Abstract: Whey protein isolate (WPI) emulsion gels were prepared through glucono-δ-lactone-induced gelation and were incorporated with both hydrophilic and hydrophobic functional ingredients (sodium isoascorbate and vitamin E). The study focused on the relationship between the microstructure of emulsion gels and the stability of vitamins incorporated in them. The denaturation level of WPI under thermal treatment (85 ℃) was controlled to modulate the microstructure of emulsion gels and the stability of the incorporated vitamins. The findings indicated that the droplet size of emulsions was increased, and the zeta-potential was reduced with the increase in heat treatment time, while the apparent viscosity was not significantly affected. Textural and rheological analyses showed that the hardness and storage modulus of emulsion gels were enhanced with the increase in heat treatment time, but the elasticity was weakened. The prolongation of heat treatment time was beneficial to improve the stability of different vitamins during storage at different temperatures, and there was a synergic effect between the mixed vitamins. It was concluded that the microstructure of emulsion gels could be adjusted by thermal treatment to control the stability of different vitamins incorporated.

Key words: emulsion gel, thermal treatment, microstructure, vitamins, stability