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

The effect of thermal pretreatment ( 90 ℃, 5 min) 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 ( 0¹4 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.