Impact of gamma irradiation pre-treatment before subcritical water extraction on recovery yields and antioxidant properties of rice bran extract

Abstract

Gamma irradiation pre-treatment of defatted rice bran was carried out before protein extraction. The extracted content included rice bran protein (RBP), rice bran protein hydrolysate (RBPH) and rice bran hydrolysate (RBH). The extraction yields and protein recovery increased with irradiation for all extracts, especially RBH, of which the yield and protein recovery increased by 21.2% and 13.8%, respectively. The total phenolic content of RBP and RBH was found to be increased in the irradiation-processed extracts. Gamma irradiation could change the structure of rice bran, increasing the release of bioactive compounds. Antioxidant activities (ABTS, DPPH, FRAP and MIC assays) increased significantly in irradiation-processed extracts. FTIR spectra confirmed that the extracts consisted of protein. The FTIR spectra of the chemical functional groups differed between RBP and RBH. In summary, gamma irradiation pre-treatment increased the extraction yield and total phenolic content and enhanced the antioxidant activity.