Kinetic analysis of cooking-induced changes and <i>in vitro</i> starch digestibility of cooked parboiled rice (cultivar MR297)

MR297 is a rice cultivar recently developed and widely cultivated in Malaysia. This study investigates the kinetics of hydration, elongation, and textural alterations of parboiled rice MR297 during cooking. It explores correlations between mathematical model coefficients and rice composition, and evaluates in vitro starch digestibility of cooked rice. The hydration, hardness, and elongation ratio kinetics of parboiled MR297, unparboiled MR297, and locally parboiled Malaysian rice were analyzed during cooking for 4, 8, 12, 16, 20, and 24 minutes. The changes were accurately fitted using nine model equations. The Jena–Das and Cubic equations best represented the coefficient variations (R² > 0.98). Analysis examined correlations between basic nutrients of uncooked rice and in vitro starch digestibility of cooked rice with model coefficients. Strong relationships were found between each coefficient and starch fractions—rapidly digestible starch, slowly digestible starch, and resistant starch—based on digestibility. These correlations suggest that rice changes during cooking represent differences in starch fractions. This study provides helpful information to rice manufacturers and food processors of MR297, offering predictive insights for optimizing cooking processes and understanding nutritional transformations.