Establishment of a Comprehensive Quality Evaluation Model for Japonica Rice With Different Degrees of Milling

Japonica is considered one of the better tasting varieties, so it is important to balance the quality and taste of japonica rice produced by moderate processing. This study analyzed the changes in bioactive components, heavy metal elements, and sensory quality of northern japonica rice after gradient milling, and constructed a comprehensive quality evaluation model for japonica rice with different degrees of milling. The results showed that as the degree of milling (DOM) increased from 0% to 10%, the bioactive components in japonica rice decreased, with dietary fiber (3.67%-0.71%), total phenols (0.73-0.24 mg/g), and vitamin B₂ (0.063-0.025 mg/kg) being markedly reduced. Moreover, heavy metal elements such as inorganic arsenic, cadmium (Cd), and mercury also showed a downward trend. In sensory analysis, the taste quality of japonica rice with different degrees of milling showed an upward trend. Correlation analysis was further used to discuss the comprehensive indicators of gradient milled japonica rice, and the results showed that there were varying degrees of correlation among the indicators. Therefore, principal component analysis (PCA) was used to remove the overlapping information, and three principal components were extracted with a cumulative contribution rate of 91.67%. This corresponds to the results of cluster analysis, which divided the rice into three categories based on indicators and varieties. Finally, we obtained the edible quality evaluation model of japonica rice with different degrees of milling as Z = 0.81F ₁ + 0.13F ₂ + 0.07F ₃. Simultaneously, we determined that the comprehensive quality of japonica rice with a milling accuracy of 9% (J-9) was the highest in gradient milling, which provided a theoretical basis for moderate processing of japonica rice.