碱溶pH对曲拉酪蛋白结构的影响  

Effect of alkaline pH on the structure and properties of casein from kurut

作　　者：张聪[1] 甘伯中[1,2] 文鹏程[1] 郭慧媛[3] 任发政[3] 杨敏[1,2] 张卫兵[1,2] 乔海军[1,2] 

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]甘肃省功能乳品工程实验室,甘肃兰州730070 [3]中国农业大学教育部功能乳品重点实验室,北京100083

出　　处：《甘肃农业大学学报》2013年第1期125-128,134,共5页Journal of Gansu Agricultural University

基　　金：国家自然科学基金资助项目(30960260);“十二五”国家科技支撑计划项目(2012BAD28B07);北京市科技计划项目(D101105046010001);甘肃省自然科学研究基金计划重点项目(1107KJZA227)

摘　　要：以圆二色谱、荧光光谱、浊度、激光粒径等测试手段,研究了经不同pH碱溶处理的牦牛乳曲拉酪蛋白结构的变化.牦牛乳曲拉经pH 6.0～12.0碱溶,等电点沉淀所得酪蛋白湿凝块在pH 7.0磷酸盐缓冲溶液中溶解形成酪蛋白胶束溶液,进行酪蛋白结构测定.结果表明：随碱溶的pH增加,酪蛋白分子的二级结构发生了明显变化,其β-折叠含量先增后降,α-螺旋含量先降后增,疏水性降低,与此同时伴随着酪蛋白粒径的增加、酪蛋白体系浊度降低.碱溶曲拉酪蛋白分子间的疏水作用和静电相互作用在胶束的二次形成过程中起到了重要作用.The association behavior of the casein over alkaline pH range has been firstly investigated by fluorescent technique together with circular dichroism,particle size and turbidity measurements in kurut,naturally fermented yak milk.Yak kurut solutions in the pH range 6.0 to 12.0,isoelectric point deposited casein solution in pH 7.0 phosphate buffer could self-assemble into casein micelles.The results showed that the subunits and secondary structure of casein had a greatly affect dependent on alkaline pH.The helix structure transfer to sheet,then sheet structure transfer to helix led to a decrease in the observed turbidity and hydrophobicity,particle size enlarged of kurut solutions with increasing pH.The hydrophobic interaction and electrostatic action were main interactions in the second formation of kurut solutions casein micelle.

关 键 词：曲拉 酪蛋白 圆二色谱 荧光光谱 粒径 浊度 

分 类 号：S879.1[农业科学—畜牧兽医]