Antioxidant potential of solvent-macerated rice bran extracts prepared with various pretreatments

Rice bran is a potent byproduct of rice milling. Rice bran extract (RBE) has varied antioxidant properties depending on extraction technique. However, solvent maceration with hydrolysis pretreatment is rarely used to determine the RBE potency. This study aimed to determine the appropriate pretreatment method and rice bran:solvent ratio to maximize the quality of RBE, including yield, visual appearance, and antioxidant activity. Pretreatment was carried out with hydrolysis at pH 1, 3, and 5 and compared with no hydrolysis. The best results from pretreatment became the basis for maceration with various ethanol solvent:rice bran ratios (5:1; 6:1; 7:1). Yield, visual appearance, and antioxidant activity are parameters that determine the RBE quality. This study shows extract without hydrolysis had a clearer appearance and high DPPH scavenging activity (70.77%). After maceration, the solvent:rice bran ratio of 7:1 produced the best quality, with a fairly high yield (6.72%), a total phenolic content of 65.97 μg GAE/g RBE, and a higher DPPH scavenging of 75.93%. In the IC50 measurement, the RBE activity was classified as very low at 68,700 μg/mL. These findings indicate that RBE has considerable potential in DPPH scavenging but has a fairly low phenolic content resulting weak antioxidant activity.