Differences in starch structural and physicochemical properties and texture characteristics of cooked rice between the main crop and ratoon rice

Ratoon rice (RR) is characterized by higher production combined with enhanced rice quality. However, limited information is available regarding the mechanism of quality enhancement of RR. In this study, three varieties were used to investigate differences in the components, the fine structural and physicochemical properties of starch, and the textural characteristics of cooked rice between the main crop and RR. Compared to the main crop, RR significantly increased the starch and amylose content, amylose to amylopectin ratio, weight average molecular weight of the starch granule, and fa (DP 6–12) and fb1 (DP 13–24) chain proportions of amylopectin. However, it decreased the amylopectin and protein content, mean diameter and number average molecular weight of the starch granule, and fb2 (DP25-36) and fb3 (DP > 37) chain proportions of amylopectin. This contributed to an increase in branching degree, polydispersity, ΔHgel, Tc-R, ΔHret, and retrogradation percentage, as well as a decrease in the average chain length and polymerization degree of amylopectin and crystallinity degree, and water solubility of RR. These differences might contribute to the increase in hardness and decrease in stickiness of cooked RR.