Interaction among protein, daidzein and surfactants in the WPI-based daidzein self-microemulsifying delivery system

The self-microemulsifying delivery system was fabricated by whey protein isolate (WPI), daidzein (Dai) and surfactants, the interaction of WPI, Dai and D-α-Tocopherol polyethylene glycol succinate (TPGS) was hereby studied in the absence or presence of Tween 20. The increase of surfactant concentration led to the decrease of the modulus and changes of protein interfacial conformation, which allowed the formation of a strong intermolecular network. The environment and structure of WPI and daidzein could be changed by TPGS, and the addition of Tween 20 could further enhance the interaction between the components by changing TPGS structure. With the increase of surfactants and oil phase, Ksv and Ka values of WPI-Dai increased first and then decreased. Therefore, the interaction between the components was also dependent on the WPI-surfactant ration. These findings provide a potential strategy for designing microemulsion food system based on the understanding of the interactions among individual composition of microemulsions.