Impact of the degree of starch gelatinization on the texture, soaking, and cooking characteristics of high amylose rice: an experimental and numerical study

The degree of gelatinization (DG) of rice starch during paddy parboiling is associated with its physicochemical, water absorption, and cooking properties. The selection of rice with a proper DG that fulfills consumer preferences and matches the quality requirements of rice-based product industries can be guided by empirical models. This study aims to establish the empirical correlation explaining the impact of varying DG on rice properties. Paddy was open-parboiled to varying DG (5-65%), studied for its physicochemical, water absorption, and cooking properties, and empirically modeled for its changes with varying DG. In addition, the water absorption properties of rice with varying DG and the respective changes in hardness and cooking time were also studied and modeled. The empirical relationships developed from the experimental findings relate to rice's physicochemical, water absorption, and cooking properties for varying DGs. The changes in hardness, apparent amylose content, cooking properties, and whiteness index with increasing DG followed polynomial and power law equations. The moisture gained during the soaking of milled rice with varying DG followed the Weibull and Peleg model. With the increase in soaking time, the rice's hardness and cooking time decreased, following the first-order kinetics. The results suggest that the established empirical models can be used to forecast the physicochemical, soaking, and cooking attributes of rice with varying DGs that significantly impact rice and rice-based product development.