INFLUENCE OF ENZYMATIC HYDROLYSIS CONDITIONS ON THE ANTIOXIDANT ACTIVITY OF PROTEIN HYDROLYSATE PREPARED FROM THAI RICEBERRY

Abstract

This work was carried out to optimal hydrolysis condition for producing riceberry protein hydrolysate with high antioxidant. Hydrolysis of the isolated proteins from riceberry was performed using alcalase, flavourzyme and bromelain. Degree of hydrolysis (DH), total phenolic content and antioxidant activities of hydrolysates by alcalase (IRA), flavourzyme (IRF) and bromelain (IRB) were investigated. By comparison, IRF exhibited higher degree of hydrolysates and antioxidant activities than IRA and IRB. Response surface methodology (RSM) revealed that the optimal condition was 10% flavourzyme® and hydrolysis time for 6 h, which resulted in a 56.36 ± 2.05% of 1,1-diphenyl-2- picrylhydrazyl (DPPH•) radical-scavenging activities and a 55.51 ± 0.16% of 2,2’-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS•+) radicalscavenging activities. Moreover, antioxidant activity of IRBs was significantly higher compared to those of the hydrolysates produced from isolated brown rice protein (Khao Dawk Mali 105). Results suggested that high antioxidant activities of IRB could contribute to bioactive peptides and phenolic compounds. Riceberry protein hydrolysates may be further used as healthpromoting ingredients in food industry.