Evaluation of the Starch Properties of Rice Grains and Enzymatic Digestibility of Steamed Rice During Sake Brewing Based on the Swelling Behavior of Rice Grains During Heating

ABSTRACT Background and Objectives The physicochemical properties of cereal starch affect food quality and processing properties, for example, the properties of rice starch influence the suitability of rice for sake (traditional Japanese alcoholic beverage) production. This study reports a convenient method for evaluating the starch gelatinization and retrogradation properties of rice grains and enzymatic digestibility of steamed rice to determine the suitability of japonica rice for sake brewing. Findings The swelling properties of polished rice grains were observed during the heating of nonfloured (whole‐grain) samples. The swelling‐onset temperature and swelling ratio were significantly correlated with the amylopectin side‐chain structure of rice starch, starch gelatinization/retrogradation properties, and enzymatic digestibility of steamed rice under sake production–like conditions. Swelling‐onset temperatures at a swelling ratio of 1.2 were measured for 31 samples with a polishing ratio of 70%, and the strength of the corresponding correlations ( R 2 = 0.79–0.93) were comparable with those observed for gelatinization and pasting temperatures (determined by DSC and rapid visco analysis, respectively). Conclusions The starch properties and enzymatic digestibility of multiple steamed rice samples could be rapidly evaluated without flouring. Significance and Novelty The method facilitates the evaluation of rice used for sake brewing and analysis of starch properties in a wide range of food industries.