Influence of thermal treatment on oil-water interfacial properties and emulsion stabilization prepared by sono-assembled soy peptide nanoparticles

Sono-assembled soy peptide nanoparticles (SPN), originated from large peptide aggregates formed upon enzymatic proteolysis, were successfully fabricated and could act as bifunctional interfacial stabilizer as shown in our previous study. Herein, a continuous work on the potential stabilization mechanism of SPN in response to thermal treatment was carried out, from both the bulk and the interfacial aspect. Results indicated that SPN showed comparable or better surface activity than SPI and could form a stable viscoelastic layer at the oil-water interface. Thermal treatment on SPN considerably accelerated the particle aggregation, which facilitated the adsorption of SPN at the interface with enhanced inter-particle interactions and structural rearrangements, resulting in the formation of interfacial structure with enhanced thickness and stability against coalescence. To further explore how thermal treatment influence SPN at interface, SPN-stabilized emulsion was then subjected to the same thermal treatment. Results obtained showed that enhanced interactions among SPN adsorbed at the interface and so as in the continuous phase was discovered upon thermal treatment, which facilitated the formation of large particle clusters that wrapping the oil droplets. The steric hindrance caused by interfacial aggregation/particle fusion and greater distribution of peptide nanoparticles at the interface endowed the emulsion with extraordinary coalescence stability and enhanced oxidative stability.