Effects of different treatments on the antioxidant properties and phenolic compounds of rice bran and rice husk

We investigated the changes of antioxidant activity and bioactive compounds in bran, rice husk and ground rice husk after three different treatments, namely hot-air, far-infrared radiation (FIR), and cellulase, compared with raw samples. Overall, FIR-treated group showed a higher DPPH radical scavenging activities, ferric reducing antioxidant power (FRAP), and total phenolic content (TPC) than did hot-air and cellulase treatments for all samples. A significant increase in α- and γ-tocopherols was found in FIR irradiated rice bran compared to raw bran, while α- and γ-tocopherols in hot-air and cellulase treated rice bran were remained unchanged. Cellulase significantly increased the amount of vanillic acid; however a dramatic decrease of ferulic acid was observed. The contents of γ-oryzanol in cellulase treated ground rice husk were significantly increased. Decreasing particle size in the husk was found to work positively for enhancing antioxidant activities, γ-oryzanol and phenolic compounds.