采用蛋白质定量方法检测掺假牛乳比较研究

Comparative Study of Methods to Detect Protein Content of Adulterate Milk

研究非蛋白质掺假牛乳样品中的乳蛋白质检测方法。样品用15%三氯乙酸溶液处理牛乳样品,沉淀分离乳蛋白质,通过凯氏定氮法和四种分光光度法对液态乳中添加尿素和三聚氰胺常见掺假物进行检测比较研究。结果表明,凯氏定氮法、双缩脲比色法、Folin-酚试剂法、BCA法检测牛乳中掺入不同比例尿素溶液蛋白质含量,结果不受尿素溶液的影响,准确度高。对于牛乳中掺入三聚氰胺溶液,三氯乙酸结合凯氏定氮法检测相对误差较大,而三氯乙酸结合双缩脲比色法、Folin-酚试剂法、BCA法检测结果不受三聚氰胺溶液影响,准确度高。考马斯亮蓝法测定牛乳中掺入尿素溶液和三聚氰胺溶液相对误差均很大。

Research methods to detect protein content of adulterate milk. Process milk samples with 15% trichloroacetic acid and solution to separate the milk protein precipitation, then test urea and melamine by kjeldahl and four kinds of speetmphotomelric method. The results showed that the protein content of samples which were incorporated with different concentrations urea solution, detected by kjeldahl, Biuret eolofimetry, Folin phenol reagent and BCA method, was not affected by urea and had high accuracy. The determination of milk incorporated with melamine, trichloroacetic acid combined with kjeldab_l had a bigger relative error. But trichloroaeetic acid combined with other three methods, the results was not affected by melamine and had high accuracy. Coomassie brilliant blue can not accurately determine milk that incorporated urea and melamine.