Effect of Degree of Milling on the Nutrition and Eating Quality of Brown Rice

To achieve high-quality brown rice with balanced nutritional composition and eating quality, the Suijing 18 rice variety was employed as raw material in this study, through which the effects of varying milling degrees on both nutritional components and eating quality of brown rice were systematically analyzed. The dehulled rice was milled to varying degrees (0%, 2%, 4%, 6%, 8%, and 10%), producing brown rice samples with corresponding milling levels. Changes in residual bran rate, vitamin content, amino acid content, and eating quality parameters (e.g., taste score) were systematically analyzed across different milling degrees, with Suijing 18 polished rice being utilized as the control group. Based on this, a Pearson correlation analysis was systematically conducted to evaluate the relationships between the eating quality of brown rice and its nutritional composition, cooking quality, and other indicators. Results showed that compared to Suijing 18 polished rice, brown rice exhibited a significantly higher residual bran rate (P<0.05), while both its nutritional composition (including vitamins and amino acids) and taste scores demonstrated gradual declines. At a milling degree of 4% (residual bran rate 60%), brown rice retained 88.58% protein, 80.03% vitamin B1, and 62.07% lysine, accompanied by a taste score of 70. The cooked rice exhibited moderate texture with characteristic aroma. When milling degree increased to 10%, the taste score reached 80 (P>0.05) vs polished rice, while nutritional components remained significantly higher (P<0.05) than polished rice. Correlation analysis revealed that the milling degree of brown rice demonstrated strong positive correlations (r>0.95) with taste score, viscosity, elasticity, water absorption rate, and expansion rate, while showing significant negative correlations (r≥0.96) with residual bran rate and protein content. Therefore, improving indicators such as residual bran rate and protein content can further enhance the eating quality of brown rice.