Ovalbumin-stabilized concentrated emulsion gels

Abstract

In this paper, ovalbumin is used as the sole emulsifier to produce stable concentrated oil (oil phase = 70 wt%) in water emulsion near ovalbumin isoelectric point. The emulsions display excellent stability against flocculation and coalescence at ovalbumin concentration ranging from 0.6 to 1 wt%. The oil–water interfacial tension decreases in the presence of ovalbumin, indicating the adsorption of ovalbumin at the interface. Although the increase in ovalbumin from 0.1 to 1 wt% does not significantly influence the equilibrium interfacial tension, the surface mean diameter of the emulsion droplets decreases as the concentration increases from 0.1 to 1 wt%. These emulsions exhibit solid gel-like behaviour. At low ovalbumin concentrations (0.1–0.4 wt%), emulsions undergo a phase separation after 24 h. We hypothesize that emulsions with higher ovalbumin content contain oil droplets with multilayer adsorbed films. The steric stabilization due to adsorbed multilayers and the ability of rigid interfacial films to withstand external droplet pressures upon contact contributes to emulsion stability.