Epicatechin-Promoted Formation of Acrylamide from 3-Aminopropionamide Via Postoxidative Reaction of B-Ring

The role of thermally generated 3-aminopropionamide as an intermediate in acrylamide formation in the Maillard reaction has been well established. Herein, the effect of epicatechin on the conversion of 3-aminopropionamide into acrylamide under oxidative conditions was investigated at 160-220 °C. Epicatechin promoted acrylamide generation and 3-aminopropionamide degradation. The stable isotope-labeling technique combined with UHPLC-Orbitrap-MS/MS analysis showed adduct formation between 3-aminopropionamide and the oxidized B ring of epicatechin to form a Schiff base. This initially formed Schiff base could directly degrade to acrylamide, undergo reduction or dehydration to other intermediates, and subsequently generate acrylamide. Based on accurate mass analysis, five intermediates with intact or dehydrated C rings were tentatively identified. Furthermore, reaction pathways were proposed that were supported by the changes in the levels of adducts formed during heating. To the authors' knowledge, this study is the first to reveal pathways through which flavanols promoted the formation of acrylamide in Maillard reactions.