Starch Digestibility in “Double‐High” Rice: Characteristics and Pasting and Textural Determinants

Background and Objectives Amylose and protein are key factors influencing starch digestibility in rice. This study aimed to characterize the starch digestibility of “double‐high” rice varieties—defined by concurrently high amylose and protein contents—and to identify the pasting and textural properties underlying their digestibility patterns. To achieve this, three “double‐high” rice varieties were compared with three rice varieties containing relatively lower contents of both amylose and protein. Findings The three “double‐high” varieties had average amylose and protein contents of 27.3% and 9.7%, respectively—approximately 120% and 38% higher than those of the other three varieties—and exhibited a 65% longer active digestibility duration along with a 44% lower glucose production rate. While correlation analysis showed that these digestibility indicators were significantly related to both amylose and protein contents, partial correlation analysis demonstrated that the effects were mainly driven by higher amylose content rather than protein content. Compared with the other three varieties, the three “double‐high” varieties had 16%–62% lower peak and breakdown viscosities, alongside 34%–194% higher trough, final, and setback viscosities. They also showed 33%–212% increases in hardness, cohesiveness, resilience, and chewiness. Conclusions The “double‐high” varieties exhibited slower starch digestibility, which was mainly attributed to their higher amylose content rather than higher protein content. This slower digestibility pattern was closely linked to distinctive flour viscosity properties and a more compact cooked rice texture. Significance and Novelty These findings provide insight into the physiochemical characteristics of “double‐high” rice and inform the development of varieties with slower starch digestibility.