Linear and non-linear viscoelasticity of emulsions containing carob protein as emulsifier

Abstract

The effect of protein concentration (0.125–1 wt%) on linear viscoelastic properties and microstructure of O/W emulsions stabilized by carob protein was studied. Similar results were obtained in previous studies with gluten and soya proteins. All the emulsions showed a significant linear viscoelastic range, which increased with protein concentration. Linear and non-linear viscoelastic properties of concentrated O/W emulsions containing sunflower oil (75 wt% O), water and a vegetable protein (carob, gluten or soya, 1 wt%) were also compared. Carob protein based emulsions showed higher linear and non-linear viscoelastic properties (i.e. dynamic viscoelastic functions, relaxation modulus, and flow properties) than emulsions with soya or gluten. Non-linear viscoelasticity modeling was performed by using the Wagner model that assume time-strain separability. The memory function and damping function were reproduced by the generalized Maxwell model and the Soskey–Winter equation. The ability of the Wagner model to predict flow properties was confirmed for the three emulsions.