Evaluation of the antioxidant activity of rice bran extracts using different antioxidant assays

In the present work the antioxidant activity of different solvent (100% methanol, 80% methanol, 100% acetone, 80% acetone) extracts of rice bran was evaluated following different antioxidant assays and using sunflower oil as oxidation substrate. The rice bran extracts were evaluated from the estimate of % inhibition of peroxidation in linoleic acid system, total phenolics content (TPC) and loss of β-carotene in a linoleic acid system. Additionally, crude concentrated rice bran extracts were added into the sunflower oil samples and stored under ambient conditions. The extent of oxidative deterioration was followed by the measurement of peroxide-, p-anisidine-, conjugated diene-, and triene- values. The general order of antioxidant efficacy of rice bran extracts as determined by various antioxidant assays was 80% methanolic extract > 100% methanolic extract > 80% acetone extract > 100% acetone extract. The results of the present comprehensive analysis demonstrate that rice bran extracts of the Super Kernel variety indigenous to Pakistan are a viable source of natural antioxidants and might be exploited for functional foods and nutraceutical applications.