Effect of noncontinuous rice‒water contact cooking method on the structure and starch digestibility of cooked rice

Conventional rice cooking methods often induce excessive starch gelatinization and rapid digestibility owing to continuous contact with water. To address this issue, we developed a noncontinuous rice–water contact (NRWC) method in which rice alternates contact with water. In this study, the moisture content, texture, microstructure, and in vitro starch digestibility of cooked rice were investigated and compared with those of cooked rice subjected to continuous rice‒water contact (CRWC). The in vitro starch digestibility indicated that the NRWC method increased the content of slowly digestible and resistant starches in cooked rice. Meanwhile, the kinetic constant of NRWC cooked rice (k, 1.4 × 10⁻²–1.8 × 10⁻² min⁻¹) and in vitro starch digestibility were lower than those of CRWC cooked rice (k = 2.0 × 10⁻² min⁻¹). NRWC samples with low moisture content (45.1 %–59.3 %) and high hardness (26.5–10.2 N) have the potential to reduce starch digestibility. From the perspective of morphological properties, the NRWC method was beneficial to maintaining the surface smoothness, internal compactness, starch‒protein framework, and integrity of rice. Collectively, this study provides a new perspective on the cooking method of preparing slowly digestible rice.