Protein-based emulsion systems: Potential and mechanisms for regulating lipid digestion

Lipid digestion in protein-based emulsions is governed by dynamic interfacial restructuring involving proteins, bile salts, and lipases. This review proposes a qualitative interfacial competition framework to integrate these processes and evaluate candidate rate-limiting processes. Protein interfacial stability (PIS), bile salt displacement capacity (BSDC), and lipase accessibility (LA) are introduced as three interrelated, condition-dependent mechanistic descriptors. Interfacial adsorption, diffusion barriers, physical shielding, and spatial confinement are evaluated as candidate rate-limiting processes whose importance may change during digestion. Lipid structure, interfacial composition, droplet size, and digestive-fluid properties are examined for their effects on interfacial organization, substrate hydrolysis, and product bioaccessibility. A mechanism-oriented methodological framework is also proposed to connect digestion models, interfacial measurements, structural characterization, and product analysis. This framework supports mechanistic comparison across protein-based emulsions and provides a basis for rationally designing foods with controlled lipid digestion.