Stability of egg white-stabilized edible oil emulsions using conductivity technique

Stability of egg white-stabilized oil emulsions is investigated using the conductivity technique. The edible oils investigated were corn, olive, soybean and sunflower. Several oil volume fractions (0.25–0.50 v/v), and several egg white concentrations (0.05–0.50 mg/ml) were studied. The observed conductivity vs time curves were characterized by a short period (lag time) where the conductivity of an emulsion remained essentially equal to that during the homogenization period, followed by an increase in conductivity values that exhibit a non-linear concave up slope followed by a somewhat steady-state, plateau value. This pattern of conductivity was fit to the sigmoid function, which revealed the model parameters that were used to quantify a new emulsion stability (ES) index in units of time. ES was conceptually related to pertinent variables appearing in the sigmoid function. Except with olive oil emulsions, one may say that at a given egg white concentration, ES increases with increasing oil volume fraction (OVF), and at a given OVF, ES increases with increasing egg white concentration. Finally, emulsifier activity was found to increase with increasing OVF.