title: Antioxidant and pro-oxidant activity of (-)-epigallocatechin-3-gallate in food emulsions: Influence of pH and phenolic concentration.
abstract: Polyphenols have been observed to exert both antioxidant and pro-oxidant activity in lipid foods, and factors that influence that net effect include both polyphenol concentration and matrix pH. In this study, the effects of concentration (1-500 μM) of a model polyphenol, (-)-epigallocatechin-3-gallate (EGCG), and matrix pH (2-7) on the net anti-/pro-oxidant activity of EGCG in flaxseed oil-in-water (o/w) emulsions were systematically evaluated. After 24h, EGCG (5-100 μM) was observed to exhibit pro-oxidant activity in low pH (pH 2-4) emulsions, as determined by conjugated dienes (CDs) and thiobarbituric acid reactive substances (TBARSs) production. At the higher pH values studied (pH 5-7), lower CD and TBARS concentrations were detected in samples with 25-500 μM EGCG at 24h. Overall, EGCG concentration and pH both played significant roles in determining net antioxidant or pro-oxidant effects, with the largest antioxidant and pro-oxidant effects observed at the higher EGCG concentrations (100-500 μM) tested.
authors: Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
authors: Lisa
authors: L
authors: Zhou
authors: Ryan J
authors: RJ
authors: Elias
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008043:Linseed Oil / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D017392:Thiobarbituric Acid Reactive Substances / Q000737:chemistry
chemical_list: D000975:Antioxidants; D004655:Emulsions; D016877:Oxidants; D010636:Phenols; D017392:Thiobarbituric Acid Reactive Substances; D008043:Linseed Oil; D002392:Catechin; C045651:epigallocatechin gallate