High-intensity ultrasound together with heat treatment improves the oil-in-water emulsion stability of egg white protein peptides

Abstract In this article, high-intensity ultrasound (800 W, 20 kHz, 30% amplitude, 15 min) together with heat treatment (90 °C, 30 min) was employed to improve the interfacial properties of egg white peptides and to enhance the stability of prepared emulsions. The high-intensity ultrasound treatment caused peptides to depolymerize, producing a smaller particle size (60.52 nm), increasing the surface charges, and exposing the hydrophobic groups. The interfacial activity of peptides was increased after ultrasound and heat treatment, with a decrease in interfacial tension and an increase in contact angle (from 44.8° to 68.7°). The treated peptides exhibited remarkably enhanced antioxidant activity. Secondary structure analysis demonstrated that ultrasound and heat treatment significantly reduced β-sheets and increased the random structure content remarkably. Emulsions prepared from the ultrasonicated and heat-treated peptides exhibited better dispersion and lower viscosity, together with higher interfacial protein contents and higher proportions of interfacial adsorbed proteins. The ultrasonicated and heat-treated peptide-stabilized emulsions exhibited better ionic, thermal, and storage stabilities, and reduced lipid oxidation. Thus, the findings indicate that this method provides a feasible and efficient approach to broaden the application of small molecule peptides for the stabilization of emulsions.