人为添加三聚氰胺液态乳中蛋白质含量测定方法的研究  

Research on the methods of protein determination after added melamine in milk

作　　者：刘莹[1] 傅泽田[2] 侯彩云[1] 邱元亨[3] 路勇[4] 

机构地区：[1]中国农业大学食品科学与营养工程学院,北京100083 [2]中国农业大学工学院,北京100083 [3]农业部乳品质量监督检验测试中心,天津300381 [4]北京市食品安全监控中心,北京100041

出　　处：《中国农业大学学报》2009年第2期22-26,共5页Journal of China Agricultural University

基　　金：国家"863"项目资助(20060110Z2005);科技部星火计划项目(2007EA600004)

摘　　要：用GB/T5413.1《婴幼儿配方食品和乳粉蛋白质的测定》、GB/T 21704—2008《乳与乳制品中非蛋白氮含量的测定》和ISO8968-5:2001/IDF 20-5:2001《Milk-Determination of nitrogen content-Part 4:Determination ofprotein nitrogen content》3种国内外现行标准方法,对液态乳中添加三聚氰胺后的蛋白质、非蛋白氮和蛋白氮含量进行了测定,并与双缩脲比色法和三氯乙酸-双缩脲比色法测定的蛋白质含量进行了比较。结果表明:利用前3种标准方法分别测定液态乳添加三聚氰胺后的蛋白质、非蛋白氮和蛋白氮含量,误差率依次为46.60%、93.00%和52.70%;利用双缩脲比色法和三氯乙酸-双缩脲比色法测定液态乳添加三聚氰胺后的真蛋白含量,误差率分别为2.87%和2.22%,比上述3种标准方法更为准确,说明它们既可以排除添加尿素、甘氨酸等非蛋白氮的干扰,又可以准确测定液态乳中的蛋白质含量;其中三氯乙酸-双缩脲比色法比双缩脲比色法的适用性更广。The contents of protein, non-protein nitrogen and pro!ein nitrogen were determined using GB/T5413.1 ,GB/T 21704-2008 and ISO 8968-5：2001/ IDF 20-5：2001 methods after adding melamine in milk, and the results were compared with the standard methods, the Biuret Spectrophotometry methord （B method） and Trichloroacetic acid and Biuret Spectrophotometry method （T ＋ B method）. It is shown from the results that the error rates were 46.60%, 93.00% and 52.70% respectively for the methods of GB/T5413, GB/T 21704 - 2008 and ISQ 8968-5：2001 to determine the content of protein, non-protein nitrogen and protein nitrogen in melamine added milk, while the error rates of B method and T＋ B method were 3.00% and 3.05% respectively. The B method and T＋ B method could determine the content of protein after adding Urea and Glycin. Compared with the B method, the T ＋ B method can determined the content of protein accuratelyafter adding hydrolysatum in milk.

关 键 词：液态乳 蛋白质 标准方法 双缩脲比色法 三氯乙酸双缩脲比色法 

分 类 号：TS252.7[轻工技术与工程—农产品加工及贮藏工程]