Effects of Endogenous Polyphenols in Acorn (Quercus wutaishanica Blume) Kernels on the Physicochemical Properties of Starch

Abstract

AbstractThe effects of endogenous polyphenols in acorn kernels on granule morphology, crystal properties, and in vitro digestibility of starch are investigated. The granule surface smoothness, relative crystallinity, short‐range molecular order, and starch hydrolysis rate increase after the removal of polyphenols from acorn flour. With the addition of polyphenol extracts, the hydrolysis rates of acorn, corn, potato, and chestnut starches are all reduced, and the free‐polyphenol extract shows higher inhibitory activity than the bound‐polyphenol extract. These results are expected to be helpful for understanding the low digestibility of starch in acorn kernels, which is attributed to the inhibitory effects of polyphenols on the activities of α‐amylase and α‐glucosidase, but not the increase of long and short‐range molecular orders of starch.