Relative Free Fatty Acid Formation and Lipid Oxidation of Commercially Milled Unseparated, Head, and Broken Rice

This study was conducted to determine the relative rate of free fatty acid (FFA) formation and lipid oxidation of unseparated (head and broken), head, and broken rice and the effect of water washing on broken rice lipid quality. A regression model was developed with surface FFA or conjugated diene (CD) content versus incubation time to determine the rates of FFA formation and lipid oxidation. The surface lipid contents of unseparated, head, and broken rice were 0.40, 0.38, and 0.50 % of rice, respectively. The FFA formation during storage showed three phases; an initial rapid formation, followed by a period of very little or no formation, and finally a phase of gradual formation. In contrast CD formation initially showed a slow increase but later increased gradually with storage time. The relative rates of FFA and CD formation of unseparated, head, and broken rice were 0.0028, 0.0027, 0.0036 and 0.192, 0.188, 0.377, respectively.