凝乳酶对牦牛乳硬质干酪成熟期间蛋白降解的影响

Study on proteolysis of yak milk hard cheese effect of milk-clotting enzymes types during ripening period

以新鲜牦牛乳为原料,采用小牛皱胃酶、木瓜蛋白酶和微生物凝乳酶制作硬质干酪,探讨凝乳酶种类对牦牛乳硬质干酪成熟期间蛋白质降解的影响。结果表明:三种凝乳酶牦牛乳硬质干酪成熟过程中,不同凝乳酶牦牛乳硬质干酪在成熟期间蛋白质降解能力存在较大差异,总氮(TN)、p H4.6水溶性氮(p H4.6-SN/TN)、12%的三氯乙酸氮(12%TCA-N/TN)、5%磷钨酸氮(5%PTA-N/TN)含量、游离氨基酸均随成熟时间延长不同程度的增加,蛋白氮和酪蛋白氮逐渐降低,多肽氮呈先升高后下降趋势,且微生物凝乳酶降解牦牛乳硬质干酪蛋白能力显著(p<0.05)高于木瓜蛋白酶和小牛皱胃酶。

The fresh yak milk was as material,calf rennet,microbial rennet and papain was used as milk-clotting enzymes to produce hard cheese. And it was studied that the milk-clotting enzymes types effected on yak milk hard cheese proteolysis during ripening. The results showed that there was a big difference in proteolysis of different milk-clotting enzymes yak milk hard cheese. To some degree,the TN, pH4.6-SN/TN, 12% TCA-Nfl-N, 5% PTA-N/TN and FAA increased gradually with the ripening time. Protein nitrogen and casein nitrogen decreased sequentially decreased. Polypetide nitrogen increased continuously and then decreased.The proteolysis of microbial rennet yak milk hard cheese was significant（p〈0.05） higher than the papain and calf rennet yak milk hard cheese.