Relationships between degree of milling and loss of Vitamin B, minerals, and change in amino acid composition of brown rice

Abstract

The effects of the degree of milling (DOM) on amino acid composition, thiamine, riboflavin, phytic acid (PA), and mineral (Mg, Fe, Zn, Mn, Cu, Ca, Se, and Pb) contents of japonica Xinfeng 2 and indica T-You 15 brown rice were investigated. Almost all amino acids slightly decreased as DOM increased. Quadratic and linear relationships were observed between DOM and milling time at 0–30 s and 30–100 s, respectively. Thiamine and riboflavin content decreased linearly as DOM increased. Approximately 57.6–65.4% of thiamine and 40.3–45.7% of riboflavin were removed after 30 s of milling (DOM = ca. 9%). Considerable losses were observed for PA, Mg, Mn, Fe, and Pb during milling (DOM = ca. 9%), whereas the losses of Ca, Cu, Zn, and Se were relatively lower. In addition, the linear correlations of Mg, Mn, Pb, and Fe levels with PA concentration were revealed. These results indicate that DOM should be supervised to improve nutrient utilization and appropriately control toxic metal contamination.