Abstract: This study investigated the difference in the quality of parboiled rice processed from rice with different storage times in order to provide a basis for the selection of raw materials for parboiled rice production. Forty samples of Indica rice and 40 samples of Japonica rice with different storage times were selected to process parboiled rice. Then, the cooking characteristics and visual appearance of parboiled rice, and the eating quality and texture parameters of cooked parboiled rice were determined. The quality parameters of parboiled rice were analyzed by descriptive statistical analysis, analysis of variance and principal component analysis. Clustering analysis was used to investigate the suitability to make parboiled rice. The results showed that the water-absorbing rate and volume swelling rate of parboiled rice were increased with increasing storage time of raw rice, and the average water-absorbing rates of parboiled Indica and Japonica rice stored for four years were increased by 49.1% and 35.9%, and the swelling volume rates were increased by 70.6% and 66.6%, respectively, when compared with the counterparts stored for one year. There was no significant change in the pH, iodine blue value or solid content of rice soup. For both rice varieties, the total sensory score of parboiled rice decreased, the color became darker, and the visual appearance deteriorated; the palatability and taste of cooked parboiled rice worsened. The sensory quality of parboiled Indica rice was better than that of parboiled Japonica rice. No significant change was observed in all texture parameters except for an increase in hardness and chewiness for both cooked parboiled rice and a decrease in adhesiveness for cooked Japonica rice. On the basis of sensory quality evaluation, the analysis of texture parameters was introduced to comprehensively evaluate the quality of parboiled rice, and principal component analysis was used to construct a mathematical model for the evaluation of parboiled rice quality. Then, clustering analysis of the comprehensive scores was performed for quality classification, and the number of samples in each storage year was counted, which confirmed that Indica rice was more suitable for parboiled rice processing than Japonica rice, and parboiled Indica rice stored for one or two years had better quality than that with longer storage times.

Key words: rice; parboiled rice; cooking property; eating quality; raw material suitability