Phase separation and spreading dynamics of French vinaigrette

Abstract

Phase separation can be observed when vinaigrette is poured on a kitchen plate under certain conditions. The phase separation in vinaigrette, which comprises olive oil, vinegar, and mustard for stabilization and taste, is characterized by the outward spreading of olive oil from the main film. This phase separation and the phenomena that trigger it were investigated in this study. Moreover, the spreading dynamics of the vinaigrette were examined by analyzing the spreading factor and its rate. The spreading of different formulations of the vinaigrette was probed in this regard by varying the mass concentration of vinegar from 10% to 40% and the amount of mustard from 0.1 to 0.5 g. The emulsion films were placed on a white tile substrate with similar characteristics to those of a kitchen plate at 21 °C and a relative humidity of 50%. The spreading dynamics followed two distinct regimes; increasing the vinegar concentration of mustard-free formulations led to decreases in the spreading factor of the first regime and the spreading rate. The addition of mustard had a similar effect on the spreading factor of the first regime. The variations in these two parameters were related to changes in the system viscosity. The latter was found to be a function of the mustard and vinegar concentrations. Phase separation occurred at vinegar concentrations below 30% because of a competition between the spreading and the existing instabilities in the vinaigrette. This phenomenon did not affect spreading dynamics.