毛细管电泳法对乳及乳制品中真蛋白的测定

Use of Capillary Electrophoresis for Determination of Genuine Proteins in Milk and Milk Products

利用毛细管电泳法对市售乳清蛋白粉、采自当地奶牛场的牛初乳及原料奶、同一品牌不同阶段或同一阶段内不同厂家、不同国别的婴儿配方奶粉、不同保质期的液态奶、不同国别的超高温灭菌(UHT)奶和酸奶、国产复原乳中α-乳白蛋白(α-Lac)、β-乳球蛋白A(β-LgA)及β-乳球蛋白B(β-LgB)的质量分数进行测定。结果表明:α-Lac、β-LgA及β-LgB的质量分数在乳清蛋白粉、牛初乳及原料奶中依次降低。液态奶中上述3种蛋白的质量分数与保质期有关,一般保质期越久的产品,上述3种蛋白的质量分数越低。大多数酸奶中α-Lac的质量分数均高于UHT奶。婴儿配方奶粉中α-Lac质量分数随着阶段数的增加而增加,而且同一阶段内不同厂家不同国别配方奶粉中α-Lac质量分数差异也较大,并非进口奶粉中α-Lac质量分数均比国产奶粉高。

The contents of theα -lactalbumin （α-Lac）, β -lactoglobulin A （β-LgA） and β -lactoglobulin B （β-LgB） were determined by capillary electrophoresis in whey protein powder, bovine colostrum and raw milk from the local farm, infant formula of the same brand but for different age stages or of the same age stages from different plants and countries, liquid milk with different shelf-life, ultra-high temperature （UHT） milk and yogurt from different countries and domestic reconstituted milk. The contents of the above three proteins decreased in the order of whey protein powder, bovine colostrum and raw milk, and were negatively related to the shelf-life of milk and milk products. The content of α-Lac in most of the yogurts were higher than that in UHT milk. The contents of the α -Lac in infant formula increased with the age stage. Infant formula with the same age stages of different brands and countries had significant differences in the contents of α-Lac. The contents of α-Lac in imported formula were not always higher than those from domestic ones. The results provide a valuable asset for the analysis of true proteins in milk and milk products.