Comparison of 11 rice bran stabilization methods by analyzinglipase activities

摘要

The production of rice bran oil is severely impeded because of the rapid ranciditycaused by rice bran lipase. Eleven stabilization treatments including 6 heating treatmentsand 5 nonheating treatments were carried out in this research. Lipase activitiesas well as oil colors, oil compositions, and contents of vitamin E and γ-oryzanolafter different treatments were investigated to evaluate the effect of stabilizationand oil qualities. All the treatments had no significant influence (p > .05) on the oilcompositions and γ-oryzanol contents. Among six heating treatments, autoclavinghad the best stabilization effect for 10.73% lipase activity remained and other heatingtreatments held about 30%–35% lipase activities residual except dry heating(68.88%). Heating treatments except steam heating resulted in the significant decreases(p < .05) of oil acid values and significant increases (p < .05) of peroxide values,meanwhile six heating treatments increased oil colors. Among five nonheatingtreatments, ultraviolet irradiation for 18 hr and extreme low temperature (−80°C) for72 hr were found 57.08% and 58.85% lipase activities residual, respectively. Peroxidevalue was significantly increased (p < .05) only by ultrasound. All nonheating treatmentshad little effect (p > .05) on oil acid values and color. In conclusion, ultravioletirradiation might be a potential, convenient, and energy-saving stabilization methodwith high oil quality.