Differential scanning calorimetry and a model calculation of starches annealed at 20 and 50 °C

Corn, wheat, and potato starches were annealed at 20 and 50 °C, and the gelatinization phenomena were observed with differential scanning calorimetry (DSC). Amylose content and amylopectin chain length distribution were not changed by the annealing treatment. The DSC endotherm associated with gelatinization of amylopectin shifted to a higher temperature, and became narrower and deeper after annealing at 50 °C; however the conclusion temperature and enthalpy of gelatinization were similar. The ordered structures of amylopectin, formed by a varying number of links by hydrogen bonds, were cleft at the gelatinization temperature. Model calculation suggested that more links (N) would be generated in each ordered amylopectin region, and the number of ordered regions (M) would be reduced by annealing at a higher temperature. However, the total number of links in amylopectin, represented by the product (N×M), was similar for cereal starches and only slightly increased for potato starch.