The relationship between the secondary structure and the emulsifying ability of protein-based particles and the Pickering emulsions stabilized by the zein–lysine complex†

Due to the sustainability and widespread use of proteins, protein-based materials are extensively utilized in the preparation of Pickering emulsions. However, the relationship between the secondary structure of proteins and their emulsifying ability has not been further investigated. This study used the addition of three different amino acids to influence the interaction between zein chains, which may induce changes in the secondary structure of the prepared zein complex particles. This study demonstrates that the emulsifying properties of proteins, such as dispersibility, zeta potential, three-phase contact angles, interfacial affinity, adsorption rates, and the volume of the stabilized oil phase, are closely related to the β-sheet content of the complex particles, providing a theoretical reference for protein-based stabilizers. Additionally, amino acids, as the blocks of proteins, have high compatibility with proteins, and using amino acids as modifiers aligns with the safety requirements for food processing. In this study, the prepared zein–lysine complex particles have good emulsifying ability, capable of stabilizing a 50 (v/v)% emulsion at a lower concentration (10 mg mL⁻¹), and the prepared emulsion exhibits high-temperature stability and ionic resistance. This characteristic makes the emulsion potentially valuable for application in systems with high salt concentrations and those that may undergo heat treatment.