Fabrication of soy protein-polyphenol covalent complex nanoparticles with improved wettability to stabilize high-oil-phase curcumin emulsions.

Background: Recent studies have shown that the wettability of protein-based emulsifiers is critical for emulsion stability. However, few studies have been conducted to investigate the effects of varying epigallocatechin gallate (EGCG) concentrations on the wettability of protein-based emulsifiers. Additionally, limited studies have examined the effectiveness of soy protein-EGCG covalent complex nanoparticles with improved wettability as emulsifiers for stabilizing high-oil-phase (≥ 30%) curcumin emulsions.
Results: Soy protein isolate (SPI)-EGCG complex nanoparticles (SPIE _n ) with improved wettability were fabricated to stabilize high-oil-phase curcumin emulsions. The results showed that EGCG forms covalent bonds with SPI, which changes its secondary structure, enhances its surface charge, and improves its wettability. Moreover, SPIE _n with 2.0 g L ^-1 EGCG (SPIE _n-2.0 ) exhibited a better three-phase contact angle (56.8 ± 0.3 ^o ) and zeta potential (-27 mV) than SPI. SPIE _n-2.0 also facilitated the development of curcumin emulsion gels at an oil volume fraction of 0.5. Specifically, the enhanced network between droplets as a result of the packing effects and SPIE _n-2.0 with inherent antioxidant function was more effective at inhibiting curcumin degradation during long-term storage and ultraviolet light exposure.
Conclusion: The results of the present study indicate that SPIE _n with 2.0 g L ^-1 EGCG (SPIE _n-2.0 ) comprises the optimum conditions for fabricating emulsifiers with improved wettability. Additionally, SPIE _n-0.2 can improve the physicochemical stability of high-oil-phase curcumin emulsions, suggesting a novel strategy to design and fabricate high-oil-phase emulsion for encapsulating bioactive compounds. © 2024 Society of Chemical Industry.
(© 2024 Society of Chemical Industry.)