Web Release Date: June 2,
Sensory-Guided Decomposition of Roasted Cocoa Nibs (Theobroma cacao) and Structure Determination of Taste-Active Polyphenols
and
Deutsche Forschungsanstalt für Lebensmittelchemie, Lichtenbergstrasse 4, D-85748 Garching, Germany, and Institut für Lebensmittelchemie, Universität Münster, Corrensstrasse 45, D-48149 Münster, Germany
Received for review March 1, 2005. Revised manuscript received April 28, 2005. Accepted April 28, 2005. This research project was supported by a grant from FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn, Germany), the AiF (Arbeitsgemeinschaft industrieller Forschung), and the German Ministry of Economics (Project 13235 N).
Abstract:
Sequential application of solvent extraction, gel permeation chromatography, and RP-HPLC in
combination with taste dilution analyses, followed by LC-MS and 1D/2D-NMR experiments and thiolytic
degradation, revealed that, besides theobromine and caffeine, the flavan-3-ols epicatechin, catechin,
procyanidin B-2, procyanidin B-5, procyanidin C-1, [epicatechin-(4
8)]3-epicatechin, and [epicatechin-(48)]4-epicatechin were among the key compounds contributing to the bitter taste as well as the
astringent mouthfeel imparted upon consumption of roasted cocoa. In addition, a series of quercetin,
naringenin, luteolin, and apigenin glycopyranosides as well as a family of not previously identified
amino acid amides, namely, (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid, (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine, (+)-N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-aspartic acid, and (+)-N-(E)-cinnamoyl-L-aspartic acid, have been
identified as key astringent compounds of roasted cocoa. Furthermore, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine (clovamide), (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-tyrosine (deoxyclovamide), and (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, reported previously as antioxidants,
have been found as contributors of cocoa's astringent taste. By means of the half-tongue test, the
taste thresholds of flavan-3-ols and glycosides have been determined.
Keywords: Cocoa beans; astringency; bitter taste; taste dilution analysis; half-tongue test; (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid; (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid
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