Physicochemical properties, fatty acid compositions, bioactive compounds, antioxidant activity and thermal behavior of rice bran oil obtained with aqueous enzymatic extraction

Abstract

Rice bran as a by-product of rice processing can be used to produce oil. Aqueous enzymatic extraction (AEE) of rice bran oil (RBO) was performed in this study. The physicochemical properties, fatty acid compositions, bioactive compounds, antioxidant activity and thermal behavior of AEE-extracted oil (AEEO) were evaluated and compared with those of Soxhlet-extracted oil (SEO). It was found that iodine value and saponification value in the AEEO were higher than the SEO. AEEO with lower acid value and peroxide value was considered to be a high quality. The contents of wax and phospholipid in AEEO were lower, which could simplify the refining steps. Additionally, AEEO exhibited a higher content of unsaturated fatty acids (76.31%), sum of tocopherols and tocotrienols (1004 mg/kg), sterols (7749 mg/100 g), squalene (2962 mg/kg), oryzanol (2.43 g/100 g). The antioxidant activity of AEEO (EC50 = 5.52 mg/mL) was better than that of SEO (EC50 = 8.66 mg/mL). Moreover, AEEO was found to have lower crystallization and melting points. Scanning electron microscope (SEM) results showed the destruction of cell walls and the decrease of substances in the cell by AEE. Overall, the present results showed the improvement in the quality of the AEEO for green extraction of RBO.