Pretreatment to increase yield and antioxidant activity of γ-oryzanol in rice bran oil

Six pretreatment processes to extract oil from Khao Dok Mali 105 rice bran were tested to assess the effect of the processes on the gamma-oryzanol content and DPPH scavenging activity of the extract. The pretreatment processes consisted of the following: microwave heating (60-110 degrees C), hot air heating (70-180 degrees C), roasting (60-80 degrees C), parboiling (70 degrees C), autoclaving (121 degrees C), and enzyme (amylase) treatment (50 degrees C). The highest amount of oil was obtained by hot air heating (70 degrees C) of 0.27 g/g of dried rice bran, whereas the highest gamma-oryzanol yield was obtained by parboiling 9.8 mg/g of dried rice bran. The highest gamma-oryzanol concentration obtained with a roasting pretreatment (60 degrees C) was 46.9 mg/ml of rice bran