凝乳酶在风味发酵乳脂肪含量测定中的应用

Application of Rennet in Determination of Fat Content of Flavored Yogurt

目的:解决含复配增稠剂的风味发酵乳脂肪含量测定过程中,脂肪被酪蛋白钙盐包裹而难以被溶剂萃取,导致脂肪抽提不完全、脂肪含量测定结果偏低的问题。方法:在样品中添加一定量的凝乳酶进行预处理,再按照碱水解法测定样品中脂肪含量。结果:对于脂肪抽提不完全的风味发酵乳样品,按照原有检测方法测得的脂肪含量结果显著低于标签标识值,出现凝胶挂壁现象,且有3个样品低于食品安全国家标准要求。而添加0.1 g凝乳酶于33~36℃保温60 min预处理样品后,测得的脂肪含量与标识值偏差在0~0.08 g/100 g之间。结论:对于含复配增稠剂的风味发酵乳,采用碱水解法测定其脂肪含量前,添加0.1 g凝乳酶在33~36℃条件下保温60min,可以有效改善脂肪抽提不完全导致脂肪测定结果偏低的问题。

Objective:To solve the problem that the fat content of flavored fermented milk containing compound thickener is encapsulated by calcium casein salt and difficult to be extracted by solvent,and the fat extraction is incomplete,resulting in low fat content determination results.Methods:A certain amount of rennet was added to the sample to pretreat the sample,and then the fat content in the sample was determined according to the alkali hydrolysis method.Results:For the flavor fermented milk samples with incomplete fat extraction,the fat content measured according to the original detection method was significantly lower than the label identification value,and gel wall hanging phenomenon occurred,and three samples were lower than the requirements of the national food safety standard.After adding 0.1 g rennet and holding at 33–36℃for 60 minutes,the deviation between the measured fat content and the labeled value was between 0.00–0.08 g/100 g.Conclusion:Before alkali hydrolysis was used to determine the fat content of flavored fermented milk with compound thickener,0.1 g rennet was added and kept at 33–36℃for 60 minutes could effectively improve the problem of incomplete fat extraction and low fat determination results.