Surface Load and Interfacial Composition of Protein-Stabilized O/W Emulsions

Oil-in-water (O/W) emulsions, i.e., the dispersion of oil droplets in a continuous water phase, are widely present in foods. In such systems, oil droplets are often physically stabilized by proteins—amphiphilic biopolymers that can act as emulsifiers. Despite the fact that the interface is very thin (typically 1–15 nm for protein-stabilized interfaces), it controls to a large extent the physical stability of the droplets. Therefore, characterizing the adsorption behavior of proteins is of high importance. Measurements of the surface load (i.e., mass of emulsifier adsorbed per unit of oil–water interfacial area) and interface composition are useful in that respect. This chapter provides a protocol and guidelines for the determination of the surface load and interfacial composition of fluid O/W emulsions. Although centered on protein-stabilized emulsions, the procedure described may be easily adapted to emulsions prepared with other water-soluble emulsifiers.