Abstract: The dipeptidyl peptidase-Ⅳ (DPP-Ⅳ) inhibitory activity and physicochemical properties of yak milk casein hydrolysates produced with alcalase, papain and trypsin were investigated. The effect of hydrolysis periods and different proteases on the DPP-Ⅳ inhibitory activity of yak milk casein hydrolysates was assessed by DPP-Ⅳ inhibitory rate. The physicochemical properties of yak milk casein hydrolysates were evaluated by degree of hydrolysis, trichloroacetic acidnitrogen soluble index (TCA-NSI), solubility and ash content. Results showed that the DPP-Ⅳ inhibitory activity of yak milk casein hydrolysate obtained with papain was significantly higher than that of those obtained with alcalase or trypsin at the same hydrolysis period (P < 0.05). The yak milk casein hydrolysate obtained after 0.50 h hydrolysis with papain displayed the highest DPP-Ⅳ inhibitory activity (with inhibitory rate of (53.95 ± 1.57) %), higher extent of hydrolysis degree, and the lowest ash content. The results suggest that peptides with DPP-Ⅳ inhibitory activity can be generated from yak milk casein. The yak milk casein hydrolysate produced by papain may be used as a functional dairy ingredient to develop functional foods.

Key words: yak milk; dipeptidyl peptidase-Ⅳ; degree of hydrolysis

摘要： 以牦牛乳酪蛋白为原料,利用碱性蛋白酶、木瓜蛋白酶和胰蛋白酶制备酪蛋白酶解产物,研究其二肽基肽酶-Ⅳ(dipeptidyl peptidase-Ⅳ,DPP-Ⅳ)抑制活性和理化特性.以DPP-Ⅳ抑制率为指标,研究水解时间和蛋白酶的种类对酶解产物DPP-Ⅳ抑制活性的影响,以水解度、三氯乙酸氮溶解指数(trichloroacetic acid-nitrogen soluble index,TCA-NSI)、溶解性和灰分含量为指标,评价酶解产物的理化特性.结果表明:对于相同水解时间点获得的酶解产物,木瓜蛋白酶酶解产物的DPP-Ⅳ抑制活性显著高于其他2种蛋白酶的酶解产物(P＜0.05).利用木瓜蛋白酶水解0.50 h的酶解产物具有最高的DPP-Ⅳ抑制活性(抑制率可达(53.95±1.57)％)、较高的水解程度以及最低的灰分含量.说明利用蛋白酶水解技术能够使牦牛乳酪蛋白中具有DPP-Ⅳ抑制活性的多肽释放,木瓜蛋白酶酶解产物可作为功能性乳基料用于功能性食品的开发.

关键词: 牦牛乳；二肽基肽酶-Ⅳ；水解度