Interfacial regulation of high internal phase emulsions using steviol glycosides

High internal phase emulsions (HIPEs) feature a high internal phase volume fraction (φ ≥ 74%) and are widely used in the food industry. The aim of this study was to investigate the interfacial behavior of the ternary conjugated complex (WSE) formed by whey protein isolate, sodium alginate, and steviol glycosides (STE), and to elucidate its mechanism as an emulsifier for preparing and stabilizing HIPEs. The study focused on the effects of STE content on the dynamic adsorption of the complex at the oil-water interface, its rheological properties, and the macroscopic stability of the resulting emulsion.

Steviol glycoside concentration regulates HIPE performance through distinct interfacial mechanisms. At 1 g kg^-1, protein-polysaccharide interactions dictated the interfacial properties; at approximately 3-10 g kg^-1, synergistic co-adsorption enhanced interfacial viscoelasticity significantly; at 20 g kg^-1, intense competitive adsorption lowered interfacial protein adsorption considerably. Consequently, WSE complexes with approximately 3-6 g kg^-1 STE yielded optimal HIPEs, exhibiting robust centrifugal stability and resistance to phase separation for 30 days at 4 °C. These emulsions also preserved their shear recovery properties following freeze-thaw cycles.

Precise control of STE content enables targeted optimization of the interfacial properties of ternary complexes, producing stable HIPEs with gel-like structures. This study provides a theoretical foundation for the preparation of food-grade HIPEs, investigating the mechanism through which the competitive and synergistic adsorption of components in protein-polysaccharide-surfactant complexes affect interfacial stability. © 2026 Society of Chemical Industry.