Comparison of antioxidant activities of rice bran extracts by different extraction methods

The objective of this study was to determine the antioxidant activities of rice bran extracts by three different extraction methods. Rice bran was extracted by solvent extraction, saponification extraction, and supercritical fluid extraction. The antioxidant activities of the rice bran extracts were determined based on ABTS and DPPH radical scavenging activities, reducing power, and lipid peroxidation inhibitory activity. The unsaponifiable matter (USM) extracted by the saponification method showed higher ABTS (671.7 mg Trolox equivalent antioxidant capacity (TEAC)/g) and DPPH (330.7 mg TEAC/g) radical scavenging activities as well as reducing power (A₇₀₀=1.14) than those of the solvent extract (ME) and supercritical fluid extract (SFE). Inhibitory effect on lipid peroxidation was higher in USM (68.7%) and SFE (75.4%) compared to ME (47.8%). USM indicated relatively higher antioxidant activities compared with those of SFE and ME. These results show that the saponification method for extraction of USM from rice bran extracted was the most effective method for enhancement of antioxidant activity. In addition, these extracts from rice bran could be used as functional ingredients in the food industry.