【摘要】 比较凯氏定氮法、考马斯亮蓝法和福林酚法测定奶粉蛋白含量的差异,研究了不同种类的非蛋白含氮物(尿素、三聚氰胺、甘氨酸和水解蛋白)、不同添加量(0%、0.5%、1%、2%和10%)对考马斯亮蓝法测定奶粉蛋白含量的影响。实验结果为,考马斯亮法所测蛋白含量与凯氏定氮法相近,福林酚法测定的结果显著高于凯氏定氮法;添加不同比例的4种非蛋白含氮物均对考马斯亮蓝法测定蛋白含量的结果没有影响,随着添加比例的增加,奶粉氮含量的理论值逐渐增大,而测定值没有显著变化。实验结果表明,考马斯亮法可排除添加非蛋白含氮物对奶粉真蛋白含量测定的影响,可以快速、准确的测定奶粉真蛋白含量。更多还原

【Abstract】 The protein content in milk powder with Kjeldahl nitrogen method,Coomassie brilliant blue method and lowry method were compared,and the effects of adding urea,melamine,glycine and hydrolyzed protein with different content(0%,0.5%,1%,2% and 10%) in mill powder on the protein content determined with coomassie brilliant blue method were studied.The protein content determined with coomassie brilliant blue method was similar to that determined with Kjeldahl nitrogen method,protein content determined with lowry method was significantly higher than that determined with Kjeldahl nitrogen method.The addition of non-protein nitrogen compound had no significant effects on the protein content determined with coomassie brilliant blue method.The theoretical data of nitrogen content in milk powder increased with the addition content of non-protein nitrogen compound,but the determined data had no significant changes.Those results indicate that coomassie brilliant blue method can prevent the interference of the addition of non-protein nitrogen compound on true protein determination,and can determine the true protein content in milk powder quickly and accurately.更多还原