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

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. (C) 2007 Elsevier Ltd. All rights reserved.