The influence of the polyphenolic compound epicatechin on Maillard chemistry was investigated under simulated roast conditions (10% moisture at 220 degrees C for 10 min). Quantitative gas chromatography (GC) analysis indicated that the addition of epicatechin to glucose or fructose/glycine model systems significantly reduced the generation of hydroxyacetone, 2-methylpyrazine, 2,3,5-trimethylpyrazine, furfural, 2-acetylfuran, 5-methylfurfural, 2(5H)-furanone, 2-acetylpyrrole, and furfuryl alcohol. These analytes were reported to be primarily generated from intact C2, C3, C4, C5, and C6 sugar fragments based on gas chromatography/mass spectrometry quantitative isotopomeric analysis of a 1:1 13C6:12C6 hexose sugar/glycine model system. Liquid chromatography/mass spectrometry qualitative isotopomeric analysis of a 1:1 13C6:12C6 hexose sugar/glycine/epicatechin model systems confirmed epicatechin reacted with Maillard reactants in the model systems; two main reaction products were reported, epicatechin-C5 and -C6 sugar fragment adducts. In addition, LC/MS analysis of a model system consisting of only 3-deoxy-2-hexosulose and epicatechin identified 3-deoxy-2-hexosulose as a precursor of the epicatechin-C5 and -C6 sugar fragment adducts reaction products. These results imply that epicatechin quenched 3-deoxy-2-hexosulose (a key source C6 to C1 sugar fragments) and consequently inhibited Maillard product formation.