Interfacial and foaming properties of five commercial dairy products and two types of proteose-peptone fractions

Functional properties of surfactants contained in dairy products, like emulsifying, foaming and wetting properties, result from their capacity to reduce the surface tension by adsorption and formation of cohesive films at the interface. A wide variety of techniques have been developed to determine surface tension, but those that give dynamic measurements, rather than equilibrium measurements of surface tension, are more suitable to study functional properties. Furthermore, the surface activity of
surfactants depends on the mechanical properties of the films that are formed at the interface, which are strongly influenced by the intramolecular interactions established.
The aim of this study was to investigate the kinetics of adsorption, mechanical properties of monolayer films and foaming properties of five different commercial dairy products (whey protein concentrate (WPC), buttermilk, butter serum and two skimmed milks) and two proteose-peptone fractions.