Characteristics of ultrasound-induced sesamol–soybean peptide composite particles (SSPPs) and SSPP-stabilized Pickering emulsions

Abstract

To improve the properties of soybean peptide-based emulsifiers, non-covalent interactions between sesamol and soybean peptides were induced through ultrasound treatment. Accordingly, sesamol–soybean peptide composite particles (SSPPs) with excellent interfacial properties and antioxidant capacity were prepared to achieve the long-term stabilization of emulsion. In SSPPs, the secondary structure of the peptides was altered (increased β-sheet content) and the surface hydrophobicity was reduced owing to hydrophobic interactions and hydrogen bonding between sesamol and soybean peptides. Moreover, the SSPPs could effectively encapsulate sesamol. With the increase in sesamol concentration, the particle size of SSPPs gradually reduced, while their solubility and antioxidant activity increased. LC-MS/MS revealed that the addition of sesamol led to the generation of small peptides (length: 3–7 amino acids) in SSPPs. The proportion of hydrophobic amino acids at the N- and C-terminals of these peptides was >60 %, and the C-terminus was enriched with basic amino acids, which conferred strong antioxidant capacity to the SSPPs. The SSPPs could be effectively adsorbed and rearranged at the oil–water interface, forming an obvious interfacial barrier. Ultimately, Pickering emulsions stabilized by SSPP-1.5 showed the strongest resistance to droplet aggregation as well as lipid and protein oxidation during 30 days of storage.