Kinetic fingerprinting and food matrix interactions reveal the gastrointestinal behavior of polyphenolics in stir-fried green tea.

Abstract

Stir-fried green tea polyphenols exhibit strong antioxidant capacity; however, they degrade rapidly during gastrointestinal transit. This study combined antioxidant kinetic profiling, chemometric analysis, simulated digestion, and Caco-2 cell permeability models to identify the principal antioxidant drivers and evaluate the protective effects of the food matrix. Ridge model identified EGCG as the primary determinant of radical-scavenging kinetics, whereas gallic acid contributed more strongly to the thermodynamic antioxidant capacity. Simulated intestinal digestion induced an antioxidant kinetic collapse, driven by rapid deprotonation and auto-oxidation of pyrogallol-type catechins at mildly alkaline pH, thereby reducing EGCG bioaccessibility by 79.3% and reaction velocity by 60% in the aqueous extract. However, co-digestion with a yogurt matrix rescued these phytochemicals, significantly increasing EGCG bioaccessibility from 13.1% to 46.2% and intestinal permeability from 2×10-6 to 4.18×10-6cm/s. Molecular docking suggests that β-casein binds EGCG through hydrophobic and hydrogen bonding interactions. An exploratory tool, known as the Biological Relevance Factor (BRF), integrates potency, bioaccessibility, and permeability, confirming that while specific phytochemicals dictate initial antioxidant response, food matrix interactions ensure sustained antioxidant effects.