全脂牛乳粉中糖基化酪蛋白分析  

Analysis of glycosylated casein in whole milk powder

作　　者：孙静丽[1] 李林强[1] 朱莉莉[1] 唐露 武媛 

机构地区：[1]陕西师范大学食品工程与营养科学学院,陕西西安710119

出　　处：《食品与机械》2017年第7期6-10,共5页Food and Machinery

基　　金：陕西省农业科技创新与攻关项目(编号:2016NY-212)

摘　　要：研究全脂牛乳粉中糖基化酪蛋白,探讨其酶解特性。重点考察了不同pH、酸及提取方法对酪蛋白提取质量百分数的影响,并通过SDS-PAGE电泳分析酪蛋白,高碘酸—希夫碱染色法及莫氏试验鉴定糖基化酪蛋白,木瓜蛋白酶水解酪蛋白,测定其氨基酸含量。结果表明,pH 4.6时提取酪蛋白的质量百分数显著高于其他组(P<0.05);质量百分数为2%的乙酸(pH 3.58)提取酪蛋白的质量百分数为(40.45±0.66)%,显著高于其他组(P<0.05);鞣酸提取酪蛋白的质量百分数为(46.13±0.46)%,显著高于其他方法(P<0.05);酪蛋白SDS-PAGE电泳结果表明,不同酸、不同方法提取的酪蛋白均有3条带,其分子量均分别为34,24,60ku;高碘酸—希夫碱染色结果表明,分子量为34,24ku的酪蛋白是糖基化酪蛋白;莫氏试验结果表明,乳粉酪蛋白中存在糖基化酪蛋白;酶解结果表明,乳粉酪蛋白经木瓜蛋白酶水解后游离氨基酸含量显著高于鲜乳酪蛋白(P<0.05)。说明全脂牛乳粉中有糖基化酪蛋白,其分子量分别为34,24ku,易于水解。This study investigated glycosylated casein in whole milk powder and explored its enzymatic property.The casein extraction weight percentage were determined by different pH,different acids,and different methods.The casein was analyzed by SDS-PAGE electrophoresis,and the glycosylated casein were identified via the method of periodate-schiff alkali dyeing and the experiment of morse.The casein was hydrolyzed by papain and the amino acid content was determined accordingly.Results：The percentage of casein extracted under pH4.6was significantly higher than that of other groups（P〈0.05）.The weight percentage of casein extracted from acetic acid（pH 3.58）was（40.45±0.66）%,which was significantly higher than that of other groups（P〈0.05）.The percentage（46.13±0.46）% of casein extracted by tannic acid was significantly higher than that of other methods（P〈0.05）.The results of casein SDS-PAGE electrophoresis both showed the same 3bands either different acids or different methods on casein extraction,and their molecular weights were 34,24,and60 ku,respectively,and the 34 and 24ku were glycosylated casein by the method of periodate-schiff alkali dyeing.The results of morse experiment showed that milk powder casein exist glycosylated casein.The content of free amino acid from whole milk powder was significantly higher than that from fresh milk after papain hydrolysis（P〈0.05）.Whole milk powder has glycosylated casein,their molecular weights are 34 and 24ku respectively,which are easy to hydrolysis.

关 键 词：全脂牛乳粉 复原乳 酪蛋白 糖基化 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]