Interactions between protein, lipid and starch in foxtail millet flour affect the <i>in vitro</i> digestion of starch

Abstract

This study aimed to explore the mechanism whereby the interactions between the endogenous proteins, lipids and starches present in foxtail millet affected the in vitro hydrolysis of starch. Prior proteolysis of the protein matrix significantly increased the enzymatic hydrolysis of foxtail millet starch, suggesting that it is possible that non-surface proteins (i.e. the protein matrix) can retard the rate of starch degradation by acting as a physical barrier between starch and amylase. Furthermore, confocal microscopy demonstrated that the proteins in foxtail millet bind competitively with starch to α-amylase, partially decreasing the activity of α-amylase. In addition, as a result of complexing with the fatty acids, foxtail millet starch had a significantly reduced hydrolysis rate. Therefore, we conclude that the interactions between endogenous proteins and lipids with starch plays a significant role in the hypoglycemic properties of foxtail millet.