Effects of warming on starch structure, rice flour pasting property, and cooked rice texture in a double rice cropping system

Background and objectives Climate warming has significant effects on rice quality. However, the effects of warming on starch structure, rice flour pasting properties, and cooked rice texture are unclear in double rice cropping systems. Therefore, a free-air temperature increase experiment was conducted with two indica rice cultivars. The objectives of this study were to explore the changes in rice flour pasting properties and cooked rice texture under warming conditions and their relationships with starch structures. Findings Under warming conditions, rice starch had a lower amylose content (Peak 3) and proportion of long amylopectin branch chains (B3 chains) but a higher proportion of short amylopectin branch chains (A chains and B1 chains), amylopectin branching degree, relative crystallinity, ratio of 1045/1022 cm(-1), and swelling power. Compared to the control treatment, warming significantly increased the peak viscosity, breakdown, and pasting temperature but decreased the setback of rice flour. Moreover, the hardness of cooked rice was significantly decreased, while its stickiness was significantly increased under warming conditions. Conclusions The changes in starch molecular structures resulted in lower hardness and setback but a higher stickiness, peak viscosity, breakdown, and pasting temperature of cooked rice or rice flour, which means better eating quality and worse cooking quality of double-cropped indica rice under climate warming conditions. Significance and novelty These findings are expected to provide important information for improving rice cooking and eating quality and developing the rice industry under future climate warming conditions.