Effect of (-)-epigallocatechin gallate palmitate complexation under mild temperature on the structure and nutritional functions of porous rice starch.

The correlation among the hierarchical structure, physicochemical properties, and nutritional functions of porous rice starch after absorbing and complexing with (-)-epigallocatechin gallate palmitate (P-EGCG) under mild temperatures at different reaction times were investigated. The P-EGCG loading rate (19.6 %-28.5 %) of porous starch increased after hydrolysis with a mixture of amyloglucosidase and α-amylase for 3 and 6 h, respectively. A decrease in the melting enthalpy of the amylopectin double helix and an increase in the melting enthalpy of the V-type helices after complexation was observed with longer reaction times. The retention index of P-EGCG after 6 h of incubation was 57.11 % following 21 d of storage. These structural changes significantly transformed portions of the rapidly and slowly digestible starches into resistant starch (41.68 %-47.84 %), accompanied by enhanced thermal stability, antioxidant activity, and enteropathogenic bacteria-inhibiting ability. Therefore, porous rice starch complexed with P-EGCG may provide controlled digestion, antioxidant activity, and potential gut microbiota benefits.