The betacyanin pigments from 21 genotypes of 7 Amaranthus species were separated by gel filtration chromatography and HPLC. On the basis of their IR and UV−visible spectra, enzymatic hydrolysis, and chromatographic profiles, the pigments were identified as homogeneous betacyanins, which consisted on average of 80.9% amaranthine and 19.2% isoamaranthine. Dried crude betacyanin extracts contained 23.2−31.7% protein, and the purified sample retained 12.8% protein. The betacyanins were difficult to separate from protein. Total betacyanins in the Amaranthus species ranged from 46.1 to 199 mg/100 g of fresh plant material and from 15.4 to 46.9 mg/g of dry extracts. The mean extraction rate of the eight best genotypes was 2.18%. Amaranthus cultivated species contained much more betacyanin than wild species and had much higher biomass, indicating that certain cultivated genotypes had greater potential for commercial development as natural colorant sources. Dried extracts from Amaranthus species may form natural nutritive pigments for the food industry.

Keywords: Amaranthus; betacyanins; pigments; amaranthine; isoamaranthine; colorants

Three strains of the mushroom Agrocybe cylindracea (strains B, M, and W) are commercially available. Strain W contained higher moisture content (91.50%) than strains B and M (90.35 and 90.34%, respectively). A. cylindracea strains were low in fat (2.18−2.71% dry weight) and high in fiber (16.15−16.70%) and protein contents (34.17−44.94%). Fructose, mannitol, and trehalose were detected in all three strains, whereas glucose was not detected in strain B. Strain W contained the highest amount of total free amino acids (63.34 mg/g of dry weight), and strain M contained the lowest (39.30 mg/g). The three strains contained high amounts of glutamic acid, threonine, arginine, and phenylalanine, with glutamic acid being the most significant. The contents of monosodium glutamate-like components, including aspartic and glutamic acids, were similar in three strains. Strain B contained the highest amounts of total 5‘-nucleotides and flavor 5‘-guanosine monophosphate (1.51 and 0.63 mg/g), whereas strain W contained the lowest (0.67 and 0.21 mg/g, respectively). In this study, the three strains were considerably different in both their proximate compositions and taste components and their physical appearances.

Keywords: Agrocybe cylindracea; mushrooms; proximate composition; soluble sugars; free amino acids; 5‘-nucleotides

The components responsible for chile hot flavor, capsaicinoids, are synthesized through the cinnamic acid pathway, and their degradation is thought to be aided by the action of peroxidases. This work describes the evolution of capsaicinoids during the development, maturation, and senescence of the fruit in three varieties of hot chile peppers widely used in Mexico [Habañero (Capsicum chinense Jacq.), De árbol (C. annuum var. Annuum), and Piquin (C. annuum var. Aviculare)] and its relation with the activity of peroxidases in these fruits. Capsaicinoids were more abundant in the fruit of Habañero, followed by De árbol and then by Piquin. Capsaicin was higher than dihydrocapsaicin in the three varieties. Capsaicinoids, capsaicin, and dihydrocapsaicin increased continuously and reached a peak after 45−50 days from fruit set (DFFS) in Habañero and De arobol and after 40 DFFS in Piquin and then declined. Peroxidase activity increased at the time when the concentration of capsaicinoids started to decrease. There was an inverse relationship between the evolution of capsaicinoids and peroxidase activity that might indicate that this enzyme is involved in capsaicinoid degradation.

Keywords: Capsicum annuum; C. chinense; capsaicin; dihydrocapsaicin; postharvest; Habañero; De árbol; Piquin

The effect of progressive succinylation upon the conformation of faba bean legumin has been studied using chemical analysis, viscometry, analytical ultracentrifugation, UV and fluorescence spectroscopy, and differential scanning calorimetry (DSC). The protein dissociates gradually into 3 S subunits forming a 7 S intermediate. DSC measurements revealed a continuous loosening of the spacial structure with increasing degree of succinylation. Viscometric and spectroscopic studies indicate the presence of a particular conformational state at 60−80% succinylation, whereas a largely expanded structure was shown to exist in exhaustively succinylated legumin due to a cumulative effect of N- and O-succinylation.

Keywords: Legumin; faba bean protein; succinylation; conformational changes

Adipic acid behavior was studied as a cross-linkage agent for Canavalia ensiformis native starch. A 2³ factorial design with two replicates of each treatment was utilized. Acid concentration (1 and 2%) and the chemical agent incorporation method (direct incorporation with an initial pH adjustment, direct addition with pH readjustment, and 3% NaOH simultaneous addition) were the factors utilized. Gel firmness and syneresis were used as response variables. Main factors and their interactions showed statistical influence (P < 0.05) over the cross-linkage level achieved; the most effective modification was obtained by reactant direct incorporation. Cross-linkage increased gel firmness (11.25 mm penetration) compared to native starch (14.75 mm penetration), diminished syneresis to 7.15 mL/50 mL, and reduced solubilization and swelling power to 18% and 28.04 g/g levels, respectively.

Keywords: Cross-linked; starch; Canavalia ensiformis; adipic acid; functional properties

Residual levels of the pesticide azinphos-ethyl were studied in an experiment on field-sprayed Grand-Smith apples. The pesticide was applied according to manufacturer recommendations. Apples received a single spraying at a rate of application of 60 g of active ingredient/100 L. Residues were determined with a simple gas chromatographic method using a 30 m glass capillary column and an NP detector. The recovery of azinphos-ethyl was 87−123%, and the limit of determination was 0.005 mg/kg. The decomposition of azinphos-ethyl was studied in apples remaining on the trees after spraying and in apples harvested and stored under ambient temperature conditions, in refrigerated rooms, and in controlled atmosphere (CA) rooms. The results show that there exists a delayed residue decline during postharvest storage compared to that for apples remaining on the trees. From the experimental results, best fit curves were determined and kinetic equations, rate constants, and half-lives were calculated. Half-lives and times to reach the legal limit (0.05 mg/kg) were, respectively, 10 and 62 days for apples on the trees, 83 and 447 days for apples stored at ambient conditions, 91 and 507 days for apples stored in CA rooms, and 136 and 749 days for apples stored in refrigerated rooms.

Keywords: Azinphos-ethyl; insecticide residues; degradation; apples

As part of an effort to define the biological roles of carbohydrate groups of the tomato glycoalkaloid α-tomatine in plants and animals, experiments were carried out to optimize the acid hydrolysis of the tetrasaccharide side chain of α-tomatine to products with three, two, one, and zero sugar groups. This was accomplished by following the time course for hydrolysis in 1 N HCl at 100 °C, isolating the hydrolysis products by chromatography on an aluminum oxide column, and determining the number and nature of hydrolysis products, including free sugars, with the aid of thin-layer chromatography and gas chromatography/mass spectrometry of alditol acetate sugar derivatives. The results show that a 20-min hydrolysis time appears useful for the formation of a mixture of the monosaccharide δ-tomatine, the disaccharide γ-tomatine, and the trisaccharide β₁-tomatine. Efforts to isolate the other possible trisaccharide, β₂-tomatine, were unsuccessful, apparently because xylose is degraded during the hydrolysis. A 70-min exposure achieved complete hydrolysis of α-tomatine to the aglycon tomatidine. α-Tomatine was stable to hydrolysis at 37 °C, suggesting that it may also be stable to comparable acid conditions of the gut of insects, animals, and humans. The approach used should be generally useful for preparing hydrolysis products of glycoalkaloids and other glycosides such as saponins to facilitate assessing the role of the carbohydrate groups of these compounds in host-plant resistance, nutrition, and microbiology.

Keywords: Acid hydrolysis; aluminum oxide chromatography; carbohydrate analysis; gas chromatography; glycoalkaloids; glycoside; mass spectrometry; thin-layer chromatography; tomatidine; α-tomatine; β₁-tomatine; β₂-tomatine; γ-tomatine; δ-tomatine; tomatoes

Fruit firmness, free polyamine levels (putrescine, spermidine, and spermine), abscisic acid (ABA), and color index were determined in lemon fruit at two ripening stages (at color break and fully yellow) after vacuum infiltration with 1mM putrescine and 1 mM calcium chloride. Both treatments significantly increased fruit firmness as compared with control fruit in stage 1 lemons. Putrescine-treated fruits showed higher levels of firmness and lower weight loss than calcium-treated or nontreated fruits during storage. The concentrations of putrescine, spermidine, and spermine were higher in stage 1 than in stage 2 lemons, whereas the opposite was found for ABA. The treatment with putrescine was the most effective to maintain higher levels of endogenous putrescine and spermidine, but only for stage 2 fruit. Both putrescine and calcium treatments delayed the color change, which was related to the lowest levels of ABA found.

Keywords: Lemon; Citrus lemon; polyamines; abscisic acid; postharvest; firmness; color

Hard-to-cook (HTC) is a textural defect that affects legume seeds stored in adverse conditions. Phenolic acids were extracted from dehulled soft (control) and HTC beans. HPLC analyses of the phenolic fractions indicated the presence of caffeic, p-coumaric, sinapic, and ferulic acids. The highest content of phenolic acids was present as methanol-soluble esters in the control samples (approximately 45 times more than in HTC). Phenolic acids bound to the water-soluble pectin fraction were 2 times higher in HTC than in control beans, wheras the content of ferulic acid bound to the water-insoluble residue of the cell walls was 4 times higher in the control than in HTC samples. Through Fourier transform infrared spectroscopy accumulation of pectates and binding of phenolics to cell wall components were detected in HTC samples.

Keywords: Beans; common beans; Phaseolus vulgaris; HTC; hard-to-cook; phenolics

Volatile compounds present in cucumbers fermented in 2% salt were analyzed using purge and trap concentration followed by GC-MS. Thirty-seven volatile compounds were identified from over 100 peaks detected using GC-MS. Most of the identified compounds did not change during fermentation. However, the ability of disrupted cucumber tissue to produce (E,Z)-2,6-nonadienal and 2-nonenal, the two most important volatiles in fresh cucumber odor, decreased during fermentation. In addition, linalool increased to levels several times its odor threshold during the first 10 days of fermentation.

Keywords: Cucumis sativus; gas chromatography; mass spectrometry; Lactobacillus plantarum; Cucurbitaceae

A possible way to valorize citrus peels and seeds, which are byproducts of the juice extraction industry, is to use them as natural antioxidants. The antioxidant activity of several citrus peel and seed extracts obtained either by methanol extraction (free phenolic compounds) or by alkaline hydrolysis (bound phenolic compounds) was tested in a model system based on accelerated citronellal oxidation. Generally, seeds possessed greater antioxidant activity than peels. The composition of all tested samples was studied by HPLC:  methanol extracts are rich in flavones and glycosylated flavanones, whereas hydrolyzed extracts contain mainly phenolic acids and flavonols. The phenolic composition of some citrus peels and seeds was described for the first time. No clear relationship could be shown between the antioxidant activity and the phenolic composition of the extracts.

Keywords: Citrus fruits; byproducts; antioxidant activity; flavanones; phenolic acids

A high molecular weight protein fraction (peak I) obtained from peanut (Arachis hypogaea L. cv. Florunner) seed was fractionated using ammonium sulfate and methanol to isolate the protein(s) involved in off-flavor volatile production during roasting of peanut. The results showed that maximum off-flavor volatile-producing activity is associated with the 20% ammonium sulfate precipitate and 85% methanol-soluble fraction of this protein. Peak I protein was found to be lipoprotein in nature and is rich in oleic acid (63%) and palmetic acid (8%). Furthermore, the 85% methanol-soluble fraction of peak I protein was found to contain a mixture of low molecular weight proteins and major amounts of glycine (11%), alanine (11%), proline (15%), phenylalanine (8%), and lysine (8%).

Keywords: Amino acids; electrophoresis; fatty acids; fractionation; lipoprotein; off-flavor; peanut; protein

A bicomponent polymerization model for heat-induced protein denaturation and viscosity changes in milk is presented. The model recognizes denaturation kinetics of β-lactoglobulin (β-lg) and the association between denatured β-lg and casein micelles. The aim of the study was to develop a mathematical model based on physical and chemical fundamentals for prediction of the rheology of milk products during thermal processes. The model reproduces both the degrees of denaturation of β-lg and the viscosity change of skim milk heated at temperatures between 80 and 120 °C very well. In contrast to the volume fraction model of Snoeren, the polymerization model accounts for higher viscosities of milk heated at a higher temperature at the same denaturation degree of β-lg. This confirms that, in addition to heat load, heating rate and temperature contribute to the rheological properties of dairy products. The model developed will be a basis for future research in describing the relation between process variables and the functional properties of milk products.

Keywords: Denaturation; viscosity; rheological properties; polymerization model

The effects of tea (Camellia sinensis L.) of three types on excessive free radicals were examined utilizing spin trapping, 1,1-diphenyl-2-picrylhydrazyl radical, lipid peroxidation, and lactate dehydrogenase leakage from cultured cells. Green tea extract presented significant antiradical effects in these four assay systems, whereas oolong tea and black tea extracts showed a rather weak protective effect against free radicals. A more potent scavenger effect using cultured cells was found with a green tea tannin mixture. Similarly to the effects of the green tea tannin mixture, (−)-epigallocatechin 3-O-gallate, its main ingredient, had an inhibitory effect on oxidative stress-induced apoptosis. The activities of the antioxidation enzymes in rats after subtotal nephrectomy were increased, suggesting a protective action against oxidative stress. The increased levels of uremic toxins in the blood were also reduced in rats given (−)-epigallocatechin 3-O-gallate. These findings indicate that (−)-epigallocatechin 3-O-gallate helps to inhibit the progression of renal failure by scavenging radicals.

Keywords: Tea; (−)-epigallocatechin 3-O-gallate; free radical; hydroxyl radical; apoptosis; DNA fragmentation; renal epithelial cell; nephrectomy

The texture of fish eggs changes into a unique chewy texture, for example, caviar, during preservation in salt solution. In this work, the changes in fish eggs after preservation in salt solution were investigated. After salt preservation, fish eggs stiffened, and an increase of ε-(γ-glutamyl)lysine (GL) cross-linked products in the chorion fraction was observed. Transglutaminase (TGase) also activated after salt preservation. Therefore, it can be hypothesized that the change of breaking strength after salt preservation was due to the increment of the GL cross-linked products, which was produced by the activation of TGase. Additionally, two kinds of TGase isoforms localized in the chorion fraction of fish egg.

Keywords: Transglutaminase; chorion; hardening; fish egg; salt preservation

The adsorption properties of cholesterol-reduced egg yolk low-density lipoprotein (CR-LDL) at oil-in-water interfaces were studied. The CR-LDL was prepared by absorbing cholesterol to β-cyclodextrin (CD). The CR-LDL formed larger emulsion particles at low protein concentration. Concentration of protein at the interface was greater for emulsions made by CR-LDL when compared to the control LDL at pH 7.0 and 3.5, a result attributed to formation of lipoprotein aggregates by removing the cholesterol in LDL. The emulsion stability of CR-LDL at low protein concentration was lower at pH 7.0 than at pH 3.5, whereas the LDL emulsions showed considerable stability during aging for 1 month. Electrophoretic analysis of the adsorbed polypeptides revealed the preferential adsorption of LDL polypeptides at the interface. Increase in protein concentration resulted in higher phosphatidylethanolamine (PE) and lower phosphatidylcholine (PC) levels at the interface, whereas the opposite trend was observed at pH 3.5. Time-dependent polymerization of lipoproteins through hydrophobic interaction at the interface was detected by SDS−PAGE analysis. Removing the cholesterol from egg yolk LDL caused changes in phospholipid−protein interactions at the interface, which could be explained the instability of CR-LDL emulsion.

Keywords: Egg yolk; low-density lipoprotein; cholesterol; β-cyclodextrin; emulsion; stability; phospholipids

Structural and functional features were studied on the native dimeric form of β-lactoglobulin at neutral pH and on the monomeric forms obtained either by raising the pH to 9.0 or by blocking the thiol group of Cys121 with iodoacetamide under bland dissociating conditions. The thiol blocked monomer did not reassociate to native-like dimers, it retained retinol-binding ability, and it was found to display many of the structural features of the monomer obtained at pH 9, but differed in several structural features from the native dimer. The supramolecular associative properties of the proteins were studied by measuring concentration dependence of the accessibility of the backbone exchangeable amide protons in ¹H NMR H/D exchange experiments, of their ligand-binding properties, and of their intrinsic fluorescence features. Evidence of reversible association was found for all the proteins with a very similar concentration dependence, indicating that the weak forces involved in this association were different from those stabilizing the native dimer.

Keywords: β-Lactoglobulin; sulfhydryl groups; association equilibrium; ligand-binding properties

Insoluble elastin was rendered soluble by pepsin digestion and HCl treatment. The antioxidative activity of pepsin-solubilized elastin (PSE) and acid-solubilized elastin (ASE) was investigated. The peroxide value and carbonyl value of oleic acid in the presence and absence of PSE and ASE after oxidation at high temperature (75−90 °C) were evaluated. Both PSE and ASE were effective inhibitors of the oxidation of oleic acid. The antioxidative activity of PSE and ASE was enhanced in the presence of citric acid as a synergist. Both PSE and ASE are thought to be valuable as antioxidants. Since the preparation of ASE was easier than the preparation of PSE, ASE could therefore be more useful as an antioxidative agent. The antioxidative activity of low molecular weight peptides obtained from ASE could be found by the ferric thiocyanate method.

Keywords: Elastin; antioxidant; antioxidative peptide

A sensitive and reproducible HPLC assay with fluorometric detection was used to measure the malondialdehyde (MDA) concentration in food (butter, margarine, oil, fish, and meat tissue). Samples were homogenized in water supplemented with butylated hydroxytoluene. Proteins were precipitated with ice-cold 5% trichloroacetic acid and removed by centrifugation. The supernatant was incubated in a 0.28% thiobarbituric acid (TBA) mixture from which the oxygen was depleted. Optimal incubation time and temperature, for the TBA treatment, were found to be 30 min and 90 °C, respectively. The MDA−TBA adduct was fractionated by reverse phase HPLC and detected by fluorescence (λ_EX = 515 nm; λ_EM = 543 nm). Elution was performed at 1 mL/min flow rate with a mixture of acetonitrile and sodium phosphate at pH 7 (15:85 v/v). The described sample preparation procedure minimizes the lipid oxidation and provides high sensitivity (0.01 pmol of MDA), reproducibility, and specificity.

Keywords: Malondialdehyde; food; lipid peroxidation; HPLC

The surface dynamic properties (surface tension and surface dilational properties) of films formed by bovine serum albumin (BSA) and the surfactant Tween 20 were studied using periodic sinusoidal interfacial compression and expansion in a superficial rheometer (ring trough). All measurements were performed at a constant temperature (20 °C) and at constant BSA concentration in the bulk phase (0.1% w/w). The surface dynamic properties were dependent on the protein/surfactant ratio in the bulk phase, on the interfacial composition (BSA, Tween 20, and BSA−Tween 20 mixture), and on the aqueous phase composition (i.e., presence of ethanol and sucrose). The results show that at higher protein concentrations in mixed films the surface dilational modulus is higher, which agrees with greater protein−protein interactions. However, lower superficial dilational modulus was observed at higher surfactant concentrations, which agrees with weaker surfactant−surfactant interactions. The dynamic surface tension and surface dilational modulus depend on subphase composition. The surface dynamic properties were tested by a kinetic model to monitor the unfolding and rearrangements of adsorbed BSA molecules including the existence of BSA−Tween 20 interactions.

Keywords: Superficial dilational rheology; adsorption; surface properties; bovine serum albumin; Tween 20

Concentrated pineapple juice reconstituted to 12 °Brix was used to obtain three types of clarified juices by ultrafiltration (UF) and microfiltration (MF) systems with polysulfone and ceramic membranes. They were evaluated by physicochemical analysis, in comparison to the reconstituted juice control, as well as through the sensorial evaluation of the soft drinks obtained by them. The best volume recovery was observed with 50 000 Da polysulfone membranes. Best components recovery was obtained with the 0.22 μm ceramic membrane. The 50 000 Da polysulfone membrane presented better efficiency to remove tannins and pectin. Both membranes of 50,000 D cutoff presented the same performance to decrease turbidity. The 0.22 μm ceramic membrane presented the best overall performance. Clarified juice flow rate was highest in the juice obtained using the 0.22 μm ceramic membrane (52.02 L m^-2 h^-1). The three soft drinks formulated from the clarified pineapple juices presented no differences, at a significance level of 5%.

Keywords: Pineapple juice; pineapple soft drink; ultrafiltration; microfiltration; physicochemical and sensory evaluation; Ananas comosus

Several herbicides commonly used on soybeans are often difficult to extract, isolate, and quantify from the complex soybean matrix at low concentrations. Typical analytical methods for herbicide residues in soybeans are single analyte procedures using HPLC or GC after chemical derivatization. In this study, method development for the analysis of six polar herbicides in soybeans was performed using pressurized liquid extraction (PLE), which is also known by the trade name, Accelerated Solvent Extraction, and capillary electrophoresis (CE). In CE, a 50 mM ammonium acetate running buffer, pH 4.75, was able to separate imazaquin (Scepter), chlorimuron-ethyl (Classic), thifensulfuron-methyl (Harmony), acifluorfen (Blazer), bentazon (Basagran), and 2,4-dichlorophenoxyacetic acid in a 75 μm i.d., 83 cm capillary (65 cm to detector) within 30 min at 17 kV applied voltage. Chlorsulfuron (Glean) was used as an internal standard in the analysis, and detection was by UV absorbance at 240 nm in a high-sensitivity optical cell. PLE extracts required extensive cleanup prior to CE/UV analysis. Several cleanup techniques were investigated and compared, including liquid−liquid partitioning, gel-permeation chromatography, semipreparative HPLC, and solid-phase extraction with a variety of stationary and mobile phase combinations. A combination of techniques that provided the most efficient cleanup was selected in the final method. Four of the six herbicides could be determined by the method in samples fortified at tolerance levels with average recoveries of 71% and relative standard deviation (RSD) of 11%. At a higher spiking level, all of the herbicide recoveries were >70% with %RSDs < 10%, except for acifluorfen which gave more variable recoveries.

Keywords: Residue analysis; herbicides; soybeans; capillary electrophoresis; pressurized liquid extraction

A methodology for measuring the natural deuterium distribution in citric acid by the SNIF-NMR method is presented. Triethyl citrate (TEC) is retained as a molecular probe for ²H NMR. The method provides efficient criteria for characterizing the authenticity of lemon juices:  it is a powerful approach to detect the addition of exogenous citric acid manufactured from beet sugar (or other C3 plants). The whole analytical chain includes the separation and purification of citric acid from lemon juices or concentrates via preparative HPLC, followed by the synthesis of TEC. The present procedure may also integrate a determination of the ¹³C contents of sugars, citric acid, and l-malic acid. The correlation between δ¹³C values of sugars and of both acids is very specific and reinforces the discriminating power of the SNIF-NMR method.

Keywords: Citric acid; triethyl citrate; SNIF-NMR; malic acid; sugars; lemon juices; lemon concentrates; δ¹³C profile; preparative HPLC; adulteration; authentication

A multiresidue procedure for the insecticides used by organic farmers has been developed. Rotenone, cevadine, and veratridine (the major components of sabadilla), pyrethrin I and pyrethrin II (the major components of pyrethrum), and ryanodine and dehydroryanodine (the major components of ryania) can be separated by high-performance liquid chromatography (HPLC) and detected and quantified by atmospheric pressure chemical ionization mass spectrometry (APCI/MS) in the selected ion monitoring mode. Piperonyl butoxide, a material sometimes used together with rotenone or pyrethrum to enhance toxicity, can also be detected and quantified by this procedure. The analytes are extracted with acetonitrile/water and are cleaned up with a C₁₈ solid-phase extraction cartridge. Rotenone, piperonyl butoxide, and the two major sabadilla components could be detected (signal-to-noise ratio = 10) in lettuce, cucumber, and cabbage at 1−6 ppb. Pyrethrin I and the ryania components could be detected between 10 and 171 ppb in these vegetables, whereas pyrethrin II was generally less sensitive, with a limit of detection as high as 200 ppb in cabbage. Recoveries were in the 72−124% range. Percent coefficients of variation ranged from 2 to 17.

Keywords: Organic farming; sabadilla; veratridine; cevadine; ryania; dehydroryanodine; ryanodine; rotenone; pyrethrum; pyrethrin I; pyrethrin II; piperonyl butoxide; high-performance liquid chromatography (HPLC); atmospheric pressure chemical ionization liquid chromatography mass spectrometry (APCI/LCMS)

A competitive enzyme-linked immunosorbent assay (ELISA) was developed for the quantitative detection of fenpropathrin [(RS)-α-cyano-3-phenoxybenzyl-2,2,3,3-tetramethylcyclopropanecarboxylate]. Polyclonal antisera were isolated from rabbits immunized with two different fenpropathrin hapten conjugates. One hapten contained an amino function; the other contained a carboxyl group for conjugation to carrier proteins. Mollusk hemocyanins, thyroglobulin, and fetuin were used as carrier proteins. The antisera varied greatly in their affinities for fenpropathrin. A homologous assay system using the coating antigen format was the most sensitive. The IC₅₀ for fenpropathrin was 20 μg/L, and the lower detection limit was 2.5 μg/L. Pyrethroids, such as phenothrin, permethrin, resmethrin, fenvalerate, deltamethrin, cyfluthrin, and cypermethrin, and the pyrethroid metabolites, 3-phenoxybenzoic acid and fenpropathrin acid, did not cross-react significantly in this assay. Ten percent acetone or methanol and a pH of 4 were determined to be optimum assay conditions. Various cationic, anionic, and nonionic detergents had no significant effect on the assay.

Keywords: Fenpropathrin; pyrethroid; ELISA; pesticide; enzyme immunoassay; cross-reactivity

Evaluation of chain lengths of polymeric phosphates is essential for the characterization of polyphosphate-based fertilizers. The titrimetric method, which is the most reliable and simple means of determining number average chain lengths (n̄), cannot be applied to solutions containing micronutrient ions. In this investigation, methods have been proposed for the elimination of metal ion interference prior to the titrimetric determination of the average chain length of polyphosphate solutions. When Cu²⁺, Fe³⁺, Mn²⁺, Mg²⁺, or Mo⁶⁺ are present in the solutions, solvent extraction of their complexes with 8-hydroxyquinoline at appropriate pH, prior to titration, was very effective. The interference due to Zn²⁺ was conveniently masked by the addition of potassium ferrocyanide and the titration carried out in the presence of the insoluble complexes. These methods do not introduce any perceptible additional error in the determination of n̄. They can also be conveniently combined when more than one interfering ion is present in the polyphosphate solution. These methods, therefore, offer a rapid, simple, and reliable means for analyzing micronutrient polyphosphate fertilizers.

Keywords: Polyphosphate titration; chain length; analysis; interference; metal ions

Many papers have been published during the past 15 years on suitable methodologies for the analysis of cholesterol oxidation products (COPs) in foodstuff. Regarding milk powders, data found in the literature are difficult to compare, if not contradictory. Therefore, the aim of the present study was to compare four of the most frequently used methods for COP analysis to identify the best. A method with direct saponification of the sample was compared with three methods involving preliminary fat extraction (Folch's, Radin's, and Maxwell's methods). After saponification all of the samples were enriched by solid-phase extraction (SPE) on aminopropyl cartridges and analyzed by GC-MS. [²H₆]cholesterol was used to monitor artifact formation. The four methods were applied to the analysis of three milk powders containing different levels of COPs (low, medium, and high contents). The method offering the best compromise was found to be direct saponification of the milk powder, without preliminary fat extraction, followed by aminopropyl-SPE and GC-MS quantification.

Keywords: Milk powder; cholesterol; oxidation; artifacts; GC-MS; validation

To elucidate the effect of lignin structure on the properties of lignin−starch composites, an industrial pine kraft lignin sample was fractionated by sequential extraction with organic solvents. Three fractions were obtained with different carbohydrate contents, infrared spectra, and molecular size distributions. In addition, an in-depth structural investigation was performed by GC−MS analyses of the low-molecular weight phenolics occurring in the native fractions or obtained by thioacidolysis. The properties of the lignin−starch composites made from pine kraft lignin or its fractions were evaluated, as compared to reference starch films. Although present in small quantities, the low-molecular weight fraction isolated from pine kraft lignin was observed to have a key role in the mechanical properties of the films, mainly as a starch plasticizer.

Keywords: Lignin; starch; lignin utilization; lignin−starch composites

The effect of dietary fiber and polyunsaturated fatty acids on the excretion of an ingested stable, lipophilic environmental pollutant was investigated in nonpregnant and pregnant rats fed hexachlorobenzene (HCB) diet (10 μg/100 g of diet). Nonpregnant rats ingesting guar gum, with polyunsaturated fatty acid for 4 weeks after an HCB diet period for 2 weeks, had lower perirenal fat mass as well as total amount of HCB found in such fat compared with cellulose-ingesting groups (P < 0.05). A large proportion of HCB in dams disappeared from the dams during the 15-day lactation period and was transferred to their suckling pups through the milk in both dietary fiber groups. No significant difference in total amount of HCB in suckling pups was observed whether the dams ingested cellulose or guar gum diet during the lactation period. It was concluded that the excretion of HCB into milk was so rapid that the guar gum-induced acceleration of its excretion from the dams were masked.

Keywords: Hexachlorobenzene; dietary fiber; lactation; suckling pups; milk

The previously reported [Pearson, T. Lebensm. Wiss. -Technol. 1996, 28 (6), 203−209] channel image sorter has been used to re-sort color-sort and hand-sort rejects and to sort mainstream (pre-hand-sort) U.S. pistachios. Sorting was carried out at commercial speeds of up to 163 kg/channel/h. Recoveries of good nuts of 39−67% on re-sorted product and 97.8% on mainstream nuts were achieved. Aflatoxin levels were reduced from 8.6−4.8 to 0.04−2.5 ng/g on color-sort rejects and to 15 from 22 ng/g on hand-sort rejects. For mainstream product, aflatoxin levels were reduced from 0.12 to 0 ng/g by image sorting, compared to reduction to 0.04 ng/g by hand sorting. Quality for mainstream sorting improved significantly, particularly for other damage, serious insect damage, gross defects, and loose kernels. Re-sort quality improved as well, but recovered product will still require dyeing. The sorter should find application in product recovery, in preparation of product for very stringent markets [Schatzki, T. F. J. Agric. Food Chem. 1998, 46 (1), 2−4], and in presorting the very large samples required for testing lots with high reliability, that is, low standard error of the mean [Schatzki, T. F. J. Agric. Food Chem. 1998, 46 (1), 2−4].

Keywords: Sorting; pistachios; aflatoxin; quality

A series of in vivo and in vitro experiments was conducted to determine the available energy of a bulking agent, Fibersol 2 (FS-2). Fibersol 2 is obtained by a combination of heat and enzyme treatments of cornstarch to produce a low-viscosity, low-digestible dextrin with an average molecular massweight of 2000 Da. Although the substance is of the type known in Japan as an indigestible dextrin, it also comes within the U.S. Food and Drug Administration's (FDA) definition of “maltodextrin” as found in the FDA Generally Recognized as Safe (GRAS) affirmation regulations. Chemical analysis shows FS-2 to contain glucopyranosyl units with 1,6-anhydro-β-d-glucose (levoglucosan) at some of the reducing terminals. Linkages in the molecule are randomly distributed among units consisting of α- and β-(1→4), (1→6), (1→2), and (1→3) glycosidic bonds. In vitro digestion of FS-2 with successive treatments of salivary α-amylase, a gastric juice preparation, pancreatic α-amylase, and intestinal mucosal enzymes gave 89.8% recovery of the starting material. Rats gavaged with FS-2 were found to have only a 5% increase in plasma glucose concentrations over 120 min compared to rats administered an equal amount of glucose. Approximately 38% of FS-2 administered to rats by gavage is recovered in the feces. Growth rates of rats fed FS-2 indicate less than <10% of the dextrin is contributing net metabolizable energy. FS-2 has an energy value of 2.2 kJ/g.

Keywords: Dextrin; maltodextrin; bulking agent; energy and; rats

The Maillard-type volatile compounds obtained from the reaction of glutathione and glucose were mainly furans, carbonyl compounds, and sulfur-containing compounds including thiophenes, thiazoles, and cyclic polysulfides. Both pH 8.0 and 6.0 were favorable conditions for sulfur-containing compound formation, whereas acidic conditions were favorable for furan and derivative formation. The reaction between glutathionesulfonic acid, an oxidized form of glutathione, and glucose primarily produced furans, carbonyl compounds, pyrazines, and pyrroles. Furans dominated the products obtained from the reactions at pH 6.0 and 8.0. Pyrazines increased as the reaction pH increased. The disappearance of sulfur-containing compounds in the products of glutathionesulfonic acid and glucose reaction systems indicated glutathionesulfonic acid could not provide hydrogen sulfide for the reaction.

Keywords: Glutathione; glutathionesulfonic acid; sulfur-containing; oxidation; pH

[1-¹³C]-d-Fructose and [U-¹³C₆]-d-fructose were applied to detached ripening strawberry fruits, and the incorporation into 2,5-dimethyl-4-hydroxy-3(2H)-furanone 1, 2,5-dimethyl-4-methoxy-3(2H)-furanone 2, 2,5-dimethyl-4-acetoxy-3(2H)-furanone 3, 2,5-dimethyl-4-hydroxy-3(2H)-furanone β-d-glucopyranoside 4, and 2,5-dimethyl-4-hydroxy-3(2H)-furanone 6‘-O-malonyl β-d-glucopyranoside 5 was determined by HRGC−MS and HPLC−ESI MS−MS. The data clearly showed the direct conversion of d-fructose to the furanones without cleavage of the carbohydrate prior to the formation of 1−5, as expected for a biological Maillard reaction. Both, the furanone and the d-glucose moiety of 4 and 5 contained the labels. However, the label was primarily incorporated into the furanone moiety, indicating that d-fructose is a more efficient precursor of the furanones than d-glucose.

Keywords: 2,5-Dimethyl-4-hydroxy-3(2H)-furanone; biosynthesis; stable isotope ratio analysis; biological Maillard reaction; Fragaria ananassa

On the basis of labeling experiments with [¹³C]₆-glucose/unlabeled proline as well as quantitative data obtained in model studies using stable isotope dilution assays, 1-pyrroline and hydroxy-2-propanone were identified as effective intermediates in generating the roast-smelling food odorant 2-acetyltetrahydropyridine (ATHP; two tautomers). Synthesis of the key precursor compound, 2-(1-hydroxy-2-oxo-propyl)pyrrolidine, and studies on its degradation confirmed the important role of this intermediate in ATHP formation. Boiling of the intermediate for 30 min in aqueous solution generated >30% of ATHP on a molar basis. 1-Pyrroline and 2-oxopropanal were confirmed as important intermediates in the generation of the further roast food odorant, 2-acetyl-1-pyrroline (AP). On the basis of results of labeling experiments with [¹³C]₆-glucose/unlabeled proline, two different mechanisms could be proposed. One leads to AP via 2-(1,2-dioxopropyl)pyrrolidine as the precursor with elimination of the aldehyde group in 2-oxopropanal as carbon dioxide. The other one suggests elimination of carbon-2 of the pyrroline ring. The latter mechanism was further established by a result showing that from the reaction of 2-methyl-1-pyrroline with 2-oxopropanal AP was also generated.

Keywords: 1-Pyrroline; 2-oxopropanal; hydroxy-2-propanone; 2-acetyl-1-pyrroline; 2-acetyltetrahydropyridine; 2-acetyl-3-methyl-3,4,5,6-tetrahydropyridine; 2-(1-hydroxy-2-oxo-1-propyl)pyrrolidine

Two new synthetic pathways toward the new Maillard flavor compound 5-acetyl-2,3-dihydro-1,4-thiazine are disclosed. 1-Bromo-3,3-dimethoxy-2-butanone and N-protected 2-mercaptoethylamine are the key components in both synthetic routes. The first approach involves a one-step synthesis via nucleophilic substitution, followed by cyclization and hydrolysis. The second route entails a nucleophilic substitution, followed by TFA-deprotection of the primary amino function, which led to a spontaneous intramolecular transimination and hydrolysis of the acetal moiety to afford the desired flavor compound in very good yield.

Keywords: Popcorn flavor; roasty flavor; 5-acetyl-2,3-dihydro-1,4-thiazine; Maillard; flavor compound

Volatile compounds from lychee (Litchi chinesis Sonn.), a tropical fruit native to China, were extracted using both Freon 113 and ethyl acetate solvents. The odor-active compounds present in the fruit were isolated and characterized using gas chromatography/olfactory (GC/O), chromatography, and mass spectrometry. Authentic standards were used to determine mass spectral, retention index, and odor match. GC/O analysis detected at least 60 odor-active volatiles in the fruit extract. More odor-active volatiles were detected in the ethyl acetate extract than in the nonpolar Freon extract. Among the compounds that had significant odor activity, geraniol, guaiacol, vanillin, 2-acetyl-2-thiazoline, 2-phenylethanol, unknown (58), (Z)-2-nonenal, β-damascenone, 1-octen-3-ol, Furaneol, and linalool were found to be the most odor-active. On the basis of their calculated odor activity values (OAV), isobutyl acetate, guaiacol, cis-rose oxide, 2-acetyl-2-thiazoline, β-damascenone, Furaneol, linalool, (E)-2-nonenal, geraniol, and isovaleric acid were determined to significantly contribute to the aroma of this fruit. GC/O analysis confirmed that 2-phenylethanol was probably responsible for the floral character and that the citrus-fruity aroma is due to the presence of many odor-active terpenes, particularly geraniol. Although cis-rose oxide was only 30% as active in GC/O as the most potent odor, its high OAV indicates its importance to the character of lychee odor. An unknown sesquiterpene-like compound (58), with a lychee-like odor characteristic of the fresh fruit, was identified by GC/O as being a highly odor potent compound. Taken together, the aroma of lychee was determined to be due to the interaction between compounds with floral, nutty, citrus, and fruity aromas.

Keywords: Aroma; GC/O; lychee; volatiles

Tomato fruits were eaten by one individual while expired air from the nose was sampled into an atmospheric pressure ionization-MS fitted with an air-sampling interface. The release of seven volatile compounds from four different types of tomato was followed, and the concentration of volatiles on the breath with time was determined. Different tomato types contained significantly different concentrations of each compound, resulting in a type-specific volatile “fingerprint”. However, the temporal aspects of the release profile of each compound were consistent across all types and were specific for that compound, except for enzymically released compounds from Delice tomatoes. Three classes of compound were identified in terms of their release characteristics. Some compounds (e.g., isobutylthiazole) are formed during ripening and show rapid release, other compounds are formed by the lipid oxidation pathway when tissue is macerated and are released rapidly (hexenal) or more slowly (hexenol) depending on the enzyme reactions that form them.

Keywords: Tomatoes; lipid oxidation; atmospheric pressure ionization; flavor; nosespace

Nineteen aromatic components were identified by GC/MS and quantified by GC-FID in 72 orange juices derived from the most widespread blond and blood cultivars grown in Itay. Naveline and Washington navel juices were characterized by a relatively high content of trans-2-hexenol; Valencia late was characterized by myrcene and Ovale calabrese by myrcene and linalool. Sanguinello and Moro juices were distinguished by valencene, whereas no single flavor differentiated Tarocco juices. Statistical treatment of the data by principal component and linear discriminant analyses pointed out the effectiveness of a reduced number of variables to discriminate most of the blond and blood juices, differentiating among their specific varieties. The most predictive flavors (myrcene and valencene among terpenes, hexenols and linalool among alcohols) are known to contribute powerful citrusy and fruity-green top notes, respectively.

Keywords: Flavor components; orange juices; multivariate analysis

The effect of pH, milk concentration, heating temperature, and heating time on the dissociation of casein from the micelles in reconstituted skim milk was investigated. For the 10% total solids milk samples, low levels of casein were rendered soluble at pH below 6.7 regardless of heating temperature, whereas increasing levels of casein were solubilized as the pH was increased from 6.7 to 7.1. The quantity of soluble casein increased with temperature to a maximum dissociation at about 60−80 °C, decreased as the temperature was raised to 100 °C, and then increased as the temperature was raised further. The dissociation behavior of α_s-casein and β-casein showed similar dependence on temperature to that of the total casein. In contrast, the dissociation of κ-casein increased with increasing temperature over the entire temperature range studied. Most casein dissociation occurred during the first minutes of heating, with little further change on prolonged heating. As the milk was concentrated, a higher level of dissociation of casein, particularly κ-casein, was observed at lower pH and at higher temperatures, particularly above 80 °C.

Keywords: Casein micelles; dissociation; heat treatment; reconstituted skim milk; concentrated skim milk

The disappearance of bitertanol, diazinon, iprodione, phosalone, and procymidone on field-sprayed apricots and their fate during sunlight- and oven-drying processes were studied. After treatments in the field, diazinon disappeared completely after a week, whereas the other pesticides at preharvest time showed residues 50% below MRLs. The pesticides decreased with pseudo-first-order kinetics and half-lives ranging from 9.1 to 24.4 days. The sunlight- and oven-drying processes caused the fruit to concentrate by a factor of ∼6 times. Nevertheless, the pesticide residues present in the dried fruit were lower than in the fresh fruit. The residue decreases were higher in the sunlight process than in the oven process. In the former, on average, the residues on the dried fruits were about half those on the fresh fruits, whereas in the latter they were about equal.

Keywords: Apricots; drying processes; pesticides; residues

The fate of the residues of benalaxyl, dimethoate, iprodione, metalaxyl, phosalone, procymidone, and vinclozolin in sunlight and oven raisin processing was studied. The drying process caused a fruit concentration factor of 4, while the decreases in residue with the two drying processes were different for the different pesticides. In sunlight-drying the residue level in the raisins was identical to that in the fresh fruits for benalaxyl, metalaxyl, and phosalone, whereas it was higher for iprodione (1.6) and lower for vinclozolin and dimethoate (one-third and one-fifth, respectively). The oven-drying process was preceded by washing, which caused residue decreases for iprodione and procymidone of 57 and 41%, respectively, whereas no decrease was observed in all of the other pesticides. During oven-drying pesticide residues in raisins with respect to fresh fruits showed an increase of 2.7 for phosalone, the same values for benalaxyl, metalaxyl, and procymidone, and lower values for vinclozolin and dimethoate. Sunlight-drying was more effective for phosalone and vinclozolin, whereas oven-drying was more effective for iprodione and procymidone, which was due to the washing effect rather than to dehydration. The experiments carried out with a model system showed that the decrease in dimethoate is attributable to heat, whereas in benalaxyl, procymidone, and phosalone it is due to codistillation and in iprodione and metalaxyl to the combined action of heat and codistillation.

Keywords: Raisin; drying processes; pesticides; residues

Carrot pulp waste was used as raw material for processing carotenoid powder by spray-drying, and the stability of carotenoid in the powder was studied under light and dark storage at various temperatures. The various carotenoids were analyzed by HPLC with photodiode array detection. Results showed that the most appropriate condition for processing carotenoid powder by spray-drying consists of 15% solid content of feed, with inlet air temperature of 135−145 °C and outlet air temperature of 90−100 °C. The total amount of all-trans plus cis forms of lutein, α-carotene, or β-carotene in the carotenoid powder decreased with increasing storage time and temperature, and the degradation rate of each fits the first-order model. The major cis isomers formed in the dark were 13-cis-α-carotene and 13-cis-β-carotene, whereas 9-cis isomers of both α- and β-carotene predominated under light. A high correlation was also observed between color changes and carotenoid content.

Keywords: Carotenoid powder; carrot pulp waste; spray-drying; carotenoid stability

A 2³ factorial experimental design was used to investigate the effect of washing in combination with precooking on the oxidative stability of lipids in minced herring (Clupea harengus) at −18 °C. The following variables were studied:  washing (no, yes), cooking time (38, 54 min), and cooking temperature (55, 100 °C).The responses monitored were peroxide value (PV), absorbance at 234 nm (A₂₃₄), absorbance at 268 nm (A₂₆₈), and lipid soluble fluorescent products (FP). A partial least-squares regression analysis (PLS) revealed that the best lipid stability was obtained at minimum cooking time and at lower temperature. On the basis of compositional analyses and in vitro experiments, this finding was proposed to be due to heat inactivation of catalytic enzymes, without simultaneous activation, for example, of hemoproteins. Washing reduced these benefits from precooking by removal of pro-oxidative enzymes and also through a reduction in the amount of antioxidants as well as a relative increase in phospholipids and free fatty acids in the fat.

Keywords: Clupea harengus; herring; lipid oxidation; washing; precooking

The amino acid composition of two sets of commercial orange juice was determined, and the mean value and range of values for each amino acid were tabulated. Single-strength juices from concentrates showed lower content of amino acids than straight-processed juices. Statistical comparison by ANOVA revealed statistical significance (p ≤ 0.001) for aspartic, arginine, asparagine, glutamine, serine, threonine, and isoleucine, between straight-processed orange juices, and those single-strength juices from concentrates. The combination of glutamine, asparagine, and alanine allowed a 100% correct classification.

Keywords: Commercial orange juices; amino acids; discriminant analysis

Tannic composition was studied in reproduction cork samples from three different trees of Spanish Quercus suber and at different industrial processing stages. The ellagitannins, roburins A and E, grandinin, vescalagin, and castalagin, were identified and quantified by HPLC. Global evaluations of tannins were also carried out, using classical chemical methods. The group of hydrolyzable tannins was the most abundant in the tannic extract in all samples; among them, castalagin was the main component, followed by vescalagin, grandinin, roburin E, and, to a much lesser extent, roburin A. The changes in tannic composition throughout the industrial processing are mainly related to the boiling process and are more pronounced in total phenol and proanthocyanidin contents than in individual ellagitannins content. Vescalagin and roburins A and E were selected as those variables that provided the greatest discrimination among stages. Important differences in the ellagitannin contents were observed among the trees studied, all of the ellagitannins being discriminant variables in this case.

Keywords: Quercus suber; cork; tannins; ellagitannins; proanthocyanidins; polyphenols; high-performance liquid chromatography

Naphthalene was detected in nest cartons of Formosan subterranean termites, Coptotermes formosanus Shiraki. The concentration of naphthalene ranges from 50.56 to 214.6 μg/kg. This is the first report of naphthalene being associated with termites. Some possible functions of naphthalene in a termite society are discussed.

Keywords: Naphthalene; Coptotermes formosanus; termite nest

Sixteen male strawberry harvesters were monitored during two 3-h harvesting periods for dermal exposure to abamectin, a miticide/insecticide. Upper body exposures were monitored by cotton undershirt dosimetry, hand rinses, and facial washes. Exposure was greatest to the hands (833 ng/h) followed by the torso (380 ng/h) with negligible residues detected on the face. With <1% dermal penetration, the average systemic exposure was calculated to be 1.36 ng/kg/day. The ratio of the no-observed-effect level (NOEL) of 50 μg/kg/day to the worker exposure of 1.36 ng/kg/day yielded a margin of exposure (MOE) of 36 800. Abamectin foliar residues ranged from 40.7 to 0.17 ng/cm² at 2 h and 7 days after the second application, respectively. Dislodgeable foliar residue (DFR) data at the harvest time of 3 days after the second application, 0.84 ng/cm², combined with the Zweig transfer factor (5000 cm²/h) and a dermal penetration of 1% resulted in a predicted worker exposure of only 5.6 ng/kg/day and a corresponding MOE of 8930. These results suggest that DFR data may be used to conservatively predict worker exposure to abamectin.

Keywords: Abamectin; dislodgeable foliar residues (DFR); worker exposure

The effect of Triton X-100 (TX-100) on the penetration of benzyladenine (BA) through isolated tomato (Lycopersicon esculentum Mill.) fruit cuticular membranes was studied using finite and infinite dose diffusion and sorption/desorption systems. Finite dose penetration of BA (18 and 160 μM, pH 2 and 6) from donor droplets (3 μL) was characterized by an initial time lag, a maximum rate of penetration, and total penetration. TX-100 (0.1% w/v) increased maximum BA penetration rates 1.5−40-fold (pH 6, 18 and 160 μM) and total penetration 1.5−3-fold (pH 2 and 6, 18 and 160 μM BA). In infinite dose studies, rates of BA penetration (20 μM, pH 6.0) were increased ∼2-fold by TX-100. Surfactant effects were greatest when the surfactant was presented to the outer morphological surface of the cuticle (both native and dewaxed) regardless of whether TX-100 was penetrating in the same or opposite direction to BA. Sorption/desorption of BA was not affected by TX-100.

Keywords: Cuticle; cytokinin; diffusion; Triton X-100; sorption; Lycopersicon esculentum

The development of an integrated system for an on-line supercritical fluid extraction/cleanup/supercritical fluid chromatography/mass spectrometry analysis (SFE/SFC/MS) of thermally labile carbamate pesticides from beef and chicken meat samples is discussed. A key to the system is the mixed stationary phase (7% diol in C₁₈) used in the cleanup column to separate target analytes from the extracted lipid matrix interferences. The detection limits of the system at 2:1 signal to noise ratio were 200 and 175 ppb for bendiocarb and carbaryl, respectively. The reproducibility of the present system was not totally favorable due to trapping problems, resulting from frequent clogging of either the cryogenic retention gap between the extraction cell and the SFC or the actual restrictor in the retention gap. Operating in an integrated mode, 53% of the experiments were completed without complications connected to extracting and detecting the analyte.

Keywords: Carbamates; pesticides; SFE; SFC; integrated system; on-line cleanup; animal tissues

The degradation and mobility of sulfometuron-methyl and potential degradates were evaluated under actual field conditions in the United States following application of Oust herbicide to bare ground at the maximum labeled rate. Sulfometuron-methyl degraded rapidly at the four test sites; calculated half-life (t_1/2) values ranged from 12 to 25 days. Sulfometuron-methyl residues were below the limit of quantitation (10 ppb) beyond 90 days after treatment (DAT) at all test sites. The highest degradate concentration present at the end of the study (359 DAT) was 40 ppb (the herbicidally inactive 2-amino-4,6-dimethylpyrimidine). Sulfometuron-methyl and its degradates were immobile under field conditions.

Keywords: Sulfometuron-methyl; degradation; mobility; half-life; soil

Butter fat/canola oil blends ranging from 100% butter fat (w/w) to 60:40% butter fat/canola oil were enzymatically interesterified with an sn-1,3 specific lipase from Rhizopus arrhizus in a liquid/solid two-phase system. Interesterification progress was monitored by following the changes in the relative proportions of 50-carbon triacylglycerols (TAGs) to 38-carbon TAGs (50/38 ratio) as a function of reaction duration. Most of the changes in TAGs occurred within the first 24 h of reaction. As the proportion of oil in the blend increased, greater changes in TAG composition became apparent. The interesterification reaction was optimal at 0.35% water content (w/w). The initial rate of hydrolysis was linearly dependent on initial water content within the range 0−0.55% water (w/w). Free fatty acids released ranged from 3 to 4.5% after 96 h of interesterification. The predominant free fatty acids were oleic acid (18:1) and palmitic acid (16:0). The lipase displayed little activity toward butyric acid (4:0) and caproic acid (6:0) residues. Monoacylglycerol levels ranged from 1.4 to 2.4% and diacylglycerol levels from 1.5 to 2.0% in all blends.

Keywords: Rhizopus arrhizus; butter fat; canola; interesterification; lipase-catalyzed; oil

The effects of sn-1,3 specific Rhizopus arrhizus lipase-catalyzed enzymatic interesterification on the physical properties of butter fat/canola oil blends [100% butter fat (w/w) to 60% butter fat/40% canola oil (w/w) (60:40)] were determined. Enzymatic interesterification (EIE) lowered and linearized the solid fat content (SFC) versus temperature profile of all noninteresterified (NIE) blends in the 5−40 °C range. The largest drops in SFC as a result of EIE occurred with native butter fat between 5 and 10 °C. Dropping points (DP) decreased 1−3 °C for all blends upon interesterification, and the decrease in DP as a function of canola oil proportion in the blend was more pronounced for the EIE than for the NIE blends (0.16 °C/wt % versus 0.10 °C/wt %, respectively). Isothermal crystallization behavior monitored turbidimetrically (onset of crystallization) showed that EIE did not alter the crystallization behavior of butter fat, yet did alter that of the blends. Rheological characterization included large and small deformation tests. Cone penetrometry, used to gauge the former, indicated that both blending and EIE diminished the hardness index (HI) in a nonlinear fashion. Reductions in HI resulting from EIE predominantly occurred within 12 h of interesterification. Oscillatory frequency sweep measurements at small amplitude showed that EIE blends had lower storage (G‘) and loss moduli (G‘‘) than their NIE counterparts. Blending of butter fat with canola oil and subsequent interesterification modified the crystal morphology and X-ray diffraction patterns of butter fat. Polarized light microscopy revealed that addition of canola oil led to slight aggregation of the crystal structure, whereas EIE led to more pronounced aggregation of the crystalline mass. X-ray diffraction analysis revealed a predominance of β‘ and a small proportion of β crystals for all samples examined with greater presence of β crystals in the EIE blends vis-à-vis the NIE blends. Long spacings increased from ∼41.5 to 44 Å following EIE. The fractal dimension of the butter fat/canola oil blends diminished from 2.59 to 2.50 following interesterification. These results suggest that changes in the rheological properties of butter fat induced by enzymatic interesterification were closely linked to changes in the SFC and, to a lesser extent, to the distribution of crystal mass within the fat crystal network.

Keywords: Rhizopus arrhizus; butter fat; canola; interesterification; lipase-catalyzed; oil

A crude lipoxygenase (FI) extract from Fusarium proliferatum was partially purified by ammonium sulfate precipitation (FII). The purification of fraction FII by size-exclusion chromatography resulted in three major peaks, FIIIa, FIIIb, and FIIIc. Fraction FIIIa demonstrated the highest specific lipoxygenase activity as well as the highest recovery and was therefore further purified. The purification procedure resulted in one major fraction (FIV) by ion-exchange chromatography, and the presence of one major and two minor protein bands in both the native and sodium dodecyl sulfate−polyacrylamide gel electrophoresis patterns. The purified enzyme demonstrated approximately 2.5 times more activity toward mono- and dilinolein and 1.5 times more with linolenic and arachidonic acids than that exhibited toward linoleic acid at pH 6.0; however, at pH 10.5, this enzymatic fraction possessed an overall preference toward linoleic acid. The purified fraction produced mainly the 13-hydroperoxides (HPODs) from linoleic acid at pH 6.0 and the 9- and 13-HPODs, at a ratio of approximately 1:1, at pH 10.5. In addition, the presence of a lipoxygenase activity producing the 10- and 12-HPODs was also suggested at pH 10.5.

Keywords: Lipoxygenase; Fusarium proliferatum; purification; characterization

Changes in aroma compounds of pale dry sherry wines (“Fino”) subjected to biological aging by means of two strains of the “flor” film yeasts Saccharomyces cerevisiae races capensis and bayanus were studied. The results were subjected to a multifactor analysis of variance. For the compounds showing a dependence at the p < 0.01 level simultaneously with the yeast strain and aging time, a principal component analysis was performed, accounting for 92.89% of the overall variance for the first component. This component was mainly defined by acetaldehyde, 1,1-diethoxyethane, and acetoin, which in high concentrations are typical of aged sherry wines, contributing strongly to their sensory properties. The strain of S. cerevisiae race bayanus was more suitable for the biological aging, mainly as a result of the faster production of the three compounds mentioned above. Therefore, the bayanus strain could be used for endowing more rapidly aged sherry wines.

Keywords: Biological aging; wine aromas; film yeasts; sherry wine

Improved nutrient-use efficiency in cropping systems is needed to increase farm income and to minimize possible nutrient emission to the environment. Plant glutamate dehydrogenase (GDH) offers a means for improved diagnosis of the nutrient status of crops. Zea mays L. DK-68 was fertilized with nutrient solutions containing different ratios of nitrogen, phosphorus, and potassium (N, P, K). Maize shoot GDH was fractionated to its population of isoenzyme by Rotoforation followed with native PAGE. The GDH of the control maize had the complete set of 28 isoenzymes. Fertilization of the maize with N₁P₁K₁ did not repress the 14 anodal but did repress the 14 cathodal isoenzymes. As the P content of the fertilizer increased in the sequence N₀P₀K₀, N₁P₀K₁, N₀P₁K₀, N₁P₁K₁, N₀P₂K₀, and N₀P₄K₀, the amination maximum velocity (V_max) of the enzyme decreased curvilinearly in the sequence 310, 246, 140, 130, 108, and 83 μmol min^-1 mg^-1, respectively. The highest dry matter yield occurred when the fertilizer contained 1−3 mM P_i, which was thus the nutrient deficiency−sufficiency interphase. In the GDH integration of the signals from the N, P, and K so as to respond with a characteristic isoenzyme population pattern, the signal from N superseded that from K; in turn, the signal from P superseded those from N and K. Signal integration was therefore based on the dominance by the most nucleophilic nutrient. In this case, the decreasing order of nucleophilic dominance was PO₄^3- > NH₄⁺ > K⁺.

Keywords: Zea mays; glutamate dehydrogenase; NPK signal integration

Melon (Cucumis melo L.) is an excellent system to study the role of proline in regulating benzyladenine-induced shoot organogenesis, which is also an important system in our laboratory for investigating flavor and antioxidant metabolite synthesis in differentiated tissues. We have hypothesized that proline stimulated in vitro shoot organogenesis through the activation of the proposed proline-linked pentose phosphate pathway, which may regulate endogenous cytokinin and auxin biosynthesis. To further investigate this hypothesis, it is essential to first confirm whether benzyladenine-induced shoot organogenesis can be stimulated by enhancing proline synthesis through the use of proline analogues and ornithine (proline precursor). In this study, benzyladenine-induced shoot organogenesis was substantially stimulated by exogenous proline and/or ornithine in combination with proline analogues such as azetidine-2-carboxylate (A2C) and hydroxyproline (HP). Among these treatments, proline in combination with A2C or HP showed the highest stimulation. The stimulation of organogenesis correlated closely with increased levels of endogenous proline content, thereby strengthening the hypothesis that proline-linked activation of purine and aromatic metabolism via the stimulation of pentose phosphate pathway may be important for in vitro organogenesis in melon.

Keywords: Azetidine-2-carboxylate; benzyladenine; Cucumis melo; hydroxyproline; ornithine; pentose phosphate pathway; proline; purine synthesis; shoot organogenesis; thioproline

This paper reports the synthesis of haptens and the generation and preliminary evaluation of polyclonal antibodies for the detection of dioxins such as TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) by ELISA (enzyme-linked immunosorbent assay). These novel haptens contain unsaturation between the halogenated dibenzo-p-dioxin ring system and the protein to which it is conjugated, presenting a rigid handle structure. The substitution pattern is identical with or similar to that of TCDD (i.e., 2,3,7,8- or 1,2,3,7,8-). Finally, the haptens lack polar groups for hydrogen bonding. In direct binding assays using the new polyclonal antibodies there was excellent recognition of hapten−protein conjugates, including recognition of those hapten conjugates that were not used as immunogens (i.e., assay systems heterologous in hapten structure). These haptens do elicit selective immune responses in rabbits. Their evaluation in an ELISA format demonstrated the usefulness of these haptens for the detection of dioxins. An IC₅₀ of 0.8 ng/well (16 ng/mL) was observed for an unoptimized system that used 2,3,7-trichloro-8-methyldibenzo-p-dioxin as an analytical surrogate standard.

Keywords: TCDD; dioxin; immunoassay; polyclonal antibodies; hapten synthesis; polychlorinated hydrocarbons

With the aim of developing an immunoassay for the detection of the insecticide methiocarb, three compounds with carboxylic spacer arms of different lengths introduced at the carbamate group were synthesized, conjugated to proteins, and used as immunizing haptens in mice. Monoclonal antibodies (MAbs) were subsequently obtained and characterized for their affinity to methiocarb. In the homologous conjugate-coated assay format, MAbs exhibited I₅₀ values in the 1−10 nM range. Thereafter, a collection of methiocarb haptens with modifications in the aromatic ring structure or in the spacer arm were synthesized to be used as heterologous haptens. These haptens and MAbs were incorporated into several ELISA configurations. Some of the new combinations of immunoreagents and assay format provided a significant improvement in assay sensitivity, reaching I₅₀ values around 0.1 nM. MAbs seem to be very specific for methiocarb, as evidenced by the negligible cross-reactivity shown by methiocarb metabolites. These immunoreagents are very promising analytical tools for the rapid and sensitive determination of methiocarb in food and in the environment.

Keywords: ELISA; immunoassay; insecticide; monoclonal antibodies; hapten design; hapten heterology; ELISA format; carbamate

Commercial protease preparations have been screened for their biocatalytic activity in the esterification of various fatty acids with 1-butanol. Of all protease preparations tested, only those from pineapple (bromelain) and Rhizopus sp. were found to contain active lipases. Similar to lipases from microorganisms, animals, and plants, such as papaya (Carica papaya) latex, lipases in the protease preparations of bromelain and Rhizopus sp. strongly discriminated against fatty acids having a cis-4 unsaturation, for example, all-cis-4,7,10,13,16,19-docosahexaenoic acid, cis-6 unsaturation, for example, petroselinic (cis-6-octadecenoic), γ-linolenic (all-cis-6,9,12-octadecatrienoic), and stearidonic (all-cis-6,9,12,15-octadecatetraenoic) acid, as well as cis-8 unsaturation, for example, dihomo-γ-linolenic (all-cis-8,11,14-eicosatrienoic) acid. Fatty acids having a cis-9 unsaturation, for example, oleic (cis-9-octadecenoic) and α-linolenic (all-cis-9,12,15-octadecatrienoic) acids, were very well accepted as substrates by both protease preparations. Fatty acids having hydroxy groups, for example, ricinoleic (12-hydroxy-cis-9-octadecenoic) and 12-hydroxystearic acid, epoxy groups, for example, trans-9,10-epoxystearic acid, and cyclopentenyl groups, for example, hydnocarpic [(11-(2‘-cyclopentenyl)undecanoic] and chaulmoogric [13-(2‘-cyclopentenyl)tridecanoic] acid, were also well accepted as substrates by both enzyme preparations.

Keywords: Protease; lipase, biocatalyst; enzymatic esterification; fatty acid specificity

Complementary DNA encoding hen egg white lysozyme (HEWL) was subjected to site-directed mutagenesis to introduce two N-linked glycosylation sites (Asn¹⁹-Try²⁰-Thr²¹ and Asn⁴⁹-Ser⁵⁰-Thr⁵¹) into both positions 19 and 49 by substituting Arg-21 with Thr and Gly-49 with Asn, respectively. The double-glycosylated lysozyme R21T/G49N was expressed in Saccharomyces cerevisiae carrying the yeast expression plasmid inserted the double-mutant HEWL cDNA. The mutant lysozyme mainly secreted a polymannosyl form with a small amount of two oligomannosyl forms. The polymannosyl lysozyme R21T/G49N was glycosylated at two positions, 19 and 49, with a polymannosyl and an oligomannosyl chain. The lengths of the polymannosyl and oligomannosyl chains attached to R21T/G49N were approximately 272 and 18 mannose residues, respectively. The R21T/G49N showed better emulsifying properties than two types of single-polymannosyl lysozymes R21T and G49N. With regard to single-polymannosyl lysozyme, G49N showed somewhat better emulsifying properties than R21T. In addition, the cleavage of polymannosyl chain from lysoyme with endo-β-N-acetylglucosaminidase resulted in a dramatic decrease in the emulsifying properties of polymannosyl lysozymes.

Keywords: Lysozyme; yeast expression system; genetic modification; polymannosylation; double glycosylation; emulsifying properties