Sesame protein-β-glucan conjugates for the stabilization of peony seed oil emulsions: Characterization, rheology, and oxidative stability analysis

ABSTRACT Peony seed oil (PSO), rich in unsaturated fatty acids and bioactive compounds, is highly susceptible to oxidative degradation, which limits its storage stability and application. In this study, sesame protein (SP) was modified via Maillard reaction with β-glucan (β-glu) to form SP-β-glu conjugates, aimed at improving the stability of PSO emulsions. The optimal preparation conditions were a protein-to-polysaccharide dry-mass ratio of 2:1, a reaction temperature of 65 °C, and a reaction time of 122 min. The conjugates significantly enhanced the solubility, emulsifying activity, and antioxidant properties of SP. At a protein concentration of 1.5g/L and an and oil phase volume fraction of above 500 mL/L or higher, stable emulsions were formed with potential for high internal phase applications. Compared to SP-stabilized emulsions, those prepared with SP-β-glu conjugates showed smaller droplet size, higher absolute zeta potential, lower turbidity, and greater interfacial protein adsorption. Rheological measurements revealed improved elasticity and interfacial film strength. Additionally, SP-β-glu emulsions exhibited excellent thermal, pH, and ionic stability, and effectively delayed the oxidation of linoleic and α-linolenic acids. In vitro digestion confirmed superior structural and electrostatic stability under gastric conditions. These findings offer a promising strategy for enhancing the functional properties of underutilized sesame protein and developing stable protein-polysaccharide emulsions for functional food applications.