J. A.; Morales, F. J. Assessing the Antioxidant Activity of Melanoidins from Coffee Brews by Different Antioxidant Methods. J. Agric. Food Chem. 2005, 53, 7832– 7836, DOI: 10.1021/jf0512353
  12
  Assessing the Antioxidant Activity of Melanoidins from Coffee Brews by Different Antioxidant Methods
  Delgado-Andrade, Cristina; Rufian-Henares, Jose A.; Morales, Francisco J.
  Journal of Agricultural and Food Chemistry (2005), 53 (20), 7832-7836CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Antioxidant activity of instant coffees produced from the same green coffee beans roasted at three different degrees was analyzed. Coffee melanoidins were obtained by ultrafiltration (10 kDa cutoff) and subsequent diafiltration. Pure melanoidins were isolated from melanoidins after overnight incubation in 2 M NaCl and then ultrafiltered. Filtrates, corresponding to the low mol. wt. (LMW) fraction noncovalently linked to the melanoidin skeleton, were also preserved. Antioxidant activity of coffee brews (CB), melanoidins (M), pure melanoidins (PM), and bound melanoidin compds. (BMC) were tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing power (FRAP) methods. The higher contribution of melanoidins to the total antioxidant activity of coffees was shown to be caused by the LMW compds. linked noncovalently to the melanoidin skeleton, as data from BMC confirmed. CB, M, and BMC fractions exert the highest antioxidant activity in aq. media, whereas PM was not dependent on the reaction media. The highest correlation was found between DPPH and FRAP methods.
13. 13
  Mesías, M.; Delgado-Andrade, C. Melanoidins as a Potential Functional Food Ingredient. Curr. Opin. Food Sci. 2017, 14, 37– 42, DOI: 10.1016/j.cofs.2017.01.007
  There is no corresponding record for this reference.
14. 14
  Echavarría, A. P.; Pagán, J.; Ibarz, A. Melanoidins Formed by Maillard Reaction in Food and Their Biological Activity. Food Eng. Rev. 2012, 4, 203– 223, DOI: 10.1007/s12393-012-9057-9
  14
  Melanoidins formed by Maillard reaction in food and their biological activity
  Echavarria, A. P.; Pagan, J.; Ibarz, A.
  Food Engineering Reviews (2012), 4 (4), 203-223CODEN: FEROB9; ISSN:1866-7910. (Springer)
  This paper is a review of the recent studies on Maillard reaction products, the formation mechanism for these compds. and melanoidin structure, the undesirable consequences in food esp. in fruit juice processing, the desirable effects and the biol. properties related to health benefits. Melanoidins are compds. generated in the late stages of the Maillard reaction from reducing sugars and proteins or amino acids during food processing and preservation. Recently, the effects of melanoidins on human health and the chem. characterization of the beneficial components have gained a lot of attention, and their implications on several levels, sensory, nutritional, toxicol. and technol. were investigated. Food melanoidins have been reported to be anionic, colored compds., and some of their key chromophores have been elucidated. The antioxidant activity and other biol. effects of melanoidins from real foods and model systems have been widely studied. Despite this, very few different melanoidin structures have actually been described, and specific health effects have yet to be linked with chem. distinct melanoidins. The variety of Maillard reaction products formed during the reaction, in conjunction with the difficulty in purifying and identifying them, makes a thorough anal. of melanoidins challenging.
15. 15
  Moreira, A. S. P.; Nunes, F. M.; Domingues, M. R.; Coimbra, M. A. Coffee Melanoidins: Structures, Mechanisms of Formation and Potential Health Impacts. Food Funct. 2012, 3, 903– 915, DOI: 10.1039/c2fo30048f
  15
  Coffee melanoidins: structures, mechanisms of formation and potential health impacts
  Moreira, Ana S. P.; Nunes, Fernando M.; Domingues, M. Rosario; Coimbra, Manuel A.
  Food & Function (2012), 3 (9), 903-915CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
  A review. During the roasting process, coffee bean components undergo structural changes leading to the formation of melanoidins, which are defined as high mol. wt. nitrogenous and brown-colored compds. As coffee brew is one of the main sources of melanoidins in the human diet, their health implications are of great interest. In fact, several biol. activities, such as antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative activities, have been attributed to coffee melanoidins. To understand the potential of coffee melanoidin health benefits, it is essential to know their chem. structures. The studies undertaken to date dealing with the structural characterization of coffee melanoidins have shown that polysaccharides, proteins, and chlorogenic acids are involved in coffee melanoidin formation. However, exact structures of coffee melanoidins and mechanisms involved in their formation are far from being elucidated. This paper systematizes the available information and provides a crit. overview of the knowledge obtained so far about the structure of coffee melanoidins, mechanisms of their formation, and their potential health implications.
16. 16
  Coelho, C.; Ribeiro, M.; Cruz, A. C. S.; Domingues, M. R. M.; Coimbra, M. A.; Bunzel, M.; Nunes, F. M. Nature of Phenolic Compounds in Coffee Melanoidins. J. Agric. Food Chem. 2014, 62, 7843– 7853, DOI: 10.1021/jf501510d
  16
  Nature of Phenolic Compounds in Coffee Melanoidins
  Coelho, Carina; Ribeiro, Miguel; Cruz, Ana C. S.; Domingues, M. Rosario M.; Coimbra, Manuel A.; Bunzel, Mirko; Nunes, Fernando M.
  Journal of Agricultural and Food Chemistry (2014), 62 (31), 7843-7853CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Phenolic compds. are incorporated into coffee melanoidins during roasting mainly in condensed form (42-62 mmol/100 g) and also in ester-linked form (1.1-1.6 mmol/100 g), with incorporation levels depending on the green coffee chlorogenic acid content. The phenolic compds. are incorporated in different coffee melanoidin populations, but mainly in those sol. in 75% ethanol (82%), a significant correlation between the amt. of phenolic compds. and the amt. of protein and color characteristics of the different melanoidin populations being obsd. The incorporation of phenolic compds. into coffee melanoidins is a significant pathway of chlorogenic acid degrdn. during roasting, representing 23% of the chlorogenic acids lost. These account for the nearly 26% of the material not accounted for by polysaccharides and proteins present in coffee melanodins. The cleavage mechanism and the efficiency of alk. fusion used to release condensed phenolics from coffee melanoidins suggest that the phenolic compds. can be linked to the polymeric material by aryl-ether, stilbene type, and/or biphenyl linkages.
17. 17
  Verzelloni, E.; Tagliazucchi, D.; Del Rio, D.; Calani, L.; Conte, A. Antiglycative and Antioxidative Properties of Coffee Fractions. Food Chem. 2011, 124, 1430– 1435, DOI: 10.1016/j.foodchem.2010.07.103
  There is no corresponding record for this reference.
18. 18
  Perrone, D.; Farah, A.; Donangelo, C. M. Influence of Coffee Roasting on the Incorporation of Phenolic Compounds into Melanoidins and Their Relationship with Antioxidant Activity of the Brew. J. Agric. Food Chem. 2012, 60, 4265– 4275, DOI: 10.1021/jf205388x
  18
  Influence of Coffee Roasting on the Incorporation of Phenolic Compounds into Melanoidins and Their Relationship with Antioxidant Activity of the Brew
  Perrone, Daniel; Farah, Adriana; Donangelo, Carmen M.
  Journal of Agricultural and Food Chemistry (2012), 60 (17), 4265-4275CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  In the present study, the influence of coffee roasting on free and melanoidin-bound phenolic compds. and their relationship with the brews' antioxidant activity (AA), evaluated by TRAP, TEAC, and TRAP, were investigated. Changes in the relative content of free chlorogenic acids (CGA), free lactones, and melanoidin-bound phenolic acids during roasting indicate that phenolic compds. were incorporated into melanoidins mainly at early stages of the process, being thereafter partly oxidized to dihydrocaffeic acid, and degraded. Although less than 1% of CGA in green coffee was incorporated into melanoidins during roasting, the relative content of melanoidin-bound phenolic acids increased significantly during this process, reaching up to 29% of total phenolic compds. in brews from dark roasted coffees. Regardless of the AA assay used and considering all roasting degrees, the overall contribution of CGA to the AA of the whole brews was higher than that of melanoidin-bound phenolic compds. It was estd. that the latter compds. contributed to 25-47% of the AA, depending on the assay used.
19. 19
  Decker, E. A.; McClements, D. J.; Bourlieu-Lacanal, C.; Durand, E.; Figueroa-Espinoza, M. C.; Lecomte, J.; Villeneuve, P. Hurdles in Predicting Antioxidant Efficacy in Oil-in-Water Emulsions. Trends Food Sci. Technol. 2017, 67, 183– 194, DOI: 10.1016/j.tifs.2017.07.001
  19
  Hurdles in Predicting Antioxidant Efficacy in Oil-in-water emulsions
  Decker, Eric A.; McClements, D. Julian; Bourlieu-Lacanal, Claire; Durand, Erwann; Figueroa-Espinoza, Maria Cruz; Lecomte, Jerome; Villeneuve, Pierre
  Trends in Food Science & Technology (2017), 67 (), 183-194CODEN: TFTEEH; ISSN:0924-2244. (Elsevier Ltd.)
  A review. Numerous compds. exist in nature that can scavenge free radicals and thus have the potential to act as antioxidants in foods. Interest in natural free radical scavengers has resulted in tens of thousands of publications on various mols. and exts. but only an extremely small no. have actually been used in com. applications. The gap between research interest and com. application is mainly due to the lack of bench top methods that can predict the efficacy of antioxidants in complex food matrixes. This disconnection seems to be due to the extremely complex nature of lipid oxidn. and antioxidant activity in even relatively simple food systems such as oil-in-water emulsions. This review highlights a no. of areas where lack of knowledge is currently holding back our ability to predict which free radical scavengers will be good antioxidants in emulsions: non-free radical scavenging reactions of antioxidants; the existence of different types of oil-water interfaces; difficulties in characterizing lipid droplet surfaces; and differences in oxidn. kinetics in different lipid droplets. Further research is needed to identify the key factors that det. antioxidant efficacy in complex heterogeneous systems. This knowledge would then increase our ability to predict how antioxidant structure and properties relate to their activity in food emulsions.
20. 20
  Berton-Carabin, C. C.; Ropers, M. H.; Genot, C. Lipid Oxidation in Oil-in-Water Emulsions: Involvement of the Interfacial Layer. Compr. Rev. Food Sci. Food Saf. 2014, 13, 945– 977, DOI: 10.1111/1541-4337.12097
  20
  Lipid oxidation in oil-in-water emulsions: involvement of the interfacial layer
  Berton-Carabin, Claire C.; Ropers, Marie-Helene; Genot, Claude
  Comprehensive Reviews in Food Science and Food Safety (2014), 13 (5), 945-977CODEN: CRFSBJ; ISSN:1541-4337. (Institute of Food Technologists)
  A review. More polyunsatd. fats in processed foods and fewer additives are a huge demand of public health agencies and consumers. Consequently, although foods have an enhanced tendency to oxidize, the usage of antioxidants, esp. synthetic antioxidants, is restrained. An alternate soln. is to better control the localization of reactants inside the food matrix to limit oxidn. This review establishes the state-of-the-art on lipid oxidn. in oil-in-water (O/W) emulsions, with an emphasis on the role of the interfacial region, a crit. area in the system in that respect. We first provide a summary on the essential basic knowledge regarding (i) the structure of O/W emulsions and interfaces and (ii) the general mechanisms of lipid oxidn. Then, we discuss the factors involved in the development of lipid oxidn. in O/W emulsions with a special focus on the role played by the interfacial region. The multiple effects that can be attributed to emulsifiers according to their chem. structure and their location, and the interrelationships between the parameters that define the physicochem. and structure of emulsions are highlighted. This work sheds new light on the interpretation of reported results that are sometimes ambiguous or contradictory.
21. 21
  Feng, J.; Berton-Carabin, C. C.; Guyot, S.; Gacel, A.; Fogliano, V.; Schroën, K. Coffee Melanoidins as Emulsion Stabilizers. Food Hydrocolloids 2023, 139, 108522, DOI: 10.1016/j.foodhyd.2023.108522
  21
  Coffee melanoidins as emulsion stabilizers
  Feng, Jilu; Berton-Carabin, Claire C.; Guyot, Sylvain; Gacel, Agnes; Fogliano, Vincenzo; Schroen, Karin
  Food Hydrocolloids (2023), 139 (), 108522CODEN: FOHYES; ISSN:0268-005X. (Elsevier Ltd.)
  The use of conventional food stabilizers (e.g., surfactants and animal-derived proteins) is not in line with consumer demands for natural products. This has led to a great interest in novel emulsion stabilizers. In this paper, we explore the emulsification properties of coffee melanoidins, which are brown polymers made up by polysaccharides, proteins and polyphenols formed during bean roasting. The phys. properties and stability of oil-in-water (O/W) emulsions (10 wt% oil) stabilized with 0.25-4 wt% coffee melanoidins were investigated upon storage. Coffee melanoidins can form emulsions with a nearly monomodal size distribution. Upon 28 days of storage at room temp., emulsions prepd. with low (0.25-1 wt%) melanoidin concns. underwent creaming, flocculation, and coalescence; emulsions prepd. with high (4 wt%) melanoidin concns. gradually transformed from a liq.-like state to a gel-like structure, and emulsions prepd. with 2 wt% melanoidins were phys. stable. Stabilization of the emulsions is explained by both interfacial effects and an increased viscosity at high melanoidin concns. Surface load detn., confocal laser scanning microscopy (CLSM), and polarized light microscopy revealed that polysaccharide-rich melanoidins were able to adsorb at the droplet surface. We conclude that coffee melanoidins act both as emulsifiers (decreasing the interfacial tension and inducing electrostatic and steric repulsion) and texture modifiers (increasing the viscosity of emulsions). Coffee melanoidins can be used as natural emulsifiers in targeted food products.
22. 22
  Berton, C.; Genot, C.; Ropers, M. Quantification of Unadsorbed Protein and Surfactant Emulsifiers in Oil-in-Water Emulsions. J. Colloid Interface Sci. 2011, 354, 739– 748, DOI: 10.1016/j.jcis.2010.11.055
  22
  Quantification of unadsorbed protein and surfactant emulsifiers in oil-in-water emulsions
  Berton, Claire; Genot, Claude; Ropers, Marie-Helene
  Journal of Colloid and Interface Science (2011), 354 (2), 739-748CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
  Unadsorbed emulsifiers affect the phys. and chem. behavior of oil-in-water (O/W) emulsions. A simple methodol. to quantify unadsorbed emulsifiers in the aq. phase of O/W emulsions was developed. Emulsions were centrifuged and filtered to sep. the aq. phase from the oil droplets and the concn. of unadsorbed emulsifiers in the aq. phase detd. The quantification of unadsorbed surfactants based on the direct transesterification of their fatty acids was validated for Tween 20, Tween 80, citric acid ester (Citrem), Span 20 and monolauroyl glycerol. To det. unadsorbed proteins, results obtained with Folin-Ciocalteu reagent or UV-spectrophotometry were compared on emulsions stabilized by β-lactoglobulin (BLG), β-casein (BCN) or bovine serum albumin (BSA). The 1st method gave more accurate results esp. during aging of emulsions in oxidative conditions. The whole methodol. was applied to emulsions stabilized with single or mixed emulsifiers. This approach enables optimization of emulsion formulations and could be useful to follow changes in the levels of unadsorbed emulsifiers during phys. or chem. aging processes.
23. 23
  Nielsen, S. S. Phenol-Sulfuric Acid Method for Total Carbohydrates. In Food Analysis Laboratory Manual; Nielsen, S. S., Ed.; Springer US: Boston, MA, 2010, pp 47– 53.
  There is no corresponding record for this reference.
24. 24
  Bekedam, E. K.; Schols, H. A.; van Boekel, M. A. J. S.; Smit, G. High Molecular Weight Melanoidins from Coffee Brew. J. Agric. Food Chem. 2006, 54, 7658– 7666, DOI: 10.1021/jf0615449
  24
  High Molecular Weight Melanoidins from Coffee Brew
  Bekedam, E. Koen; Schols, Henk A.; van Boekel, Martinus A. J. S.; Smit, Gerrit
  Journal of Agricultural and Food Chemistry (2006), 54 (20), 7658-7666CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The compn. of high mol. wt. (HMw) coffee melanoidin populations, obtained after ethanol pptn., was studied. The specific extinction coeff. (Kmix) at 280, 325, 405 nm, sugar compn., phenolic group content, nitrogen content, amino acid compn., and non-protein nitrogen (NPN) content were investigated. Results show that most HMw coffee melanoidins are sol. at high ethanol concns. The amino acid compn. of the HMw fractions was similar, while 17% (wt./wt.) of the nitrogen was NPN, probably originating from degraded amino acids/proteins and now part of melanoidins. A strong correlation between the melanoidin content, the NPN, and protein content was found. It was concluded that proteins are incorporated into the melanoidins and that the degree of chem. modification, for example, by phenolic groups, dets. the soly. of melanoidins in ethanol. Although the existence of covalent interaction between melanoidins and polysaccharides were not proven in this study, the findings suggest that esp. arabinogalactan is likely involved in melanoidin formation. Finally, phenolic groups were present in the HMw fraction of coffee, and a correlation was found with the melanoidin concn.
25. 25
  Singleton, V. L.; Rossi, J. A. Colorimetry of Total Phenolics With Phosphomolybdic-Phosphotungstic Acid Reagents. Am. J. Enol. Vitic. 1965, 16, 144– 158
  25
  Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid reagents
  Singleton, V. L.; Rossi, Joseph A., Jr.
  American Journal of Enology and Viticulture (1965), 16 (3), 144-58CODEN: AJEVAC; ISSN:0002-9254.
  The spectral properties, typical molar absorptivities with known compds., and various procedural variables of importance in detg. phenolic substances in natural products by means of Folin-Denis type reagents were investigated. The Folin-Ciocalteu form of the reagent is preferred over the Folin-Denis form previously recommended for "tannin" detn. in wines and spirits. Anhyd. gallic acid is recommended as the reference standard instead of tannic acid. Time, temp., and alkali concn. to give max. color development and avoid appreciable fading were studied. Numerically comparable results, a least equiv. accuracy, and considerably improved reproducibility were shown if the procedure was modified to the following form. Samples (1.00 ml. of white wine or a 1/10 diln. of red wine) are mixed with at least 60 ml. of distd. H2O in a 100-ml. volumetric flask. Five ml. Folin-Ciocalteu reagent is added and mixed, and after about 30 sec. and before 8 min. 3.0 g. of anhyd. Na2CO3 in aq. soln. (e.g. 15 ml. of 200 g./l.) is added, mixed, and the contents of the flask dild. to vol. After 2 hrs. at 75°F. the absorbance at 765 mμ is detd. in comparison with a similarly prepd. set of gallic acid standards of about 0-500 γ/flask. A procedure scaled down to a final vol. of 20.00 ml. is also given.
26. 26
  Zhang, H.; Zhang, H.; Troise, A. D.; Fogliano, V. Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions. J. Agric. Food Chem. 2019, 67, 10921– 10929, DOI: 10.1021/acs.jafc.9b03744
  26
  Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions
  Zhang, Hao; Zhang, Hui; Troise, Antonio Dario; Fogliano, Vincenzo
  Journal of Agricultural and Food Chemistry (2019), 67 (39), 10921-10929CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Free amino residues react with α-dicarbonyl compds. (DCs) contributing to the formation of advanced glycation end-products (AGEs). Phenolic compds. can scavenge DCs thus controlling dietary carbonyl load. This study showed that high mol. wt. cocoa (HMW-COM), bread (HMW-BM) and esp. coffee (HMW-CM) melanoidins are effective DCs scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiol. conditions, suggesting some physiol. relevance. Partial acid hydrolysis of HMW-CM decreased dicarbonyl trapping capacity demonstrating that the ability to react with glyoxal, methylglyoxal and diacetyl was mainly due to polyphenols bound to macromols. Caffeic acid and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and arom. substitution reactions led to the formation of a stable adduct between caffeic acid and methylglyoxal. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGEs formation across the gastrointestinal tract.
27. 27
  Yen, G.-C.; Hsieh, P.-P. Antioxidative Activity and Scavenging Effects on Active Oxygen of Xylose-lysine Maillard Reaction Products. J. Sci. Food Agric. 1995, 67, 415– 420, DOI: 10.1002/jsfa.2740670320
  27
  Antioxidative activity and scavenging effects on active oxygen of xylose-lysine maillard reaction products
  Yen, Gow-Chin; Hsieh, Ping-Ping
  Journal of the Science of Food and Agriculture (1995), 67 (3), 415-20CODEN: JSFAAE; ISSN:0022-5142. (Wiley)
  The antioxidative activity and scavenging effects on active oxygen of Maillard reaction products (MRP) prepd. by heating xylose and lysine (XL) at a molar ratio 1:2 and pH 9.0 for 1-5 h (XL-1 to XL-5) were investigated. The antioxidative activity and browning intensity of XL MRP increased with increasing duration of reaction, but XL-1 and XL-2 MRP showed greater reducing power than other samples. All XL MRP showed scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. XL-1, XL-2 and XL-3 MRP exhibited about 50% redn. in absorbance of superoxide. Scavenging effects of XL MRP on DPPH radical and superoxide were markedly decreased after decolorization with Sep-Pak Cartridge C18, indicating that the browning pigment might contain components that can scavenge superoxide or donate hydrogen atoms. The ESR spectra indicated that XL MRP had scavenging activity on the hydroxyl radical; this scavenging effect depended on dose (r = 0.99) and increased with increasing duration of reaction. Based on these data, the antioxidative activity of XL MRP may be attributed to the combined effects of reducing power, donation of hydrogen atoms and scavenging of active oxygen.
28. 28
  Hennessy, D. J.; Reid, G. R.; Smith, F. E.; Thompson, S. L. Ferene ─ a New Spectrophotometric Reagent for Iron. Can. J. Chem. 1984, 62, 721– 724, DOI: 10.1139/v84-121
  28
  Ferene - a new spectrophotometric reagent for iron
  Hennessy, Douglas J.; Reid, Gary R.; Smith, Frank E.; Thompson, Stephen L.
  Canadian Journal of Chemistry (1984), 62 (4), 721-4CODEN: CJCHAG; ISSN:0008-4042.
  A ferene iron reagent, 3-(2-pyridyl)-5,6-bis(2-(5-furyl sulfonic acid)-1,2,4-triazine, disodium salt, monohydrate, was synthesized and characterized. Results of a study of its complex formation with Fe(II) including λmax, εmax, and log K values are reported. The title reagent is suggested for serum Fe detn. as a substitute for Ferrozine.
29. 29
  Feng, J.; Schroën, K.; Fogliano, V.; Berton-Carabin, C. Antioxidant Potential of Non-Modified and Glycated Soy Proteins in the Continuous Phase of Oil-in-Water Emulsions. Food Hydrocolloids 2021, 114, 106564, DOI: 10.1016/j.foodhyd.2020.106564
  29
  Antioxidant potential of non-modified and glycated soy proteins in the continuous phase of oil-in-water emulsions
  Feng, Jilu; Schroen, Karin; Fogliano, Vincenzo; Berton-Carabin, Claire
  Food Hydrocolloids (2021), 114 (), 106564CODEN: FOHYES; ISSN:0268-005X. (Elsevier Ltd.)
  Food emulsions with a high omega-3 polyunsatd. fatty acid content are desirable from a nutritional point of view. However, such products are particularly prone to lipid oxidn. and have thus a limited shelf-life. The use of natural antioxidants is a promising and consumer-oriented strategy to counteract lipid oxidn. The addn. of an excess of proteins to the continuous phase may be considered in that respect. Starting emulsions were prepd. with either Tween 20 (a nonionic surfactant) or whey protein isolate (WPI). They were then supplemented with non-modified or dextran-glycated soy protein isolate (SPI) added to the continuous phase. As controls, emulsions with excess WPI or unreacted SPI/dextran mixt. were also prepd. The addn. of these compds. did not significantly affect the phys. stability of emulsions, while the lipid oxidn. inhibition capacity was, starting from the highest, in the order glycated SPI mixt. > SPI/dextran mixt. > SPI > WPI. This suggests that SPI ingredients and dextran hold potential for mitigating lipid oxidn. in emulsions. The antioxidant mechanisms involved include iron-binding and free radical-scavenging activities; the former effect is predominant by preventing transition metals from approaching the oil-water interface. Furthermore, compared to WPI-stabilized emulsions, the antioxidant potential of excess proteins is boosted in Tween 20-stabilized emulsions. Interaction of surfactants with proteins could lead to a conformational change of proteins, which could increase their ability to bind mols. involved in the reaction cascade. This study shows that it is possible to tune emulsions towards greater oxidative stability by adjusting protein localization and continuous phase compn., which reduces the need for synthetic antioxidants.
30. 30
  Shantha, N. C.; Decker, E. A. Iron-Based Spectrophotometric Methods for Determination of Peroxide Values of Food Lipids. J. AOAC Int. 1994, 77, 421– 424, DOI: 10.1093/jaoac/77.2.421
  30
  Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids
  Shantha, Malur C.; Decker, Eric A.
  Journal of AOAC International (1994), 77 (2), 421-4CODEN: JAINEE; ISSN:1060-3271.
  The official International Dairy Federation method for detn. of the peroxide value of anhyd. milk fat was extended to poultry, meat, fish, and vegetable oils. The ferrous oxidn.-xylenol orange method for detn. of peroxide values of liposomes and lipoproteins was modified to make it simpler and more rapid. These 2 spectrophotometric methods were used successfully to det. the peroxide values of beef, chicken, butter, fish, and vegetable products. The results in most cases were consistent with those obtained by using the AOAC Official Method. The spectrophotometric methods have an assay time of less than 10 min, require ≤0.3 g fat, and are capable of detg. peroxide values as low as 0.1 mequiv/kg of sample.
31. 31
  AOCS. P-Anisidine Value─Official Method CD 18-90. Official Methods and Recommended Practices of the American Oil Chemists; AOCS Press: Champaign (USA), 1998.
  There is no corresponding record for this reference.
32. 32
  Bekedam, E. K.; Loots, M. J.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Roasting Effects on Formation Mechanisms of Coffee Brew Melanoidins. J. Agric. Food Chem. 2008, 56, 7138– 7145, DOI: 10.1021/jf800999a
  32
  Roasting effects on formation mechanisms of coffee brew melanoidins
  Bekedam, E. Koen; Loots, Mirjam J.; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
  Journal of Agricultural and Food Chemistry (2008), 56 (16), 7138-7145CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The effect of the roasting degree on coffee brew melanoidin properties and formation mechanisms was studied. Coffee brew fractions differing in mol. wt. (Mw) were isolated from green and light-, medium-, and dark-roasted coffee beans. Isolated fractions were characterized for their melanoidin, nitrogen, protein, phenolic groups, chlorogenic acid, quinic acid, caffeic acid, and sugar content. It was found that the melanoidin level in all fractions correlated with both the nitrogen and the protein content. The melanoidin level also correlated with the phenolic groups' level and ester-linked quinic acid level. It was concluded that proteins and chlorogenic acids should be primarily involved in melanoidin formation. Initial roasting, from green to light-roasted beans, esp. led to the formation of intermediate Mw (IMw) melanoidins when compared to high Mw (HMw) melanoidins. Indications were found that this IMw melanoidin formation is mainly due to Maillard reactions and chlorogenic acid incorporation reactions between chlorogenic acids, sucrose, and amino acids/protein fragments. Addnl., it was found that prolonged roasting predominantly led to formation melanoidins with a high Mw. Furthermore, arabinogalactans seem to be relatively more involved in melanoidin formation than galactomannans. It was hypothesized that chromophores may be formed or attached through the arabinose moiety of arabinogalactan proteins (AGP). Finally, it could be concluded that galactomannans are continuously incorporated in AGP-melanoidins upon roasting.
33. 33
  Oosterveld, A.; Harmsen, J. S.; Voragen, A. G. J.; Schols, H. A. Extraction and Characterization of Polysaccharides from Green and Roasted Coffea Arabica Beans. Carbohydr. Polym. 2003, 52, 285– 296, DOI: 10.1016/S0144-8617(02)00296-5
  33
  Extraction and characterization of polysaccharides from green and roasted Coffea arabica beans
  Oosterveld, A.; Harmsen, J. S.; Voragen, A. G. J.; Schols, H. A.
  Carbohydrate Polymers (2003), 52 (3), 285-296CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Science Ltd.)
  Polysaccharides were sequentially extd. from green and roasted Coffea arabica beans with water (90°), EDTA, 0.05, 1, and 4 M NaOH and characterized chem. Addnl., the beans were subjected to a single extn. with water at 170°. Green arabica coffee beans contained large proportions of 1→4-linked mannans, of which on av. 1 in every 23 mannopyranose residues was branched with single unit galactose side-chains at O-6. A part of these galactomannans could be extd. relatively easy with water and EDTA. These galactomannans were found to have a relatively high degree of branching (gal:man∼1:8) and a relatively low mol. wt. in comparison to the remaining galactomannans (gal:man∼1:15-24). Addnl., 1 3-linked galactans, heavily branched at O-6 with side-chains contg. arabinose and galactose residues, were present in the green coffee beans, as well as smaller amts. of pectins, cellulose, and xyloglucans. Roasting resulted in a loss of 8% of the dry wt. This could be partly explained by the relatively high percentage of sugars which was lost during the roasting process, most probably as a result of conversion into, e.g. Maillard and pyrolysis products. After roasting the extractability of polysaccharides was increased significantly. A decrease in the degree of branching as well as a decrease in mol. wt. of arabinogalactans, galactomannans, and xyloglucans was obsd. after roasting.
34. 34
  Tagliazucchi, D.; Verzelloni, E. Relationship between the Chemical Composition and the Biological Activities of Food Melanoidins. Food Sci. Biotechnol. 2014, 23, 561– 568, DOI: 10.1007/s10068-014-0077-5
  34
  Relationship between the chemical composition and the biological activities of food melanoidins
  Tagliazucchi, Davide; Verzelloni, Elena
  Food Science and Biotechnology (2014), 23 (2), 561-568CODEN: FSBOBR; ISSN:1226-7708. (Korean Society of Food Science and Technology)
  The relationship between the chem. compn. and the biol. activities of food melanoidin-rich fractions was investigated. Melanoidin-rich fractions were extd. using ultrafiltration (a 10 kDa cut-off) from coffee, barley coffee, dark beer, and traditional balsamic vinegar. All the food melanoidin-rich fractions were formed mainly of carbohydrates, phenolic compds., and proteins. In dark beer, barley coffee, and traditional balsamic vinegar melanoidins, glucose was the most abundant sugar incorporated into melanoidins. Coffee melanoidins contained the largest amt. of phenolic groups, followed by traditional balsamic vinegar melanoidins. The radical scavenging, Fe2+-chelating, and heme binding abilities of food melanoidins were investigated under gastric conditions. The melanoidin rich fraction extd. from coffee was the most active, showing the highest radical scavenging, Fe2+-chelating, and heme binding activities, compared to barley coffee, dark beer, and traditional balsamic vinegar. The radical scavenging and Fe2+-chelating abilities were assigned to the phenolic groups present in food melanoidins.
35. 35
  Lopes, G. R.; Ferreira, A. S.; Pinto, M.; Passos, C. P.; Coelho, E.; Rodrigues, C.; Figueira, C.; Rocha, S. M.; Nunes, F. M.; Coimbra, M. A. Carbohydrate Content, Dietary Fibre and Melanoidins: Composition of Espresso from Single-Dose Coffee Capsules. Food Res. Int. 2016, 89, 989– 996, DOI: 10.1016/j.foodres.2016.01.018
  35
  Carbohydrate content, dietary fibre and melanoidins: Composition of espresso from single-dose coffee capsules
  Lopes, Guido R.; Ferreira, Andreia S.; Pinto, Mariana; Passos, Claudia P.; Coelho, Elisabete; Rodrigues, Carla; Figueira, Claudia; Rocha, Silvia M.; Nunes, Fernando M.; Coimbra, Manuel A.
  Food Research International (2016), 89 (Part_2), 989-996CODEN: FORIEU; ISSN:0963-9969. (Elsevier B.V.)
  Single-dose coffee capsule system is a technol. used to prep. espresso coffee which offers consumers the possibility to choose among several blends. However, the characterization of espresso coffees extd. with these systems, namely regarding polysaccharides structures and melanoidin content, is scarce. In order to define a carbohydrate and melanoidin compn. pattern for single-dose espresso coffee base blends, a range of 6 com. espresso coffee blends was studied. In addn., a decaffeinated blend and a blend supplemented with plant natural exts. were also included. The base blends showed galactomannans as the predominant polysaccharides over arabinogalactans, on the contrary of the decaffeinated blend. The blend supplemented with natural plant exts. showed glucose-rich polysaccharides. The labeled intensity of coffee single-dose seems to be related with the unknown brown compds. of melanoidins, present in the high mol. wt. material of the brews. A pattern could be obtained for single-dose espresso coffee base blends, presenting an av. per cup of 1.21 g of total solids and 242 mg of sol. dietary fiber, constituted by 62 mg of galactomannans and 48 mg of arabinogalactans, and 123 mg of melanoidins. On av., 46% of espresso coffee low mol. wt. compds. are adsorbed to the high mol. wt. material, evidencing the importance of the adsorption/desorption phenomena for the properties of coffee dietary fiber.
36. 36
  Nunes, F. M.; Coimbra, M. A. Chemical Characterization of the High Molecular Weight Material Extracted with Hot Water from Green and Roasted Arabica Coffee. J. Agric. Food Chem. 2001, 49, 1773– 1782, DOI: 10.1021/jf0012953
  36
  Chemical Characterization of the High Molecular Weight Material Extracted with Hot Water from Green and Roasted Arabica Coffee
  Nunes, Fernando M.; Coimbra, Manuel A.
  Journal of Agricultural and Food Chemistry (2001), 49 (4), 1773-1782CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The polysaccharides present in coffee infusions are known to contribute to the organoleptic characteristics of the drink, such as the creamy sensation perceived in the mouth known as "body", the release of aroma substances, and the stability of espresso coffee foam. To increase the knowledge about the origin, compn., and structure of the polysaccharide fraction, the high mol. wt. material (HMWM) was extd. with hot water from 2 green and roasted ground arabica coffees: Costa Rica (wet processed) and Brazil (dry processed). The polysaccharides present in the green coffees HMWM were arabinogalactans (62%), galactomannans (24%), and glucans, and those found in roasted coffees were galactomannans (69%) and arabinogalactans (28%). The polysaccharides of the HMWM of the roasted coffees were less branched than those of the green coffees. The major green coffee proteins had mol. wts. of 58 and 38 kDa, and the 58 kDa protein had two subunits, of 38 and 20 kDa, possibly linked by disulfide bonds. The protein fraction obtained from roasted coffees had only a defined band with ≤14 kDa and a diffuse band with >200 kDa. The majority of the galactomannans were pptd. with solns. of 50% ethanol, and the size-exclusion chromatog. of the roasted fractions showed Co-elution of polysaccharides, proteins, phenolics, and brown compds. The use of strong hydrogen and hydrophobic dissocn. conditions allowed us to conclude that the phenolics and brown compds. were linked by covalent bonds to the polymeric material.
37. 37
  Simões, J.; Moreira, A. S. P.; Passos, C. P.; Nunes, F. M.; Domingues, M. R. M.; Coimbra, M. A. CHAPTER 19. Polysaccharides and Other Carbohydrates. In Coffee: Production, Quality and Chemistry; The Royal Society of Chemistry, 2019, pp 445– 457.
  There is no corresponding record for this reference.
38. 38
  Moreira, A. S. P.; Simões, J.; Pereira, A. T.; Passos, C. P.; Nunes, F. M.; Domingues, M. R. M.; Coimbra, M. A. Transglycosylation Reactions between Galactomannans and Arabinogalactans during Dry Thermal Treatment. Carbohydr. Polym. 2014, 112, 48– 55, DOI: 10.1016/j.carbpol.2014.05.031
  38
  Transglycosylation reactions between galactomannans and arabinogalactans during dry thermal treatment
  Moreira, Ana S. P.; Simoes, Joana; Pereira, Andreia T.; Passos, Claudia P.; Nunes, Fernando M.; Domingues, M. Rosario M.; Coimbra, Manuel A.
  Carbohydrate Polymers (2014), 112 (), 48-55CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)
  Aiming to investigate the possible occurrence of transglycosylation reactions between galactomannans and side chains of arabinogalactans during coffee roasting, mixts. of β-(1→4)-D-mannotriose and α-(1→5)-L-arabinotriose were subjected to dry thermal treatments at 200 °C. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) anal. allowed identifying polysaccharides composed by pentose and hexose residues with a d.p. up to 18 residues. Methylation anal. showed the occurrence of new types of glycosidic linkages in all thermally treated mixts., as well as the occurrence of terminally and 5-linked ribose, possibly formed from arabinose isomerization. Also, xylose and lyxose were identified and proposed to be formed from mannose. These results support the occurrence of transglycosylation reactions promoted by roasting involving both oligosaccharides in the starting mixts., resulting in arabinan and mannan chimeric polysaccharides. These structural features were also found in roasted coffee polysaccharide samples.
39. 39
  Ludwig, I. A.; Clifford, M. N.; Lean, M. E. J.; Ashihara, H.; Crozier, A. Coffee: Biochemistry and Potential Impact on Health. Food Funct. 2014, 5, 1695– 1717, DOI: 10.1039/c4fo00042k
  39
  Coffee: biochemistry and potential impact on health
  Ludwig, Iziar A.; Clifford, Michael N.; Lean, Michael E. J.; Ashihara, Hiroshi; Crozier, Alan
  Food & Function (2014), 5 (8), 1695-1717CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
  This review provides details on the phytochems. in green coffee beans and the changes that occur during roasting. Key compds. in the coffee beverage, produced from the ground, roasted beans, are volatile constituents responsible for the unique aroma, the alkaloids caffeine and trigonelline, chlorogenic acids, the diterpenes cafestol and kahweol, and melanoidins, which are Maillard reaction products. The fate of these compds. in the body following consumption of coffee is discussed along with evidence of the mechanisms by which they may impact health. Finally, epidemiol. findings linking coffee consumption to potential health benefits including prevention of several chronic and degenerative diseases, such as cancer, cardiovascular disorders, diabetes, and Parkinson's disease, are evaluated.
40. 40
  Bekedam, E. K.; Roos, E.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Low Molecular Weight Melanoidins in Coffee Brew. J. Agric. Food Chem. 2008, 56, 4060– 4067, DOI: 10.1021/jf8001894
  40
  Low molecular weight melanoidins in coffee brew
  Bekedam, E. Koen; Roos, Ellen; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
  Journal of Agricultural and Food Chemistry (2008), 56 (11), 4060-4067CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Anal. of low mol. wt. (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate anal. This study focused on the isolation of LMw coffee brew melanoidins by sepn. of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extn. and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were detd. The sugar compn., the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic anal. revealed that the melanoidins isolated showed similar features as high mol. wt. coffee melanoidins. All three melanoidin fractions contained ∼3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a neg. charge, and this neg. charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins.
41. 41
  Wei, F.; Tanokura, M. Chemical Changes in the Components of Coffee Beans during Roasting. Coffee in Health and Disease Prevention; Elsevier Inc., 2015.
  There is no corresponding record for this reference.
42. 42
  Ludwig, I. A.; Mena, P.; Calani, L.; Cid, C.; Del Rio, D.; Lean, M. E. J.; Crozier, A. Variations in Caffeine and Chlorogenic Acid Contents of Coffees: What Are We Drinking?. Food Funct. 2014, 5, 1718– 1726, DOI: 10.1039/c4fo00290c
  42
  Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking?
  Ludwig, Iziar A.; Mena, Pedro; Calani, Luca; Cid, Concepcion; Del Rio, Daniele; Lean, Michael E. J.; Crozier, Alan
  Food & Function (2014), 5 (8), 1718-1726CODEN: FFOUAI; ISSN:2042-6496. (Royal Society of Chemistry)
  The effect of roasting of coffee beans and the extn. of ground coffee with different vols. of hot pressurised water on the caffeine and the total caffeoylquinic acids (CQAs) content of the resultant beverages was investigated. While caffeine was stable higher roasting temps. resulted in a loss of CQAs so that the caffeine/CQA ratio was a good marker of the degree of roasting. The caffeine and CQA content and vol. was detd. for 104 espresso coffees obtained from coffee shops in Scotland, Italy and Spain, limited nos. of cappuccino coffees from com. outlets and several instant coffees. The caffeine content ranged from 48-317 mg per serving and CQAs from 6-188 mg. It is evident that the ingestion of 200 mg of caffeine per day can be readily and unwittingly exceeded by regular coffee drinkers. This is the upper limit of caffeine intake from all sources recommended by US and UK health agencies for pregnant women. In view of the variable vol. of serving sizes, it is also clear that the term "one cup of coffee" is not a reproducible measurement for consumption, yet it is the prevailing unit used in epidemiol. to assess coffee consumption and to link the potential effects of the beverage and its components on the outcome of diseases. More accurate measurement of the intake of coffee and its potentially bioactive components are required if epidemiol. studies are to produce more reliable information.
43. 43
  Bekedam, E. K.; Schols, H. A.; Van Boekel, M. A. J. S.; Smit, G. Incorporation of Chlorogenic Acids in Coffee Brew Melanoidins. J. Agric. Food Chem. 2008, 56, 2055– 2063, DOI: 10.1021/jf073157k
  43
  Incorporation of chlorogenic acids in coffee brew melanoidins
  Bekedam, E. Koen; Schols, Henk A.; Van Boekel, Martinus A. J. S.; Smit, Gerrit
  Journal of Agricultural and Food Chemistry (2008), 56 (6), 2055-2063CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The incorporation of chlorogenic acids (CGAs) and their subunits quinic and caffeic acids (QA and CA) in coffee brew melanoidins was studied. Fractions with different mol. wts., ionic charges, and ethanol solubilities were isolated from coffee brew. Fractions were sapond., and the released QA and CA were quantified. For all melanoidin fractions, it was found that more QA than CA was released. QA levels correlated with melanoidin levels, indicating that QA is incorporated in melanoidins. The QA level was correlated with increasing ionic charge of the melanoidin populations, suggesting that QA may contribute to the neg. charge and consequently is, most likely, not linked via its carboxyl group. The QA level correlated with the phenolic acid group level, as detd. by Folin-Ciocalteu, indicating that QA was incorporated to a similar extent as the polyphenolic moiety from CGA. The QA and CA released from brew fractions by enzymes confirmed the incorporation of intact CGAs. Intact CGAs are proposed to be incorporated in melanoidins upon roasting via CA through mainly nonester linkages. This complex can be written as Mel=CA-QA, in which Mel represents the melanoidin backbone, =CA represents CA nonester-linked to the melanoidin backbone, and -QA represents QA ester-linked to CA. Addnl., a total of 12% of QA was identified in coffee brew, whereas only 6% was reported in the literature so far. The relevance of the addnl. QA on coffee brew stability is discussed.
44. 44
  Silván, J. M.; Morales, F. J.; Saura-Calixto, F. Conceptual Study on Maillardized Dietary Fiber in Coffee. J. Agric. Food Chem. 2010, 58, 12244– 12249, DOI: 10.1021/jf102489u
  44
  Conceptual study on Maillardized dietary fiber in coffee
  Silvan, Jose Manuel; Morales, Francisco J.; Saura-Calixto, Fulgencio
  Journal of Agricultural and Food Chemistry (2010), 58 (23), 12244-12249CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  There is a methodol. and conceptual overlap between coffee melanoidins and dietary fiber. Green Uganda coffee beans were roasted in a range from 8.1 to 21.6% of wt. loss to evaluate melanoidins and dietary fiber. Samples were characterized by color, moisture, soly., water activity, carbohydrates, polyphenols, protein, sol. dietary fiber (SDF), and melanoidins content. Hydroxymethylfurfural and chlorogenic acids were also measured as chem. markers of the extent of roasting. Melanoidins rapidly increased from 5.6 (light roasting) to 29.1 mg/100 mg sol. dry matter (dark roasting). A melanoidins-like structure was already present in green coffee that might overestimate up to 21.0% of the melanoidins content as detd. by colorimetric methods. However, its contribution is variable and very likely depends on the method of drying applied to green coffee. SDF content (mg/100 mg sol. dry matter) gradually increased from 39.4 in green coffee to 64.9 at severe roasting conditions due to incorporation of neoformed colored structures and polyphenols. Then, SDF progressively turns to a maillardized structure, which increased from 11.0 to 45.0% according to the roasting conditions. It is concluded that the content of coffee melanoidins includes a substantial part of dietary fiber and also that coffee dietary fiber includes melanoidins. A conceptual discussion on a new definition of coffee melanoidins as a type of maillardized dietary fiber is conducted.
45. 45
  Schröder, A.; Berton-Carabin, C.; Venema, P.; Cornacchia, L. Interfacial Properties of Whey Protein and Whey Protein Hydrolysates and Their Influence on O/W Emulsion Stability. Food Hydrocolloids 2017, 73, 129– 140, DOI: 10.1016/j.foodhyd.2017.06.001
  There is no corresponding record for this reference.
46. 46
  Redgwell, R. J.; Schmitt, C.; Beaulieu, M.; Curti, D. Hydrocolloids from Coffee: Physicochemical and Functional Properties of an Arabinogalactan-Protein Fraction from Green Beans. Food Hydrocolloids 2005, 19, 1005– 1015, DOI: 10.1016/j.foodhyd.2004.12.010
  46
  Hydrocolloids from coffee: physicochemical and functional properties of an arabinogalactan-protein fraction from green beans
  Redgwell, R. J.; Schmitt, C.; Beaulieu, M.; Curti, D.
  Food Hydrocolloids (2005), 19 (6), 1005-1015CODEN: FOHYES; ISSN:0268-005X. (Elsevier B.V.)
  The arabinogalactan-protein (AGP) fraction of green coffee beans accounts for ∼15% of the dry bean. A procedure was developed to solubilize most of the AGP content of the beans so that its properties as a hydrocolloid could be investigated. An AGP fraction was partially purified from green arabica coffee beans, its rheol. properties characterized and compared to those of some com. important hydrocolloids, particularly acacia gum. The coffee AGP fraction dissolved readily in water to give colorless clear solns. The polymer was a polyelectrolyte with a high mol. wt. (Mw 3.78×106), characterized by a narrow polydispersity index (Mw/Mn 1.3). The intrinsic viscosity was close to that of acacia gum ([η]=0.23 dL g-1), but a 1 wt% soln. of coffee AGP was three times more viscous than acacia gum at the same concn. Coffee AGP showed Newtonian flow for concns. below 6 wt%, but above this concn. the flow behavior entered a shear-thinning regime. The coffee AGP fraction possessed interesting foaming properties providing that the biopolymer concn. was high enough to initially stabilize the interface that is created. The high mol. wt. of coffee AGP combined with its globular structure conferred upon it a high ability to retain water within a foam thin film. However, the structure of the interfacial film was less effective than that of acacia gum to entrap efficiently the gas into the foam. In summary, coffee AGP shows some interesting rheol. features which suggest that coffee beans could be used as an alternative source of the class of surface-active polymers which find many com. applications.
47. 47
  St. Angelo, A. J.; Vercellotti, J.; Jacks, T.; Legendre, M. Lipid Oxidation in Foods; American Chemical Society, 1996; Vol. 36.
  There is no corresponding record for this reference.
48. 48
  Chen, B.; McClements, D. J.; Decker, E. A. Minor Components in Food Oils: A Critical Review of Their Roles on Lipid Oxidation Chemistry in Bulk Oils and Emulsions. Crit. Rev. Food Sci. Nutr. 2011, 51, 901– 916, DOI: 10.1080/10408398.2011.606379
  48
  Minor Components in Food Oils: A Critical Review of their Roles on Lipid Oxidation Chemistry in Bulk Oils and Emulsions
  Chen, Bingcan; McClements, David Julian; Decker, Eric Andrew
  Critical Reviews in Food Science and Nutrition (2011), 51 (10), 901-916CODEN: CRFND6; ISSN:1040-8398. (Taylor & Francis, Inc.)
  A review. Food oils are primarily composed of triacylglycerols (TAG), but they may also contain a variety of other minor constituents that influence their phys. and chem. properties, including diacylglycerols (DAG), monoacylglycerols (MAG), free fatty acids (FFA), phospholipids (PLs), water, and minerals. This article reviews recent research on the impact of these minor components on lipid oxidn. in bulk oils and oil-in-water emulsions. In particular, it highlights the origin of these minor components, the influence of oil refining on the type and concn. of minor components present, and potential physicochem. mechanisms by which these minor components impact lipid oxidn. in bulk oils and emulsions. This knowledge is crucial for designing food, pharmaceutical, personal care, and other products with improved stability to lipid oxidn.
49. 49
  Tian, L.; Kejing, K.; Zhang, S.; Yi, J.; Zhu, Z.; Decker, E. A.; McClements, D. J. Impact of Tea Polyphenols on the Stability of Oil-in-Water Emulsions Coated by Whey Proteins. Food Chem. 2021, 343, 128448, DOI: 10.1016/j.foodchem.2020.128448
  49
  Impact of tea polyphenols on the stability of oil-in-water emulsions coated by whey proteins
  Tian, Li; Yang, Kejing; Zhang, Shulin; Yi, Jianhua; Zhu, Zhenbao; Decker, Eric Andrew; McClements, David Julian
  Food Chemistry (2021), 343 (), 128448CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
  The ability of tea polyphenols (0, 0.01, 0.02 or 0.04 w/v %) to inhibit lipid and protein oxidn. in walnut oil-in-water (O/W) emulsions was examd., as well as to alter their stability to aggregation and creaming. The lipid droplets in these emulsions were coated by whey proteins. The phys. stability of the emulsions during storage (50°C, 96 h) was improved by addn. of 0.01% tea polyphenols, but reduced when higher levels were added. Low levels (0.01%) of tea polyphenols inhibited lipid oxidn. (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidn. (carbonyl and Schiff base formation, sulfhydryl and intrinsic fluorescence loss, and mol. wt. changes). However, high levels (0.04%) of tea polyphenols were less effective at inhibiting lipid oxidn., and actually promoted protein oxidn. Tea polyphenols are natural antioxidants that can enhance the quality and shelf life of emulsified polyunsatd. lipids when used at an appropriate concn.
50. 50
  Faraji, H.; McClements, D. J.; Decker, E. A. Role of Continuous Phase Protein on the Oxidative Stability of Fish Oil-in-Water Emulsions. J. Agric. Food Chem. 2004, 52, 4558– 4564, DOI: 10.1021/jf035346i
  50
  Role of Continuous Phase Protein on the Oxidative Stability of Fish Oil-in-Water Emulsions
  Faraji, Habibollah; McClements, D. Julian; Decker, Eric A.
  Journal of Agricultural and Food Chemistry (2004), 52 (14), 4558-4564CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidn. when they produce a pos. charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the continuous phase. The impact of these continuous phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepd. by high-pressure homogenization. In some expts. WPI was removed from the continuous phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that continuous phase proteins were antioxidative. The oxidative stability of emulsions contg. different kinds of protein in the continuous phase decreased in the order SPI > CAS > WPI, as detd. by both hydroperoxide and headspace propanal formation. Iron-binding studies showed that the chelating ability of the proteins decreased in the order CAS > SPI > WPI. The free sulfhydryls of both WPI and SPI were involved in their antioxidant activity. This research shows that continuous phase proteins could be an effective means of protecting ω-3 fatty acids from oxidative deterioration.
51. 51
  Kaushik, P.; Dowling, K.; McKnight, S.; Barrow, C. J.; Wang, B.; Adhikari, B. Preparation, Characterization and Functional Properties of Flax Seed Protein Isolate. Food Chem. 2016, 197, 212– 220, DOI: 10.1016/j.foodchem.2015.09.106
  51
  Preparation, characterization and functional properties of flax seed protein isolate
  Kaushik, Pratibha; Dowling, Kim; McKnight, Stafford; Barrow, Colin J.; Wang, Bo; Adhikari, Benu
  Food Chemistry (2016), 197 (Part_A), 212-220CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
  Flaxseed protein isolate (FPI) was extd. from flaxseeds, and its amino acid compn. and functional properties (soly., thermal stability, emulsifying properties and electrostatic charge d., water-holding and fat-absorption capacities) were detd. The highest purity of FPI (90.6%) was achieved by extn. at 60 °C. FPI had a low lysine to arginine ratio of 0.25, which is desired in heart-healthy foods and infant formulas. The denaturation temp. of FPI was 105 °C. FPI had the highest emulsion activity index (375.51 m2/g), highest emulsion stability index (179.5 h) and zeta potential (-67.4 mV) when compared to those of other commonly used proteins, such as sodium caseinate (SC), whey protein isolate (WPI), gelatin (Gel) and soy protein isolate (SPI). The av. emulsion droplet size of emulsions stabilized by these proteins was in the order SC < FPI < WPI < Gel < SPI. Water-holding and fat-absorption capacities of FPI were similar to those of the above-mentioned proteins.
52. 52
  Borrelli, R. C.; Visconti, A.; Mennella, C.; Anese, M.; Fogliano, V. Chemical Characterization and Antioxidant Properties of Coffee Melanoidins. J. Agric. Food Chem. 2002, 50, 6527– 6533, DOI: 10.1021/jf025686o
  52
  Chemical Characterization and Antioxidant Properties of Coffee Melanoidins
  Borrelli, Rosa Cinzia; Visconti, Attilio; Mennella, Carmela; Anese, Monica; Fogliano, Vincenzo
  Journal of Agricultural and Food Chemistry (2002), 50 (22), 6527-6533CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Melanoidins, the brown polymers formed through Maillard reaction during coffee roasting, constitute up to 25% of the coffee beverages' dry matter. In this study chem. characterization of melanoidins obtained from light-, medium-, and dark-roasted coffee beans, manufd. from the same starting material, was performed. Melanoidins were sepd. by gel filtration chromatog. and studied by MALDI-TOF mass spectrometry. Results showed that the amt. of melanoidins present in the brews increased as the intensity of the thermal treatment increased, while their mol. wt. decreased. The antioxidant activity of melanoidins isolated from the different brews was studied by using different methodologies. Melanoidins antiradical activity detd. by ABTS•+ and DMPD•+ assays decreased as the intensity of roasting increased, but the ability to prevent linoleic acid peroxidn. was higher in the dark-roasted samples. Data suggest that melanoidins must be carefully considered when the relevance of coffee intake in human health is studied.
53. 53
  Wang, H. Y.; Qian, H.; Yao, W. R. Melanoidins Produced by the Maillard Reaction: Structure and Biological Activity. Food Chem. 2011, 128, 573– 584, DOI: 10.1016/j.foodchem.2011.03.075
  53
  Melanoidins produced by the Maillard reaction: Structure and biological activity
  Wang, He-Ya; Qian, He; Yao, Wei-Rong
  Food Chemistry (2011), 128 (3), 573-584CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
  A review. Melanoidins are compds. generated in the late stages of the Maillard reaction from reducing sugars and proteins or amino acids during food processing and preservation. Recently the effects of melanoidins on human health and the chem. characterization of the beneficial components have gained a lot of attention. Food melanoidins have been reported to be anionic, colored compds. and some of their key chromophores have been elucidated. The antioxidant activity and other biol. effects of melanoidins from real foods and model systems have been widely studied. Despite this, very few different melanoidin structures have actually been described, and specific health effects have yet to be linked to chem. distinct melanoidins. The variety of different Maillard reaction products formed during the reaction, in conjunction with the difficulty in purifying and identifying them, makes a thorough anal. of melanoidins challenging. This review provides a comprehensive look at what is known to date about melanoidin structure, the formation mechanism for these compds., and the biol. properties related to the beneficial health effects of melanoidins.
54. 54
  Kim, J. Y.; Kim, S.; Han, S.; Han, S. Y.; Passos, C. P.; Seo, J.; Lee, H.; Kang, E. K.; Mano, J. F.; Coimbra, M. A.; Park, J. H.; Choi, I. S. Coffee Melanoidin-Based Multipurpose Film Formation: Application to Single-Cell Nanoencapsulation. ChemNanoMat 2020, 6, 379– 385, DOI: 10.1002/cnma.202000004
  54
  Coffee Melanoidin-Based Multipurpose Film Formation: Application to Single-Cell Nanoencapsulation
  Kim, Ji Yup; Kim, Seulbi; Han, Sol; Han, Sang Yeong; Passos, Claudia P.; Seo, Jeongyeon; Lee, Hojae; Kang, Eunhye K.; Mano, Joao F.; Coimbra, Manuel A.; Park, Ji Hun; Choi, Insung S.
  ChemNanoMat (2020), 6 (3), 379-385CODEN: CHEMSB; ISSN:2199-692X. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The melanoidin from sol. coffee is utilized as a material-independent, multipurpose coating material. Instantaneous complexation of the coffee melanoidin (CM) with ferric ion (Fe3+) leads to surface-adhesive aggregates, inducing sequential film deposition. Various chem. groups of the CM also allow for post-functionalizations of the CM film, including surface-initiated, ring-opening polymn. and bioinspired silicification. In addn., the CM-based coating is applied to single-cell nanoencapsulation with a strategy of biphasic interfacial reactions. The method is highly cytocompatible (viability >98%), and the CM shell is cytoprotective against lytic enzymes. The coated cells inherit the characterictics of the CM, such as post-functionalizability and antioxidant property. Considering that surface-coating technologies with cytocompatible natural polymers have widely been used for engineering bioentities, the CM-based coating strategy would provide an advanced option for biomedical applications.
55. 55
  Troup, G. J.; Navarini, L.; Liverani, F. S.; Drew, S. C. Stable Radical Content and Anti-Radical Activity of Roasted Arabica Coffee: From in-Tact Bean to Coffee Brew. PLoS One 2015, 10, e0122834 DOI: 10.1371/journal.pone.0122834
  55
  Stable radical content and anti-radical activity of roasted arabica coffee: from in-tact bean to coffee brew
  Troup, Gordon J.; Navarini, Luciano; Liverani, Furio Suggi; Drew, Simon C.
  PLoS One (2015), 10 (4), e0122834/1-e0122834/17CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
  The roasting of coffee beans generates stable radicals within melanoidins produced by non-enzymic browning. Roasting coffee beans has further been suggested to increase the antioxidant (AO) capacity of coffee brews. Herein, we have characterized the radical content and AO capacity of brews prepd. from Coffea arabica beans sourced directly from an industrial roasting plant. In-tact beans exhibited ESR signals arising from Fe3+, Mn2+ and at least three distinct stable radicals as a function of roasting time, whose intensity changed upon grinding and ageing. In coffee brews, the roasting-induced radicals were harboured within the high mol. wt. (> 3 kD) melanoidin- contg. fraction at a concn. of 15 nM and was assocd. with arom. groups within the melanoidins. The low mol. wt. (< 3 kD) fraction exhibited the highest AO capacity using DPPH as an oxidant. The AO activity was not mediated by the stable radicals or by metal complexes within the brew. While other non-AO functions of the roasting-induced radical and metal complexes may be possible in vivo, we confirm that the in vitro antiradical activity of brewed coffee is dominated by low mol. wt. phenolic compds.
56. 56
  Samsonowicz, M.; Regulska, E.; Karpowicz, D.; Leśniewska, B. Antioxidant Properties of Coffee Substitutes Rich in Polyphenols and Minerals. Food Chem. 2019, 278, 101– 109, DOI: 10.1016/j.foodchem.2018.11.057
  56
  Antioxidant properties of coffee substitutes rich in polyphenols and minerals
  Samsonowicz, Mariola; Regulska, Ewa; Karpowicz, Danuta; Lesniewska, Barbara
  Food Chemistry (2019), 278 (), 101-109CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)
  The anal. of general content of polyphenols, minerals and antioxidant activity of infusions from selected coffee substitutes is presented. The obtained results showed that the coffee infusions prepd. from acorns exhibit the highest radical scavenging capacities for DPPH (EC50 = 0.063-0.066 mgd.w./mL), ABTS (EC50 = 0.021-0.029 mgd.w./mL), OH·(EC50 = 2.050-2.378 mgd.w./mL) as well as the highest ability to Fe3+ redn. (FRAP) (∼1.1 mmolFe/gd.w). These coffee substitutes also contain the greatest values of polyphenols (45-50 mgGA/gd.w). Analyzed coffee substitutes differ in both quality and quantity of polyphenols, but all tested coffees contain gallic and chlorogenic acids. The most of phenolic compds. was found in herbal-cereal coffee substitute. The quant. results and PCA anal. indicated a good correlation between the antioxidant activity and total polyphenols, flavonoids and gallic acid content. Using the obtained data on the compn. and antioxidant properties of exts. the cluster anal. (CA) was performed to distinguish similar or close types of coffee.
57. 57
  Laguerre, M.; Tenon, M.; Bily, A.; Birtić, S. Toward a Spatiotemporal Model of Oxidation in Lipid Dispersions: A Hypothesis-Driven Review. Eur. J. Lipid Sci. Technol. 2020, 122, 1900209, DOI: 10.1002/ejlt.201900209
  57
  Toward a Spatiotemporal Model of Oxidation in Lipid Dispersions: A Hypothesis-Driven Review
  Laguerre, Mickael; Tenon, Mathieu; Bily, Antoine; Birtic, Simona
  European Journal of Lipid Science and Technology (2020), 122 (3), 1900209CODEN: EJLTFM; ISSN:1438-7697. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Unsatd. lipids are prone to get oxidized through a sequence of reactions known as lipid oxidn. From a phenomenon considered at the beginning as a mere chem. process and described by the triptych of initiation, propagation, and termination, the vision of lipid oxidn. has progressively evolved to further integrate the phys. dimension of the phenomenon. Despite tremendous research efforts, however, this sequence of reactions is not yet well understood, esp. in lipid dispersions where many facts are still inexplicable and unpredictable under the current paradigm. Here, the aim is to suggest that the main reason why a better understanding has not already been achieved is that the reactional network is not yet organized in a coherent spatiotemporal framework. The novel concepts and hypotheses proposed in this article may help redirecting a significant part of research efforts toward the establishment of a spatially and temporally resolved model of oxidn. in dispersed lipids. Practical Application: Predicting how oxidn. spreads in lipid dispersions represents a goal of crucial importance for academia but also for industry. Such prediction models would indeed greatly help food manufacturers prevent oxidn. by using the most adapted antioxidative strategies for their specific products. To achieve such an objective, it is proposed that the first thing to do is to go beyond the extremely reductive and narrow framework in which this chem. process has been locked in. Indeed, while lipid dispersions are composed of a multitude of lipid colloids, researchers usually consider oxidn. at the sole level of an individual droplet or membrane. Instead, lipid oxidn. is advocated as a dynamic trafficking of chem. species within large communities of different colloidal objects such as droplets, membranes, or micelles dispersed in water-a system that dubbed "colloidal ecosystem". This might represent a scale complementary to the scales of individual colloids or mols. that were the sole consideration so far to try torepresent lipid oxidn. Only then can one hope to effectively apply modeling and "omics" approaches, as is explained in more details in this article.
58. 58
  Morales, F. J.; Jiménez-Pérez, S. Peroxyl Radical Scavenging Activity of Melanoidins in Aqueous Systems. Eur. Food Res. Technol. 2004, 218, 515– 520, DOI: 10.1007/s00217-004-0896-3
  58
  Peroxyl radical scavenging activity of melanoidins in aqueous systems
  Morales, Francisco J.; Jimenez-Perez, Salvio
  European Food Research and Technology (2004), 218 (6), 515-520CODEN: EFRTFO; ISSN:1438-2377. (Springer-Verlag)
  Melanoidins are widely distributed in our diet, due to home or industrial processing of foods. Until recently, melanoidins were considered to be an inert, brown-colored polymeric component. However, recent research into their nutritional, physiol., and functional properties has suggested that they have antioxidant properties, and we address this issue in this work. A sensitive procedure for assessing the inhibition of lipid peroxidn. by melanoidins in watery media has been developed. Main drawbacks and crit. steps of the procedure are discussed. Melanoidins can be classified according to the no. of peroxyl radicals trapped per mol. Coffee and sweet wine melanoidins show higher antioxidant activity than melanoidins isolated from beer. For the first time, a linear relationship between the peroxyl radical scavenging activity and the chromophore residues in the melanoidin skeleton responsible for browning has been established.
59. 59
  Pérez-Martínez, M.; Caemmerer, B.; De Peña, M. P.; Cid, C.; Kroh, L. W. Influence of Brewing Method and Acidity Regulators on the Antioxidant Capacity of Coffee Brews. J. Agric. Food Chem. 2010, 58, 2958– 2965, DOI: 10.1021/jf9037375
  59
  Influence of Brewing Method and Acidity Regulators on the Antioxidant Capacity of Coffee Brews
  Perez-Martinez, Monica; Caemmerer, Bettina; De Pena, M. Paz; Cid, Concepcion; Kroh, Lothar W.
  Journal of Agricultural and Food Chemistry (2010), 58 (5), 2958-2965CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The antioxidant capacity of coffee brews prepd. with different coffeemakers (filter, plunger, mocha, and espresso) was measured by colorimetric (total phenolic compds. and ABTS) and ESR spectroscopy techniques (Fremy's salt and TEMPO). The mocha coffeemaker had the highest yield in coffee antioxidant extn. per g of ground roasted coffee, but espresso coffee was richest in terms of antioxidant intake (per milliliter of coffee brew) followed by mocha, plunger, and filter. Both Folin-Ciocalteu (total phenolic compds.) and ABTS assays reacted with std. solns. of chlorogenic acids (CGA) and melanoidins (MO-Ala and MO-Gly). However, Fremy's salt was mainly scavenged by chlorogenic acids, whereas the stabilized radical TEMPO was effectively scavenged by melanoidins, but not by chlorogenic acids. Thus, ESR spectroscopy allows distinguishing between phenolic and nonphenolic antioxidants. Moreover, the addn. of pH-regulator agents to coffee, such as sodium carbonate (75 ppm) and bicarbonate (75 ppm), to extend its shelf life, slightly increases the pH, modifying the antioxidant capacity in those coffee brews with the highest capacity (mocha and espresso).
60. 60
  Kellerby, S. S.; McClements, D. J.; Decker, E. A. Role of Proteins in Oil-in-Water Emulsions on the Stability of Lipid Hydroperoxides. J. Agric. Food Chem. 2006, 54, 7879– 7884, DOI: 10.1021/jf061340s
  60
  Role of Proteins in Oil-in-Water Emulsions on the Stability of Lipid Hydroperoxides
  Kellerby, Sarah S.; McClements, D. Julian; Decker, Eric A.
  Journal of Agricultural and Food Chemistry (2006), 54 (20), 7879-7884CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  The purpose of this research was to better understand the mechanisms by which proteins affect the rates of lipid oxidn. in order to develop protein-stabilized emulsion delivery systems with maximal oxidative stability. This study evaluated the affect of pH and emulsifier concn. on the stability of cumene hydroperoxide in hexadecane-in-water emulsions stabilized by β-lactoglobulin (β-Lg). Emulsions prepd. with 0.2 wt % β-Lg (at pH 7.0) showed a 26.9% decrease in hydroperoxide concns. 5 min after 0.25 mM ferrous ion was added to the emulsion. EDTA, but not continuous phase β-Lg, could inhibit Fe-promoted lipid hydroperoxide decompn. Lipid hydroperoxides were more stable to Fe-promoted degrdn. at pH values below the pI of β-Lg, where the emulsion droplet would be cationic and thus able to repel Fe away from the lipid hydroperoxides. Heating the β-Lg-stabilized emulsions to produce a cohesive protein layer on the emulsion droplet surface did not alter the ability of Fe to decomp. lipid hydroperoxides. These results suggest that proteins at the interface of emulsion droplets primarily stabilize lipid hydroperoxides by electrostatically inhibiting Fe-hydroperoxide interactions.
61. 61
  Ćosović, B.; Vojvodić, V.; Bošković, N.; Plavšić, M.; Lee, C. Characterization of Natural and Synthetic Humic Substances (Melanoidins) by Chemical Composition and Adsorption Measurements. Org. Geochem. 2010, 41, 200– 205, DOI: 10.1016/j.orggeochem.2009.10.002
  61
  Characterization of natural and synthetic humic substances (melanoidins) by chemical composition and adsorption measurements
  Cosovic, Bozena; Vojvodic, Vjerocka; Boskovic, Nikola; Plavsic, Marta; Lee, Cindy
  Organic Geochemistry (2010), 41 (2), 200-205CODEN: ORGEDE; ISSN:0146-6380. (Elsevier Ltd.)
  Melanoidins, condensation products of sugars and amino acids, are thought to represent a key link in the transformation of polysaccharides and proteins to humic material in the marine environment. We studied adsorption behavior of melanoidins prepd. in equimolar solns. of glucose and amino acids of choice (glutamic acid, valine and lysine) and pseudomelanoidins which were prepd. from glucose only. Melanoidins were prepd. using different condensation times (2, 4, 16 and 32 days). Synthesized melanoidins were sepd. into different mol. mass fractions. Fractionation of melanoidins by sorption on the macroreticular resin XAD-8 sepd. melanoidins into hydrophobic neutral, hydrophobic acid and hydrophilic fractions. Adsorption of melanoidins and their different fractions was studied at a Hg electrode by directly measuring the change of the double layer capacitance caused by the adsorption of org. mols. on the electrode surface through phase sensitive a.c. voltammetry. The hydrophobic acid fraction of melanoidins accounted for most of the adsorption behavior of melanoidins. Consequently, the higher mol. mass fraction of melanoidins (>10 KDa) exhibits a stronger adsorption in comparison to the lower mol. mass fraction (<3 KDa) of the same melanoidin. The good fit of adsorption data of melanoidins and pseudomelanoidins to the same adsorption isotherm supports the idea that melanoidins are comprised of a sugar derived backbone that is responsible for the adsorption behavior of melanoidin, while the presence of N atoms is responsible for the complexation of Cu ions. Adsorption characteristics and complexation ability of melanoidins and natural org. matter were similar. Our results suggest that in the process of humification, selective adsorption of condensation products on aq. surfaces may lead to a progressive immobilization of certain fractions, i.e., it is probable that higher mol. mass components accumulate at aquatic surfaces, while lower mass components remain in soln.
62. 62
  Schröder, A.; Laguerre, M.; Sprakel, J.; Schroën, K.; Berton-Carabin, C. C. Pickering Particles as Interfacial Reservoirs of Antioxidants. J. Colloid Interface Sci. 2020, 575, 489– 498, DOI: 10.1016/j.jcis.2020.04.069
  62
  Pickering particles as interfacial reservoirs of antioxidants
  Schroder, Anja; Laguerre, Mickael; Sprakel, Joris; Schroen, Karin; Berton-Carabin, Claire C.
  Journal of Colloid and Interface Science (2020), 575 (), 489-498CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
  Emulsions are common structures encapsulating lipophilic bioactive mols., both in biol. systems and in manufd. products. Protecting these functional mols. from oxidn. is essential; Nature excels at doing so by placing antioxidants at the oil-water interface, where oxidative reactions primarily occur. We imagined a novel approach to boost the activity of antioxidants in designer emulsions by employing Pickering particles that act both as phys. emulsion stabilizers and as interfacial reservoirs of antioxidants.α-Tocopherol or carnosic acid, two model lipophilic antioxidants, were entrapped in colloidal lipid particles (CLPs) that were next used to phys. stabilize sunflower oil-in-water emulsions ("concept" Pickering emulsions). We first assessed the phys. properties and stability of the CLPs and of the Pickering emulsions. We then monitored the oxidative stability of the concept emulsions upon incubation, and compared it to that of control emulsions of similar structure, yet with the antioxidant present in the oil droplet interior. Both tested antioxidants are largely more effective when loaded within Pickering particles than when solubilized in the oil droplet interior, thus confirming the importance of the interfacial localization of antioxidants. This approach revisits the paradigm for lipid oxidn. prevention in emulsions and offers potential for many applications.
63. 63
  Xu, M.; Jin, Z.; Ohm, J. B.; Schwarz, P.; Rao, J.; Chen, B. Improvement of the Antioxidative Activity of Soluble Phenolic Compounds in Chickpea by Germination. J. Agric. Food Chem. 2018, 66, 6179– 6187, DOI: 10.1021/acs.jafc.8b02208
  63
  Improvement of the Antioxidative Activity of Soluble Phenolic Compounds in Chickpea by Germination
  Xu, Minwei; Jin, Zhao; Ohm, Jae-Bom; Schwarz, Paul; Rao, Jiajia; Chen, Bingcan
  Journal of Agricultural and Food Chemistry (2018), 66 (24), 6179-6187CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)
  Our recent study found that antioxidative activity of phenolic compds. extd. from germinated chickpea was boosted both in an in vitro assays and in oil-in-water emulsion. The purpose of this study was to elucidate the mechanism by which the compn. of phenolic compds. extd. from chickpea germination enhances its antioxidative activity. Liq. chromatog. coupled with electrospray ionization quadrupole time of flight mass spectrometry (LC-ESI-QTOF-MS) and size-exclusion chromatog. with multi-angle light-scattering and refractive index detection (SEC-MALS-RI) were employed to evaluate the phenolic compn. of sol. phenolic compds. (free and bound) and molar mass of sol. bound phenolic compds., resp., over the period of 6 days germination. According to principal component anal. of the interrelationship between germination time and phenolic compn., it is revealed that protocatechuic acid 4-O-glucoside and 6-hydroxydaidzein played a pivotal role in the sol. free phenolic compds., while gentisic acid and 7,3',4'-trihydroxyflavone were important in the sol. bound phenolic compds. Molar masses of sol. bound phenolic compds. were increased after 6 days germination. A protective and/or a dual antioxidative effects were proposed to explicate how antioxidative activity of sol. bound phenolic compds. in oil-in-water emulsions was improved with germination.
64. 64
  Perron, N. R.; Brumaghim, J. L. A Review of the Antioxidant Mechanisms of Polyphenol Compounds Related to Iron Binding. Cell Biochem. Biophys. 2009, 53, 75– 100, DOI: 10.1007/s12013-009-9043-x
  64
  A Review of the Antioxidant Mechanisms of Polyphenol Compounds Related to Iron Binding
  Perron, Nathan R.; Brumaghim, Julia L.
  Cell Biochemistry and Biophysics (2009), 53 (2), 75-100CODEN: CBBIFV; ISSN:1085-9195. (Springer)
  A review. In this review, primary attention is given to the antioxidant (and prooxidant) activity of polyphenols arising from their interactions with iron both in vitro and in vivo. In addn., an overview of oxidative stress and the Fenton reaction is provided, as well as a discussion of the chem. of iron binding by catecholate, gallate, and semiquinone ligands along with their stability consts., UV-vis spectra, stoichiometries in soln. as a function of pH, rates of iron oxidn. by O2 upon polyphenol binding, and the published crystal structures for iron-polyphenol complexes. Radical scavenging mechanisms of polyphenols unrelated to iron binding, their interactions with copper, and the prooxidant activity of iron-polyphenol complexes are briefly discussed.
65. 65
  Timoshnikov, V. A.; Kobzeva, T. v.; Polyakov, N. E.; Kontoghiorghes, G. J. Redox Interactions of Vitamin c and Iron: Inhibition of the pro-Oxidant Activity by Deferiprone. Int. J. Mol. Sci. 2020, 21, 3967, DOI: 10.3390/ijms21113967
  65
  Redox interactions of vitamin C and iron: inhibition of the pro-oxidant activity by deferiprone
  Timoshnikov, Viktor A.; Kobzeva, Tatyana V.; Polyakov, Nikolay E.; Kontoghiorghes, George J.
  International Journal of Molecular Sciences (2020), 21 (11), 3967CODEN: IJMCFK; ISSN:1422-0067. (MDPI AG)
  Ascorbic acid (AscH2) is one of the most important vitamins found in the human diet, with many biol. functions including antioxidant, chelating, and coenzyme activities. Ascorbic acid is also widely used in medical practice esp. for increasing iron absorption and as an adjuvant therapeutic in iron chelation therapy, but its mode of action and implications in iron metab. and toxicity are not yet clear. In this study, we used UV-Vis spectrophotometry, NMR spectroscopy, and EPR spin trapping spectroscopy to investigate the antioxidant/pro-oxidant effects of ascorbic acid in reactions involving iron and the iron chelator deferiprone (L1). The expts. were carried out in a weak acidic (pH from 3 to 5) and neutral (pH 7.4) medium. Ascorbic acid exhibits predominantly pro-oxidant activity by reducing Fe3+ to Fe2+, followed by the formation of dehydroascorbic acid. As a result, ascorbic acid accelerates the redox cycle Fe3+ ↔ Fe2+ in the Fenton reaction, which leads to a significant increase in the yield of toxic hydroxyl radicals. The anal. of the exptl. data suggests that despite a much lower stability const. of the iron-ascorbate complex compared to the FeL13 complex, ascorbic acid at high concns. is able to substitute L1 in the FeL13 chelate complex resulting in the formation of mixed L12AscFe complex. This mixed chelate complex is redox stable at neutral pH = 7.4, but decomps. at pH = 4-5 during several minutes at sub-millimolar concns. of ascorbic acid. The proposed mechanisms play a significant role in understanding the mechanism of action, pharmacol., therapeutic, and toxic effects of the interaction of ascorbic acid, iron, and L1.
66. 66
  Liang, N.; Kitts, D. D. Antioxidant Property of Coffee Components: Assessment of Methods That Define Mechanism of Action. Molecules 2014, 19, 19180– 19208, DOI: 10.3390/molecules191119180
  66
  Antioxidant property of coffee components: assessment of methods that define mechanisms of action
  Liang, Ningjian; Kitts, David D.
  Molecules (2014), 19 (11), 19180-19208, 29 pp.CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)
  A review. Coffee is a rich source of dietary antioxidants, and this property, coupled with the fact that coffee is one of the world' s most popular beverages, has led to the understanding that coffee is a major contributor to dietary antioxidant intake. Brewed coffee is a complex food matrix with numerous phytochem. components that have antioxidant activity capable of scavenging free radicals, donating hydrogen and electrons, providing reducing activity and also acting as metal ion pro-oxidant chelators. More recent studies have shown that coffee components can trigger tissue antioxidant gene expression and protect against gastrointestinal oxidative stress. This paper will describe different in vitro, cell-free and cell-based assays that both characterize and compare the antioxidant capacity and mechanism of action of coffee and its bioactive constituents. Moreover, evidence of cellular antioxidant activity and correlated specific genomic events induced by coffee components, which are relevant to antioxidant function in both animal and human studies, will be discussed.
67. 67
  Hwang, H. S.; Winkler-Moser, J. K.; Kim, Y.; Liu, S. X. Antioxidant Activity of Spent Coffee Ground Extracts Toward Soybean Oil and Fish Oil. Eur. J. Lipid Sci. Technol. 2019, 121, 1800372, DOI: 10.1002/ejlt.201800372
  There is no corresponding record for this reference.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jafc.2c07365.
- Detailed unbound and covalently bound phenolic compounds of coffee fractions; microscopic pictures of WPI-stabilized emulsions with HMWF added to the continuous phase; droplet size distribution of WPI-stabilized emulsions with different fractions added to the continuous phase; microscopic pictures of WPI-stabilized emulsions with different fractions added to the continuous phase; and zeta-potential of WPI-stabilized emulsions with different fractions added to the continuous phase (PDF)
- jf2c07365_si_001.pdf (398.86 kb)
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Physical and Oxidative Stabilization of Oil-In-Water Emulsions by Roasted Coffee Fractions: Interface- and Continuous Phase-Related EffectsClick to copy article linkArticle link copied!

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1. Introduction

2. Materials and Methods

2.1. Materials

2.2. Preparation of Coffee Brew

2.3. Isolation of HMWF, LMWF, and Non-Defatted HMWF from Coffee Brew

2.4. Carbohydrate, Protein, and Phenolic Group Contents

2.5. Analysis of Unbound Phenolic Compounds by Liquid Chromatography Coupled with Diode Array Detection and Mass Spectrometry

2.6. Analysis of Covalently Bound Phenolic Compounds

2.7. Interfacial Activity

2.8. Antioxidant Properties

2.9. Emulsion Preparation

2.10. Physical Properties of Emulsions

2.11. Lipid Oxidation

2.12. Statistical Analysis

3. Results and Discussion

3.1. Characterization of Coffee Fractions

3.1.1. Chemical Composition

3.1.2. Interfacial Activity

Figure 1

3.2. Coffee Fractions at the Interface of Emulsions

3.2.1. Physical Properties of Emulsions

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3.2.2. Antioxidant Activity of Coffee Fractions

Figure 5

3.2.3. Lipid Oxidation in Emulsions

Figure 6

3.3. Added Coffee Materials to the Continuous Phase of Emulsions

3.3.1. Influence of HMWF Concentrations on the Stability of Emulsions

Figure 7

Figure 8

Figure 9

3.3.2. Influence of Coffee Fractions on the Stability of Emulsions

Figure 10

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Physical and Oxidative Stabilization of Oil-In-Water Emulsions by Roasted Coffee Fractions: Interface- and Continuous Phase-Related Effects
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