Ethanol modulation of egg white microgels assisted by ultrasound-microwave treatment: mechanisms for size control and...

This study establishes a novel strategy for preparing egg white microgels (EWM) with adjustable particle size via ultrasound-microwave (US-MW) treatment assisted by low-concentration ethanol. The addition of ethanol effectively decreased the particle size of microgels, and the sample prepared with 10% ethanol (EWM-E10) reached a minimum size of 109.7 ± 3.0 nm while maintaining high system stability. This combined approach promoted structural unfolding of the proteins, which increased surface negative charge and electrostatic repulsion, thereby enhancing the stability of the system. Atomic force microscopy (AFM) indicated that EWM-E10 exhibited the highest specific surface area (2.04 ± 0.02 m²/g), moderate roughness (0.64 ± 0.03 nm), and good interfacial deformability. In addition, hydrogen bonding and hydrophobic interactions were the main intermolecular forces that sustained microgels. These findings elucidate the mechanistic role of ethanol as a facilitator in US-MW mediated structural reorganization, providing deeper insights for the rational design of functional protein-based colloids.