(54j) Foam Film Drainage and Emulsification of Milk Proteins and Alternatives

Proteins in food, cosmetic and pharmaceutical foams influence the interfacial and bulk properties of formulations. Formation of bubbles and drops accompanying foam formation and emulsification involves interfacially-dominated pinching of fluid necks and dynamic adsorption at freshly-formed interfaces. Lifetime and stability of foams and emulsions can be enhanced by changing the drainage kinetics in liquid films that separate gas pockets in foam, and droplets in emulsions. In this contribution, we present several examples of our studies of pinching dynamics as well as drainage kinetics relevant to stability, formation and lifetime of foams and emulsions. An interplay of capillarity, inertia and viscous stresses drives flows within pinching necks and draining films of simple, Newtonian fluids. By careful examination of interfacial and nonlinear flows in bespoke but frugal set-ups for draining films and pinching necks, we characterize the additional influence of proteins, or their complexes formed with polysaccharides and lipids often added to food formulations.