Microgels from egg white as novel stabilizers of Pickering emulsion

Common preparation of microgels is complex. In this study, we aimed to find a convenient method to prepare microgels without high energy input. We prepared egg white microgel (EWM) by ultrasonic-microwave synergistic treatment (US-MW) and evaluate the ability of EWM to stabilize emulsions. The cavitation effect of ultrasound (US) could avoid excessive aggregation of protein caused by microwave (MW) and achieved the regulation of EWM particle size. Compared with EWM prepared by MW and water bath treatment, EWM treated by US-MW had small particle size (233.23 ± 6.49 nm), high absolute value of zeta potential (−25.27 ± 0.74 mV), high hydrophobicity (505.87 ± 5.22) and large contact angle (78.92°), which made it easier to be adsorbed on water-oil interface with higher emulsification, showing great potential in preparation of Pickering emulsions. Emulsions with EWM concentration >1.5% had good stability and EWM showed great ability to stabilize high volume fraction of oil phase (φ = 0.85). Confocal laser scanning microscopy images showed that EWM was adsorbed on the surface of oil droplets, formed physical barrier to stabilize emulsions. Rheological results showed the emulsions (EWM concentration >1.5% and φ > 0.75) had high apparent viscosity and modulus. This study provided a basis for simple preparation of EWM with high emulsifying capacity, and the EWM could effectively stabilize Pickering emulsions which could be further applied in active substance delivery and fat replacement.