Interaction between amylose/amylopectin and polyphenols of different structures

This study aims to systematically elucidate the interaction mechanism between four polyphenols and amylose/amylopectin through integrated experimental and computational approaches. Catechin (CC) and epigallocatechin gallate (EGCG) exhibit excellent binding capacities for amylose/amylopectin, followed by cyanidin-3-O-glucoside (C3G), while ferulic acid (FA) exhibits the lowest binding capacity. Polyphenols induce starch chain aggregation, increasing particle sizes (amylose: 152.1 → 157.78 nm; amylopectin: 96.2 → 95.4 nm) and reducing the short-range ordered structure (full width at half-maximum of the 480 cm^-1 band in LCM-Raman spectra increases; FTIR absorbance ratios R_1050/1022 and R_995/1022 decrease by 13.43 % and 7.35 %, respectively). Molecular dynamics (MD) simulations reveal that polyphenols disrupt helical structures and act as the "bridges" crosslink adjacent starch chains. Hydroxyl groups of polyphenols and the C6 position of starch glucose residues drive binding by hydrogen bond; the binding capacity increases with hydroxyl group number (FA < CC < EGCG). In contrast, C3G, as a flavylium cation, primarily interacts via electrostatic forces. This study innovatively combines experimental characterization and MD approaches to provide atomistic insights into starch-polyphenol interactions, aiding the design of starch-based delivery systems.