Rheological investigation of pectin-based emulsion gels for pharmaceutical and cosmetic uses

Emulsion gels are structured emulsions suitable for different uses for their specific behaviour, which is strongly dependent on the characteristics of the gelled dispersing phase. Therefore, it is important to adopt the specific gelling agent to tune the final emulsion rheological behaviour properly. Pectin is extremely interesting among potential hydrophilic gelling agents owing to its specific characteristics. In the present work, four different low-methoxyl pectins were adopted to prepare gels to be used as the dispersing phase in cosmetic or pharmaceutical emulsion gels. The rheological characterisation of pectin gels, prepared at room temperature to avoid the damage to potential thermolabile components, was carried out with small amplitude oscillations. The obtained gels were used, together with a common non-ionic surfactant (Tween 60), to prepare olive oil emulsion gels suitable to design new cosmetic products. A simple empirical model, proposed to relate the emulsion complex modulus to the oil fraction and properties of the dispersing phase, has shown itself to be a potentially useful tool to design formulations with desired properties.