Optimization and characterization of high internal phase double emulsion (HIPDE) stabilized by with soybean protein...

This study aims to formulate a stable high internal phase double emulsion (HIPDE) using soybean protein isolate (SPI), gallic acid (GA), and xanthan gum (XG). To prepare HIPDE, W₁/O was formulated with the water phase dispersed in the oil phase using polyglycerol polyricinoleate (PGPR) as a stabilizer. Thereafter, W₁/O dispersed in W₂ (SPI solution) was used. To stabilize the HIPDE, GA was added in W₁ (0 or 1 %), XG was added in W₂ (0 or 1 %), and the pH of the W phases was adjusted to acidic, neutral, and basic. The samples containing GA in W₁ and XG in W₂ did not phase out during the storage periods and maintained a higher ζ-potential value, a higher apparent viscosity, and a more sustainable droplet compared to others. These results were derived by the interaction between SPI and XG, SPI and GA, or GA and PGPR. Physicochemical crosslinks were formed, such as gallate-derived groups, SPI-GA complexation (Michael addition, Shiff base reaction), and hydrogen bonding. In conclusion, applying the SPI, GA, and XG to HIPDE would contribute to various industries such as food, medicine, and cosmetics.