Use of a Flow Cell Apparatus to Determine the Emulsifying Properties of Casein

A newly designed flow cell apparatus was used to investigate the effect of protein concentration and oil fraction on casein stabilized emulsions. Emulsifying capacity showed an exponential decrease with increasing casein concentration. The microstructure of the emulsion suggested that insufficient surface coverage and mechanical stress on oil droplets' membranes were factors responsible for its collapse. Protein load and membrane thickness calculations, showed that the minimal surface coverage, or the minimal membrane thickness required to prevent emulsion collapse, increased with the oil fraction. This last relationship is suggested as a membrane resistance indicator for film forming proteins.