The Effect of Egg White Albumin on the Rheological and Physiochemical Properties of Sunflower Oil Emulsion

In emulsion-based food systems, the desired physical and rheological properties are essential for the storage and transportation of the products. Proteins with special emulsifier properties play a special role in the production of such products. In this study, egg white albumin at different concentrations (0.1 to 5% w/w) was used for the manufacture of oil in water emulsions and the effect of this protein on the physical and rheological behaviour of the manufactured emulsions was studied. The results showed that creaming behaviour of the emulsions did not occur at the concentrations of 3 and 5% of albumin during 21 days of storage at ambient temperature. The particle size was larger in the case of the emulsion containing the lowest amount of albumin (0.1%) compared to the other samples (p<0.05). Zeta potential of the emulsion samples was in the range of -21 to -36 mV, representing the high physical stability of these systems. However, this parameter (zeta potential) was significantly lower in the case of the emulsion containing 5% albumin (p<0.05). The results from the rheological analysis indicated that Carreau was the best model for describing flow behavior data. Zero shear viscosity was lower in the samples containing a lower amount of albumin (i.e., 0.1-1%). The shear-thinning behavior increased with increasing albumin concentration. The frequency sweep test demonstrated that storage modulus was higher than viscous modulus in all of the frequency ranges applied. The morphological investigations indicated a more homogeneous structure in the samples containing higher amounts of egg albumin. Overall, the findings of this study demonstrated that the presence of egg white albumin in the basic emulsion systems can improve their physical stability and the rheological properties.