Molecular structure and enzymatic hydrolysis properties of starches from high-amylose maize inbred lines and their hybrids

Abstract

High-amylose maize starch has health benefits and special industrial uses. In this study, starches were isolated from normal maize and high-amylose inbred and hybrid maizes. Their molecular structure and enzymatic hydrolysis properties were investigated and analyzed. The high-amylose hybrid maize starch contained lower amylose, intermediate component, amylopectin long branch-chains, and amylopectin average chain length, and higher amylopectin short branch-chains than did high-amylose inbred maize starch. High-amylose maize starch was more resistant to α-amylase and amyloglucocidase hydrolysis and had a significantly lower hydrolysis rate coefficient than normal maize starch did. The native, gelatinized and retrograded starches of the high-amylose hybrid maize had significantly higher rapidly digestible starch and lower resistant starch than those of the high-amylose inbred maize. The retrogradation of gelatinized starch markedly increased the resistance of high-amylose starch to in vitro digestion. The high contents of amylose and intermediate component and the long branch-chains of amylopectin increased the resistance of maize starch to enzymatic hydrolysis and in vitro digestion.