Medium milled processing and quality analysis of Jihong No.6 rice

To explore the effects of different processing technologies and pressure gear combinations on the quality of Jihong No.6 rice, Jihong No.6 japonica brown rice was used as the raw material. After being roughened with a laboratory abrasive emery mill, different metal mills and pressure gear combinations were used to study the processing and quality analysis of the medium milled rice. The results showed that when the milling pressure gear was 4.75, (4+1.75), (4.25+1) and (3.5+2+1.25), the bran retention of rice were 2.03%, 2.15%, 2.23% and 2.20%, respectively, and the embryo retention rates were 19.00%, 19.33%, 19.67% and 16.67%, respectively. All these values met the quality requirements for "medium milled" rice as specified in GB/T 1354—2018, indicating that different whitening processes could all produce medium milled rice. By analyzing processing quality, eating quality, and other factors, the optimal processing conditions for Jihong No.6 rice were determined to be the pressure setting combination of (3.5+2+1.25) in a three-pass iron roller milling process. Under the optimal processing conditions, the bran retention of hull and embryo retention rate of the rice samples were 2.20% and 16.67%, respectively. The broken rice rate decreased by 8.85% compared with well-milled rice (with a bran retention of hull percentage of 0.90%). Compared with brown rice, the whiteness value increased by 71.62%. Compared with the best-tasting polished rice (with a bran retention of hull percentage of 0.90%), fat, protein and ash increased by 97.37%, 1.57% and 17.14%. The fat content was significantly correlated with the rate of embryo retention, and was significantly correlated with the degree of bran retention. The protein content was significantly correlated with the rate of embryo retention and the degree of bran retention. Compared with the well milled rice (with a bran retention of hull percentage of 0.90%), the medium milled rice contains more fat, inorganic salts, and other substances, making it more nutritious.