乳清分离蛋白聚集体乳化性能及其Pickering乳液稳定性

Emulsifying Properties of Different Kinds of Aggregates from Whey Protein Isolate and Stability of Pickering Emulsions Stabilized with Them

以乳清分离蛋白(whey protein isolate,WPI)为原料,分别在p H 2.0和p H 7.0条件下,85℃加热12 h制备2种不同形态的蛋白质聚集体,研究2种聚集体微观形貌的特征以及不同pH值和盐离子浓度下的乳化性能;采用透射电镜、动态光散射、光学显微镜等技术手段,探究WPI与2种聚集体稳定的Pickering乳液微观结构、盐离子稳定性和热稳定性。结果表明:WPI分别在pH 2.0和pH 7.0且高温加热条件制得2种微观形貌截然不同的蛋白聚集体(纤维状聚集体和球状聚集体),并且2种蛋白聚集体相较于WPI等电点均发生偏移,在不同p H值或盐离子浓度环境下,乳化性能均提高。2种聚集体所稳定的Pickering乳液对不同p H值、盐离子浓度环境下有更好的稳定性,球状聚集体所稳定的Pickering乳液具有更好的热稳定性。这也为WPI聚集体稳定的Pickering乳液在乳饮料中的应用奠定基础。

In this study,whey protein isolate(WPI)was heated at 85℃for 12 h under different pH conditions(pH 2.0 and 7.0)to prepare two different forms of protein aggregates,and the morphological characteristics and emulsifying properties at different pH and salt concentrations of the aggregates were evaluated.The microstructure,salt stability and thermal stability of Pickering emulsions stabilized with WPI and the two aggregates were comparatively investigated by transmission electron microscopy(TEM),dynamic light scattering(DLS)and optical microscopy.The results showed that fibrous and spherical aggregates were obtained at pH 2.0 and 7.0,respectively.The isoelectric points(IP)of the two aggregates shifted away from that of WPI,and the emulsifying activity increased at all pHs and salt concentrations tested compared with WPI.Moreover,the Pickering emulsion stabilized by the aggregates had better stability to severe environments.Notably,the spherical aggregates had better thermal stability.This study provides a basis for the application of Pickering emulsions stabilized WPI aggregates in milk beverages.