Effect of refining process on physicochemical parameters, chemical compositions and in vitro antioxidant activities of rice bran oil

In the present work, the effect of refining process on physicochemical parameters (acid and peroxide values), chemical compositions (fatty acid and phytochemical contents) and in vitro antioxidant activities of rice bran oil (RBO) were investigated. The results showed that acid and peroxide values of the test RBOs decreased significantly after the refining process. However, refining did not have significant influence on the fatty acid composition. Besides, phytochemical levels (except tocopherols) and antioxidant activities of the RBO were reduced to a large degree during the refining. Among the steps of RBO refining, neutralization caused the largest losses of phytochemicals and antioxidant activities. According to the correlation analysis, polyphenols were significantly positive correlated with ABTS and ORAC values, while gamma-oryzanol was significantly positive correlated with DPPH and CAA values. Chemometrics was employed to evaluate the certain contribution of phytochemical to the antioxidant activity, and the measures that can be taken to reduce the loss of phytochemical levels in each step of the RBO refining process were also provided.