Linear Viscoelasticity of Salad Dressing Emulsions

Abstract

The effects of oil, emulsifier, and starch concentrations on the linear viscoelasticity of oil/water salad dressing emulsions were studied. Oil concentration ranged between 35 and 55 wt %. Emulsions were prepared using a mixture of egg yolk (0−6 wt %) and a highly hydrophilic sucrose ester (0−10 wt %) as emulsifier. Starch (0−2 wt %) was included in the formulation to study the influence of increasing continuous phase viscosity. The influence of the concentration of these components on the linear viscoelasticity functions was generalized by using the plateau modulus as a normalization factor. An increase in oil concentration did not qualitatively modify the linear viscoelastic behavior. A frequency displacement of the plateau region took place when egg yolk and sucrose ester concentrations were changed. Results were analyzed by calculating the relaxation time spectra of these emulsions. The BSW-CW model was used to fit these spectra. The pseudo-terminal relaxation time increases with egg yolk concentratio...