Linear viscoelastic properties of sucrose ester-stabilized oil-in-water emulsions

This paper deals with the influence of composition [sucrose ester SE and oil O concentrations] and temperature on the linear viscoelasticity properties of highly concentrated oil-in-water emulsions, using a hydrophilic sucrose palmitate as emulsifier. Different oil-in-water emulsions were prepared using a sucrose palmitate (SE = 1-5 wt %) with a hydrophilic-lipophilic balance of 15, sunflower oil (O = 60-80 wt %) and water. Oscillatory measurements were carried out in the linear viscoelasticity region. The relaxation time spectra of the emulsions were calculated using regularization techniques and were fitted to an empirical model proposed by Madiedo (1996). The results obtained are explained on the basis of the relationship among linear viscoelasticity properties, droplet size distribution, and characteristics of the continuous phase. Thus, an increase in sucrose palmitate concentration produces higher values of the linear viscoelasticity functions and a broader plateau region in the relaxation time spectrum, which suggests a certain enhancement of the elastic network. (C) 1998 The Society of Rheology. [S0148-6055(98)01206-1].