Examination of Antioxidant Activity and Development of Rice Bran Oil and Gamma-Oryzanol Microemulsion

Abstract

The aims of this study were to examine the antioxidant activity and formulate rice bran oil and gamma-oryzanol product. Two methods of antioxidant activity examination were DPPH radical scavenging assay and Ferric Reducing Antioxidant Potential (FRAP) assay. According to our study, the outcome of free radical scavenging properties of gamma-oryzanol was demonstrated in term of Trolox equivalent antioxidant capacity (TEAC). For DPPH assay, TEAC values were of 0.0015-0.0206 mmol/g when the concentrations were 0.0625-1.0000 mg/ml. For FRAP assay, TEAC values were of 0.0054-0.0272 mmol/g when the concentrations were 0.0680-1.0910 mg/ml. While the linear correlation between TEAC and log concentration was determined as R2 = 0.9929 and 0.9975 respectively. The outcomes of free radical scavenging properties of rice bran oil, for DPPH assay, TEAC values were of 0.0059-0.0214 mmol/g when the concentrations were 8-40 mg/ml. While FRAP assay, could not examine the antioxidant activity because of the immiscibility between reagent and rice brain oil. Then microemulsion was formulated using rice brain oil and gamma-oryzanol as an active antioxidant, Cremophor and Span 80 as a surfactant and absolute ethanol as a cosurfactant. The developed formulation had high antioxidant activity with no skin irritation.