Effects of anthocyanins on bread microstructure, and their combined impact on starch digestibility

Abstract

Several studies have confirmed the reduction of starch digestibility with anthocyanins in food systems via mechanisms of enzyme inhibition. However, starch-polyphenol interactions may also contribute to this reduction, by modifying food microstructures and physicochemical properties of starch. The interactions among anthocyanins, starch digestibility, and food microstructures are significant to clarify the digestion processes of fortified food systems, but its interrelationship lacks clarity. Hence, we aim to evaluate the effects of black rice anthocyanin extract (BRAE) incorporation on the microstructural changes of wheat bread, in relation to overall digestibility. Overall, BRAE incorporation demonstrated a dose-dependent reduction in starch digestibility. Physicochemical analyses reflected that BRAE incorporation decreased starch gelatinisation and increased crystallinity. Microscopic imaging revealed differentiating microstructural characteristics of starch and gluten with BRAE incorporation, supporting the reduction in digestibility. Our results conclusively demonstrate that BRAE incorporation in bread suppresses starch digestibility not only through enzyme inhibition, but also food microstructural modifications.

Keywords: Anthocyanins; Digestibility; Functional food; Microstructure; Starch.