Gamma radiation vs high pressure pretreatment on physicochemical characteristics of rice bran hydrolysate.

This study investigated the effect of using gamma radiation and high-pressure processing as pretreatment, to consider the structural and amino acid composition changes in rice bran hydrolysate (RBH). The extraction yield and degree of hydrolysis of the irradiated sample were greater than those of the pressurized and control samples, which radiation at 10 kGy gave 31 % yield. Protein content of the control was the highest at 36.1 %, with 32.4 % in pressurized sample at 500 MPa. Control had the highest concentration of total and branched-chain amino acids, with a value of 25,834 mg/100g. Before and after extraction, the microstructure changed visibly and protein agglomeration can be significantly induced by applying a high-pressure. Therefore, this study showed the potential of using both pretreatment methods prior to enzymolysis extraction, with radiation producing more extract. High-pressure produced more protein content, but neither method produced any difference in amino acid content.