Epicatechin and epigallocatechin gallate inhibit formation of intermediary radicals during heating of lysine and glucose

• Published in: Food chemistry Vol. 146; pp. 48 - 55
• Main Authors: Yin, J., Hedegaard, R.V., Skibsted, L.H., Andersen, M.L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2014; Elsevier
• Subjects: Biological and medical sciences; Camellia sinensis - chemistry; Catechin - analogs & derivatives; Catechin - chemistry; EGCG; ESR; Food toxicology; Free Radicals - chemistry; Glucose - chemistry; Hot Temperature; Hydrogen-Ion Concentration; LC–MS; Lysine - chemistry; Maillard Reaction; Maillard reactions; Medical sciences; Oxygen consumption; Plant Extracts - chemistry; Toxicology; Maillard reactions; Oxygen consumption; ESR; EGCG; EC; LC–MS; Gallic acid; Epigallocatechin-3-gallate; Maillard reaction; Glucose; Antioxidant; Flavonoid; Epicatechin; Micronutrient; Polyphenol; LC-MS; Heating; Lysine; Aminoacid; Phenols; Carbohydrate; Proanthocyanidin
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.09.032

•Green tea catechins inhibit radical formation during Maillard reaction.•Autoxidation products of catechins react with lysine.•EGCG inhibits radical formation more efficiently than epicatechin. High concentrations of the tea catechins epicatechin (EC) or epigallocatechin gallate (EGCG) inhibited formation of highly reactive intermediary radicals appearing during the Maillard reactions (MR), that take place during heating glucose and lysine at 70°C in EtOH/HEPES buffer at pH 7.0 and pH 8.0. Radicals were trapped by ethanol, which subsequently were converted into spin adducts of the spin trap α-(4-pyridyl N-oxide)-N-tert-butylnitrone (POBN). EGCG was found to be more efficient than EC as inhibitor of intermediary radicals during the MR. Based on UV/Vis-spectroscopy, measurement of oxygen consumption and LC–MS detection of intermediates, it is suggested that the quinone form of autoxidised EC reacts with lysine through either a Michael type addition or a “Strecker like” reaction and thereby influences the formation of intermediary MR products as well as radicals.