Ultrasonic enhancement of structural and emulsifying properties of heat-treated soy protein isolate nanoparticles to fabricate flaxseed-derived diglyceride-based pickering emulsions

Flaxseed-derived diglyceride (DAG)-based Pickering emulsions were fabricated using soy protein isolate (SPI) nanoparticles as stabilizer. The SPI nanoparticles were prepared under the combined action of heating and ultrasound treatment. The SPI nanoparticles exposed to 600 W power exhibited the smallest particle size (133.36 nm) and zeta potential (-34.77 mV). Ultrasonic treatment did not significantly impact the polypeptide chain's primary structure but induced changes in the secondary structure. The Pickering emulsions stabilized with ultrasound-treated SPI nanoparticles showed smaller particle size, lower zeta potential, and improved emulsifying properties. Notably, at 450 W power, these emulsions showed a higher solid–liquid balance, reduced mean square displacement, backscattering fluctuations, and turbiscan stability index. Besides, they displayed a more compact microstructure with smaller droplets. In conclusion, SPI subjected to heating and 450 W ultrasound power resulted in the fabrication of DAG-based Pickering emulsions with enhanced microstructure and stability.