Study on Preparation of Weak, Bitter-tasting Protein Hydrolysate by Immobilized Protease

Objective To prepare weak,bitter-tasting protein hydrolysate by immobilized protease.Methods The neutral protease(NP) and Protamex(PM) were covalently immobilized on glutaraldehyde-pretreated chitosan.The immobilized protease was used to catalyze the hydrolysis of casein at 50 ℃.Results The activity recovery for the immobilized neutral protease(INP) and the immobilized Protamex(IPM) was 59.9 % and 35.0 %,respectively.The activity of INP and IPM remained 70.0 % and 79.8 % respectively after repeated usage for 10 times(10 h/time).The degree of hydrolysis(DH) for the IPM-catalyzed hydrolysate and the INP-catalyzed hydrolysate was 9.4 % and 26.5 %,with the bitterness degree of 4 and 2,respectively.The DH and the bitterness degree for the INP-catalyzed hydrolysate were as high as those for the free PM-catalyzed hydrolysate.Conclusion The degree of hydrolysis and the bitterness degree of the weak,bitter-tasting protein hydrolysate prepared by immobilized protease can be good enough to fulfill the quality requirement for the food protein hydrolysate.