EVALUATION OF ANTIOXIDANT ACTIVITY AND POLYPHENOL PROFILE IN DIFFERENT RICE BRAN FRACTIONS

Rice bran, an abundant by-product of rice processing, is a rich source of phenolic compounds with potential for the development of antioxidant ingredients for the food industry. Taking advantage of this agro-industrial waste represents a promising strategy to add value to a material that is currently underutilized. This study aimed to compare the antioxidant activity and identify the polyphenols present in rice bran samples from two suppliers in the state of São Paulo (A and B). In order to identify the fraction with the highest concentration of polyphenols and antioxidant activity, the samples were subjected to crushing and subsequent granulometric classification in 45 mesh tamis, resulting in four fractions called A-retentate, A-sifted, B-retented and B-sieved. Then the samples were defatted with hexane for 1 h in ultrasound and the defatted extract was then used to determine the total phenolic content (Folin–Ciocalteu), antioxidant activity by DPPH (IC50 and IAA) and polyphenols by HPLC-DAD. The total phenolic contents, determined by Folin–Ciocalteu, differed significantly between the samples (ANOVA/Tukey, p<0.05), in descending order (in μg/mL EAG): B-retentated (166.46) > B-sifted (123.71) > A-sifted (112.14) > A-retentated (101.08). For antioxidant activity by DPPH, the IC₅₀ values (μg/mL) were: B-retentated 501, A-retentated 565, A-sifted 600, B-sifted 724; and only B-sieved differed significantly from the other samples