预热处理对乳清分离蛋白水包油乳状液特性和物理稳定性的影响

Influence of heat pretreatment on the characteristics and physical stability of whey protein isolate-stabilized rapeseed oil-in-water emulsions

本实验主要研究了加热预处理(90℃,5 min)对乳清分离蛋白作为稳定剂所制备的菜籽油水包油型乳状液的特性和物理稳定性的影响。测定了乳状液在储藏期间的ζ-电势、粒径、絮凝指数、分层指数、流变特性和乳状液中蛋白质分配系数的变化趋势。研究结果表明,与天然乳清分离蛋白相比,经过预热处理的乳清分离蛋白能够显著降低乳状液在整个储藏期间(0~14 d)的物理稳定性(p<0.05),具体表现为较低的ζ-电势(p<0.05),以及较高的粒径、絮凝指数、分层指数和粘度(p<0.05)。与此同时,加热处理导致的乳清分离蛋白变性和聚集,能够显著增加其在乳状液界面蛋白膜表面的分布(p<0.05),从而验证了上述乳状液物理稳定性的结果。上述结果表明,加热预处理显著降低了整个乳状液在储藏期间的物理稳定性,为乳清分离蛋白在乳状液中的合理应用奠定了理论基础。

The effect of thermal pretreatment（90 ℃ ,5 rain） on the properties and physical stability of rapeseed oil-in-water emulsion of prepared by using whey protein isolate as stabilizer were investigated. The changes trend of ζ- potential, particle size,flocculation index, creaming index, rheological property and the partition coefficient of protein in the emulsion during storage were measured.The results showed that the heat pretreatment whey protein isolate could significantly reduce the physical stability of the emulsion during storage（0-14 days）compared with the natural whey protein isolate （p 〈 0.05 ）, and the specific performance of lower ζ-potential （p 〈 0.05 ）, and higher particle size, flocculation index, creaming index and viscosity （p 〈 0.05）. At the same time, the denaturation and aggregation of whey protein isolate caused by preheating treatment could significantly increase the distribution of the protein on the surface of the emulsion membrane （p 〈 0.05 ） , thus confirming the physical stability of the emulsions.The results indicated that the thermal pretreatment significantly reduced the physical stability of the whole emulsion during storage and laid a theoretical foundation for the rational application of whey protein isolate in the emulsion.