乳蛋白对豆乳凝胶物性学特征的影响机理

Effect and Underlying Mechanism of Milk Protein on the Physical Characteristics of Soymilk Gel

为改善豆乳酸奶制品,分别从体系层面、颗粒层面和分子层面研究不同类型的乳蛋白——乳清分离蛋白(whey protein isolate,WPI)、乳浓缩蛋白(milk protein concentrate,MPC)和酪蛋白酸钠(sodium caseinate,NaCas)对豆乳凝胶特性的影响及机理。结果表明:WPI(≥20%)、40%NaCas的加入可以有效增强豆乳凝胶强度,其中WPI(≥20%)的作用最为显著。低替代比例的乳蛋白可以显著减小凝胶颗粒的粒径,而高比例的WPI会大幅度增大体系的凝胶颗粒。在微观结构方面,MPC的添加使得凝胶结构更为致密规则,NaCas的添加形成了细丝网状结构,而WPI的添加使得凝胶结构趋于不规则、致密。聚丙烯酰胺凝胶电泳及其光密度扫描结果显示,添加WPI(≤20%)可能会促进大豆7S蛋白的β亚基参与凝胶,而NaCas则会阻碍大豆11S蛋白碱性亚基的凝胶化。

In order to improve soy yogurt products,the effect and underlying mechanism of different types of milk proteins,whey protein isolate(WPI),milk protein concentrate(MPC),and sodium caseinate(NaCas),on the gelation behavior of soymilk were investigated.The results showed that the incorporation of WPI(≥20%)or 40%NaCas could effectively enhance the strength of soymilk gels,and WPI(≥20%)had the most positive effect.Low levels of replacement of milk proteins could significantly decrease the particle size of soymilk gels,while high proportions of WPI replacement had the opposite effect.In term of microstructure,MPC led to more organized and denser networks.NaCas induced the formation of filamentous networks.WPI induced the formation of a less organized but denser gel structure.Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)showed that WPI(≤20%)might promote the involvement of theβsubunit of soybean 7S protein in gel formation,while NaCas might hinder the gelation of the basic subunit of soybean 11S protein.