Stabilization of liquid water‐in‐oil emulsions by modifying the interfacial interaction of glycerol monooleate with aqueous phase ingredients

Abstract

Glycerol monooleate (GMO)-stabilized liquid water-in-vegetable oil emulsions are difficult to stabilize due to the desorption of GMO from the water-vegetable oil interface toward the oil phase. This work improved the stability of GMOstabilized liquid 20 wt% water-in-canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond-forming agents. As a control, 20 wt% water-in-mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) were added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water-oil interface. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable during the week-long observation. The addition of hydrogen bond-forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond-forming agents interacted with GMO at the interface, thereby favoring their presence at the water droplet surface and significantly improving the stability of liquid W/CO emulsions. The knowledge developed in this research can be useful in utilizing GMO to stabilize liquid water-in-oil emulsions without using any fat crystal network.K E Y W O R D S emulsifier binding, glycerol monooleate, hydrogen bond-forming agents, low methoxy pectin, water-in-oil emulsion