Rheology and structure of oleogelled water-in-oil emulsions containing dispersed aqueous droplets as inactive fillers

Abstract

The effect of dispersed aqueous droplets on the structure and rheology of rice bran wax (RBX) oleogels was investigated. Water-in-oil (W/O) emulsions containing up to 50 wt% water dispersed in canola oil were generated with polyglycerol polyricinoleate (PGPR) as the oil-soluble surfactant. The presence of both the RBX and PGPR resulted in oleogelled W/O emulsions stable against coalescence and phase separation for at least 28 days. The key contributor to emulsion structure and stability was the wax crystal network itself as the droplets behaved as an inactive filler. The oleogelled emulsions demonstrated structural weakening with increasing water content in terms of rigidity and thixotropic behaviour, both of which were attributed to the decrease in RBX content. Importantly, emulsion elastic modulus was near identical to its corresponding control where the dispersed phase was replaced by an equivalent wt% of continuous phase oil instead. Overall, this study demonstrated that even with dispersed droplets behaving as an inactive filler, it is possible to generate kinetically-stable oleogelled W/O emulsions with a high aqueous phase content.