pH对脱脂牦牛乳中酪蛋白胶束的影响  

Effect of pH on Casein Micelles in Skim Milk of Yak

作　　者：张光地 何兴芬 杨敏[2,3] 马蓉 杨富民 王海霞[1] ZHANG Guang-di;HE Xing-fen;YANG Min;MA Rong;YANG Fu-min;WANG Hai-xia(College of Food Science and Engineering,Gansu Agricultural University,Lanzhou 730070,China;College of Science,Gansu Agricultural University,Lanzhou 730070,China;Functional Dairy Product Engineering Lab of Gansu Province,Lanzhou 730070,China)

机构地区：[1]甘肃农业大学食品科学与工程学院,甘肃兰州730070 [2]甘肃农业大学理学院,甘肃兰州730070 [3]甘肃省功能乳品实验室,甘肃兰州730070

出　　处：《现代食品科技》2018年第9期158-164,197,共8页Modern Food Science and Technology

摘　　要：通过对不同pH下牦牛乳酪蛋白胶束中主要矿物质含量变化、单体含量变化以及荧光光谱和粒径变化的测定，分析pH对脱脂牦牛乳中酪蛋白胶柬的影响。结果表明：随着酸化程度的增加，酪蛋白胶束发生聚集，上清液中酪蛋白单体的含量降低，在pH≤4．6时，聚集的酪蛋白胶束发生溶解，单体含量又出现增加；Ca和P的含量先降低后增加，在pH 7时出现最低值，此时酪蛋白胶束结构稳定，pH〈7．0时胶束磷酸钙发生溶解，pH〉7．0随着静电作用的持续增大酪蛋白胶柬结构更加松弛直至解离，Mg不参与酪蛋白胶束结构的形成，Na含量的变化主要由碱化操作加入的NaOH引起；粒径在pH〈5．8时出现明显增加，酪蛋白胶束发生聚集，在pH 7时同样出现最低值，pH〉7．0时酪蛋白胶隶逐渐变得松弛，粒径增大，但在pH〉7．8时，粒径减小，酪蛋白胶束发生解离；荧光光谱的变化也同样能反映出酪蛋白胶束的这些变化。The effect of pH on casein micelles in skim milk of yak was evaluated by soluble mineral, casein molecule content, fluorescence properties and particle size at pH 4.6-8.2. The results showed that the aggregation of casein micelles was increased and the content of casein monomer in the supematant was decreased with the degree of acidification. At pH≤4.6, the agminated casein micelles was dissolved and the content of casein monomer increased. The content of Ca and P first decreased and then increased, and reached the smallest value at pH 7, casein micelle structure was stable at this time. At pH〈7.0, colloidal calcium phosphate disassociated from yak casein micelles; with the continuous increase of electrostatic effect, the structure of casein micelle became more relaxed until dissociation at pH〉7.0. Mg were not involved in the formation of casein miceUar. The casein miceUe was clustered obviously at pH〈5.8, and the particle size was increased significantly, and also reached the smallest value at pH 7. The casein micelle became relaxed gradually at pH〉7.0 and particle size increased, but casein micelles dissociated at pH〉7.8, and particle size decreased. The changes in fluorescence spectra also reflected these changes of the casein micelles.

关 键 词：牦牛乳 酪蛋白胶束 矿物质 荧光光谱 粒径 

分 类 号：TS252.42[轻工技术与工程—农产品加工及贮藏工程]