真蛋白率在液态奶质量鉴别中的应用

将不同水解度的猪皮水解蛋白添加到液态奶中,通过三氯乙酸-双缩脲法和凯氏定氮法分别测得其真蛋白质量分数和粗蛋白质量分数显著高于空白样品,表明单独的真蛋白质量分数或粗蛋白质量分数难以作为鉴别乳及乳制品中掺假水解蛋白的可靠指标。同时测得其真蛋白率范围在47.98%～59.36%之间,远远低于液态乳的合理真蛋白率范围,表明真蛋白率法可作为鉴别液态乳中是否存在水解蛋白更为有效的一种方法。

Study of the quality identification of the liquid milk using the ratio of true protein

Add hydrolyzed pigskin protein of different hydrolyzing degree into the liquid milk as sample.The content of the true protein and content of the crude protein determined by trichloroacetic acid biuret method and Kjeldahl method respectively are apparently higher than the blank sample,which shows the content of the true protein only and content of the crude protein only can’t identify the quality of the liquid milk.The ratio of true protein of the sample is 47.98%～59.36% which is far lower the reasonable limit.Thus the method of the ratio of true protein is a more efficient method to decide whether there is hydrolyzed protein in the liquid milk or not.