脱钙预处理对提高浓缩乳蛋白溶解性的影响

摘要

以脱脂乳为原料,通过超滤、洗滤、离子交换和喷雾干燥制备了脱钙率为0％、11％、19％、27％和37％的浓缩乳蛋白(milk protein concentrate,MPC),并在35℃加速贮藏4个月,采用聚丙烯酰胺凝胶电泳、激光共聚焦、激光粒度仪等方法分析了MPC中可溶性蛋白的含量、组成及其溶解液的微观结构和粒径分布,旨在探讨脱钙程度对MPC溶解性和贮藏稳定性的影响.脱钙MPC的初始溶解度都在95％以上,且随脱钙程度的增加而略有提高.在贮藏过程中,0％脱钙MPC的溶解度显著降低;11％脱钙MPC的溶解度随贮藏时间增加而显著降低;19％ ～37％脱钙MPC的溶解度在贮藏期内几乎不变.MPC溶解度的降低,主要是由酪蛋白聚集所致.MPC的脱钙率越高,其在水中的分散程度越高,且分散程度随贮藏时间降低的速度越慢.综上所述,当脱钙率达到19％及其以上时,MPC具有良好的溶解性和贮藏稳定性.%A series of milk protein concentrate (MPC) with 0％,11％,19％,27％ and 37％ of decalcification were prepared by ultrafiltered-diafiltered-ion exchange-drying methods.Decalcified MPC was stored at 35 ℃ for 4 months.The changes in soluble proteins,microstructure and particle size distribution of reconstituted decalcified MPC were determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis,confocal laser scanning microscopy and static light scattering,respectively.All freshly prepared MPC maintained the solubility above 95％,and only a slightly increased with the increasing in decalcification.During storage,the solubility of MPC without decalcification decreased sharply and the solubility of MPC with 11％ decalcification decreased less,while the solubility of MPC with 19％-37％ decalcification remained almost unchanged.The decrease in solubility of MPC was mainly attributed to the aggregation of caseins.The dispersion of MPC also increased with the increasing decalcification.The result showed the solubility and stability of MPC were well maintained at and above 19％ of decalcification.