Emulsion Drops with Complex Interfaces: Globular Versus Flexible Proteins

Abstract This study focuses on the flow behavior of emulsion drops with complex interfaces. The experimental approach includes three different length scales: (i) interfacial rheology is discussed for adsorbed proteins with different molecular structure (compact and globular for beta‐lactoglobulin versus flexible and random coil for beta‐casein); (ii) the flow of single drops with macromolecular adsorption layers is studied using optical flow cells; (iii) dilute emulsions are investigated using rheology and rheo‐small angle light scattering (rheo‐SALS). Different hydrodynamic models for drops with and without interfacial viscoelasticity are assessed. For the case of rigid interfacial layers, a comparison with capsule suspension models suggests that drops stabilized by adsorbed particles or globular proteins behave like “soft capsules” surrounded by a jammed shell. Their behavior on the single drop level is similar to the mechanics of red blood cells or vesicles. magnified image