混料设计优化牦牛“曲拉”凝乳酶干酪素的工艺及产品的性质分析

Optimization of coagulation process for yak Qula rennet casein by mixture design and the analysis of the products

为提高牦牛产业的附加值,以牦牛乳提取酥油后进行凝固沉淀,再经自然发酵、风干而成的蛋白质含量丰富的产品“曲拉”为原料,采用胃蛋白酶、木瓜凝乳酶和酵母凝乳酶复配成混合凝乳酶,通过单因素实验和混料设计对凝乳干酪素的制备工艺进行研究,并对干酪素的理化性质、红外光谱特性、热力学性质进行分析。结果表明,混合酶质量分数1%(其中胃蛋白酶∶木瓜凝乳酶∶酵母凝乳酶的质量比为0.60∶0.18∶0.22),在pH 6.3、45℃、添加质量分数CaCl 21%条件下,凝乳30 min,出品率为80.35%。混合酶法制备干酪素的理化性质、红外光谱特性和热力学性质与小牛皱胃酶干酪素差异不显著,而且符合GB31638—2016要求。

In order to improve the added value of the yak industry,product named Qula containing abundant protein was made from yak milk after fat removing,coagulating and precipitating,and natural fermentation and drying.The mixed chymosin consisting of pepsin,papaya chymosin and yeast chymosin was used as the coagulant to prepare“Qula”rennet casein.The coagulation process of“Qula”rennet casein was optimized by single factor tests and mixture design.The physicochemical properties,infrared spectrum characteristics and thermodynamic properties of casein were analyzed.The results showed that the product yield of 80.35%was obtained under the optimum extraction conditions of 1.0%mixed chymosin comprising pepsin,papaya chymosin and yeast chymosin(proportion of 0.60∶0.18∶0.22),1%CaCl 2(mass proportion),pH 6.3,45℃,and curding for 30 min.The physicochemical properties,infrared spectrum characteristics and thermodynamic properties of casein prepared by mixed chymosin were not significantly different from those of calf rennet,meeting the requirements of GB 31638—2016.