Effects of protease and hydrolysis conditions on the properties of casein hydrolysates

Casein was hydrolyzed by alcalase,papain,trypsin and bromrlain,respectively,which showed that casein was hydrolyzed to the maximum degree by alcalase.Also molecular weight distribution of the casein hydrolyzed by various proteases,showed great difference when compared under the same DH.Then Alcalase was chosen for the next research,casein hydrolysates with DH 8% and 12% were prepared by p H- stat method,DPPH scavenging ability and TCA solubility were determined.The result showed that DPPH scavenging ability of DH 8% and DH 12%hydrolysates varied from 32.76% to 34.02% and 39.87% ~41.02%,respectively,the value interval of TCA solubility of DH 8% and DH 12% hydrolysates were 58.98% to 60.43% and 69.69% ~ 70.34%,respectively. According to the result of analysis of variance,for the given enzyme- substrate system,the properties of casein hydrolysates with the same DH were independent of variations hydrolysis conditions( hydrolysis temperature and enzyme / substrate ratio). The molecular weight distribution of HPLC confirmed that hydrolysates molecular weight were similar with each other when compared at the same DH.