Structure and in Vitro Digestibility of Normal Corn Starch: Effect of Acid Treatment, Autoclaving, and β-Amylolysis

The goal of this study was to explore a new strategy to reduce the digestibility of normal corn starch (NCS). NCS was treated using 1.0% hydrogen chloride at 55 degrees C. After neutralization and desalting, starches were adjusted to 35% moisture content and subjected to autoclaving. Thereafter, starches were subjected to beta-amylolysis. At different stages, starches were characterized for chain length distribution, ordered structure including the crystalline pattern, and in vitro digestibility. The results showed that acid treatment reduced amylose molecular weight and increased the thermal resistance of A-type crystallites. V-type crystallites promoted by autoclaving were increased by acid treatment, suggesting the beneficial effect of reduced amylose molecular weight on crystallization. beta-Amylolysis had minor impact on the crystalline pattern; however, it significantly reduced the in vitro digestibility of starch by enriching linear chains. At higher levels of acid treatment, the effect of beta-amylolysis was more pronounced.