LIMITED HYDROLYSIS OF RICE PROTEIN ISOLATE AND STUDY ON ITS FUNCTIONAL PROPERTIES

Four commercial proteases were evaluated when applied to hydrolyze rice protein isolate. Alcalase has apparently higher efficiency than other protease and its optimal hydrolyzing conditions are Enzyme-to-substrate ratios1%, protein concentration 6 %, pH8.5, temperature 50 ℃-60 ℃. Ultrasound of 40 kHz, 40 W-100 W was applied to facilitate protein hydrolysis and an auxiliary effect was discovered only at the beginning of the hydrolysis process. Rice protein hydrolysates with DH from 2 % to 10 % was obtained by using Alcalase. Its solubility imporved as the DH increased, but bitterness appeared when DH reached 8 %. Foam stability of rice protein hydrolysates increased as DH grows, but foaming capacity did not improve.