摘要
我国现行标准GB/T5009.5-2003《食品中蛋白质的测定》中的两种方法"凯氏定氮法"和杜马斯(Dumas)燃烧法是先将样品硝化后测出含氮量,然后根据氮元素与蛋白质换算系数计算蛋白质的含量,如果添加含氮量高的物质,如三聚氰胺,就可以测出较高的"蛋白质含量"。介绍4种直接测定蛋白质的方法:考马斯亮兰法、双缩脲法、Folin-酚试剂法和紫外吸收光谱法,可以避免上述由于添加违规化学物质造成测定蛋白质含量虚高的结果。
According to the current standard of Determination of Protein Content in Food GB/T5009.5-2003 in China,there are two methods to determine the protein content.They are Kjeldahl method of nitrogen determination and Dumas method.Both of the two ways determine the nitrogen content by nitrification firstly and then calculate the protein content according to the conversion coefficient between the nitrogen and protein.If such high nitrogen content chemical substance as Melamine is added to the food,the protein content will be higher accordingly.In this peper,four direct determination methods were introduced including Bradford method,Biuret method,Lowry method and ultraviolet absorption spectrometry.These methods are more precise to determine the protein content in food than Kjedahl method which often overstates the protein content due to adding the high nitrogen-containing substances.
出处
《当代化工》
CAS
2010年第2期224-226,共3页
Contemporary Chemical Industry
