Exploring alternative and novel animal-based protein emulsifiers for Pickering emulsions: Structural and functional insights

Protein-based particles (PPs) are emerging as versatile, biocompatible, and biodegradable emulsifiers in the food industry, particularly for Pickering emulsions (PEs). These protein particles act as colloidal stabilizers for both hydrophobic and hydrophilic bioactive compounds (bioactives) due to their irreversible adsorption at the oil-water interface and formation of a steric barrier. This review focuses on the mechanisms of emulsion stabilization, production, properties, and applications of protein-based PEs, regardless of their animal or plant origin. The influence of particle concentration, co-molecules, pH, and salt on stability is discussed. Casein forms heat-resistant highly hydrated micelles; whey protein isolate (WPI) can be modified for improved particle size and functionality; egg proteins stabilize high internal phase emulsions (HIPPEs) via gel-like structures; gelatin offers ligand binding and cross-linking; silk and myofibril polypeptides enhance mechanical, thermal, and 3D printing properties. The role of steric hindrance, wettability, and interfacial adsorption efficiency is emphasized as the primary determinant of PE stability. Additives such as polyphenols and polysaccharides further enhance stability and expand food applications.