Annealing treatment of amylose and amylopectin extracted from rice starch

Annealing behavior of amylose and amylopectin was unclear. In this work, high purity amylose and amylopectin were extracted from rice starch, and structural properties of the retrograded rice starch, amylose, and amylopectin before and after annealing treatment were explored. It was found that the purity of the amylose and amylopectin was 95.64% ± 2.69% and 94.98% ± 0.97%, respectively. Their molecular weight was (2.93 ± 0.21) × 10⁶ Da and (5.90 ± 0.13) × 10⁷ Da, respectively. Besides, the relative crystallinities and ratios of 1047 cm^-1/1022 cm^-1 of the retrograded rice starch and amylose were significantly increased by annealing treatment, while that of retrograded amylopectin did not change. These results clarified that amylose was more sensitive to annealing treatment than amylopectin, and amylose was more responsible for annealing of starch than amylopectin. The findings contributed to a better understanding of the annealing behavior of starch.