国内外乳品真蛋白检测方法的进展

Progress on Determination Methods of True Protein in Milk and Dairy Products

介绍了乳品真蛋白的定义,比较了国内外牛乳蛋白质检测的标准方法,简述了乳品真蛋白的快速检测方法,提出了我国国家标准需要改进的方向,即在样品处理前先用150g/L的三氯乙酸溶液使乳中的蛋白质沉淀,用滤纸分离,再用凯氏定氮法分别测定沉淀和滤液中的蛋白态氮含量和非蛋白态氮含量,计算蛋白质含量。如果改用pH4.6来沉淀酪蛋白,同样的方法还可以用于测定乳品中酪蛋白。

Definition of true protein in milk was introduced; the standardized methods of protein determination were compared domestically and abroad; fast determination methods were also described. Our National standard methods of protein determination need to be improved. The suggestions were： Samples should be pre-treated with 15% （w/ v） trichloroacetic acid solution and precipitate protein was separated by filtration. Nitrogen contents of protein precipitate and the triehloroacetie acid solution were determined by Kjeldahl methods. The same principal and method could be used for determination of casein in dairy products by isoeleetrie precipitation at pH 4.6.