乳清分离蛋白-葡聚糖接枝物Pickering乳液的稳定性研究

为提高蛋白基Pickering乳液稳定性，采用美拉德反应制备乳清分离蛋白(WPI)-葡聚糖(Dex)接枝物，然后利用该接枝物制得蛋白基固体颗粒，再与中链甘油三酯制备Pickering乳液，考察WPI-Dex接枝物对蛋白基固体颗粒乳化活性、乳化稳定性和蛋白基Pickering乳液乳析指数的影响，以及Pickering乳液在不同pH、加热温度、贮藏时间下粒径的变化。结果表明：扫描电镜观察到共价接枝Dex将WPI形貌结构由球状转变为片状，十二烷基硫酸钠-聚丙烯酰胺凝胶电泳证实干法美拉德反应成功制备了WPI-Dex接枝物；与WPI相比，WPI-Dex接枝物的乳化活性和乳化稳定性分别增加了57.8%和138.5%;WPI和WPI-Dex接枝物Pickering乳液贮藏30 d时的乳析指数分别为52.3%和36.0%,WPI-Dex接枝物使Pickering乳液的乳析稳定性提高了31.2%;WPI-Dex接枝物Pickering乳液具有良好的pH稳定性、热稳定性和贮藏稳定性。综上，蛋白质糖基化接枝修饰是提高天然蛋白质Pickering乳液稳定性的有效方法。

Stability of whey protein isolate-dextran conjugate Pickering emulsion

In order to improve the stability of protein-based Pickering emulsion, Maillard reaction was used to prepare the whey protein isolate(WPI)-dextran(Dex) conjugate. The WPI-Dex conjugate was used to prepare protein-based solid particles, and then Pickering emulsion was prepared with medium-chain triglyceride. The effects of the WPI-Dex conjugate on the emulsification activity, emulsion stability of protein-base solid particles and creaming index of Pickering emulsion were investigated, as well as the change of diameter of Pickering emulsion under different pH, heating temperature and storage time. The results showed that scanning electron microscopy (SEM) observed the covalently grafted Dex transformed the morphologic structure of WPI from globular to flake. The WPI-Dex conjugate was successfully prepared by the dry state Maillard reaction, which was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Compared with WPI, the emulsification activity and emulsion stability of WPI-Dex conjugate increased by 57.8% and 138.5%, respectively. The creaming indexes of WPI and WPI-Dex conjugate Pickering emulsion stored for 30 d were 52.3% and 36.0%, respectively, and the creaming stability of WPI-Dex conjugate Pickering emulsion increased by 31.2%. WPI-Dex conjugate Pickering emulsion had good pH stability, thermal stability and storage stability. In conclusion, the glycosylation graft modification of protein is an effective method to improve the stability of natural protein Pickering emulsions.