不同蛋白酶和水解条件对酪蛋白酶解产物性质的影响

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

采用碱性蛋白酶、木瓜蛋白酶、菠萝蛋白酶和胰蛋白酶分别对酪蛋白进行酶解,发现碱性蛋白酶水解酪蛋白的水解程度最大。当酪蛋白经不同的酶水解至相同水解度（DH）时,酶解物的分子量分布存在显著差异。随后选定碱性蛋白酶以考察水解条件对酪蛋白酶解产物性质的影响,采用p H-stat法控制水解过程p H恒定（8.5±0.02）,制备DH8%和12%的酶解产物,分别测定其DPPH自由基清除率,TCA可溶性氮含量,采用SE-HPLC测定分子量分布。结果表明,不同酶解条件下,DH 8%和DH 12%水解产物的DPPH自由基清除率分别为32.76%-34.02%和39.87%-41.02,DH 8%和DH 12%水解产物的TCA可溶性氮含量值分别为58.98%-60.43%和69.69%-70.34%。方差分析显示水解度相同,不同产物的DPPH自由基清除率无显著性差异,TCA可溶性氮含量的结果亦如此（p〉0.05）。HPLC的结果进一步证明尽管水解条件不同,水解至相同DH时,水解产物的分子量分布一致。

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.