Effect of stabilization of rice bran by domestic heating on mechanical extraction yield, quality, and antioxidant properties of cold-pressed rice bran oil (Oryza saltiva L.)

Abstract

The effect of stabilization of rice bran by domestic heating on mechanical extraction yield, quality and antioxidant properties of cold-pressed rice bran oil (RBO) was investigated. The highest extraction yield was found in hot air heating with 5.53 g/100 g bran, followed by microwave heating (4.81 g/100 g bran), roasting (4.77 g/100 g bran) and steaming (3.41 g/100 g bran). Hot air and microwave heating were the most effective methods for stabilization of rice bran (P < 0.05), which provided a low content of acid value (AV) 6.30–6.38 mg KOH/g oil, free fatty acid (FFA) 3.51–3.17% and peroxide value (PV) 11.72–12.13 mg Eqv/kg oil. Microwave and hot air heating stabilized RBO contained a higher content of total phenolic compounds than that of roasting and steaming stabilized RBO (P < 0.05). Hot air heating stabilized RBO had the highest content of gamma oryzanol but these were not significantly different in microwave and roasting stabilized RBO (P > 0.05). In conclusion, the stabilization of rice bran by domestic heating could be applied to RBO extraction prior to pressing to improve oil extraction yield, quality and antioxidant properties of cold-pressed RBO.