Stabilization of food-grade liquid water-in-vegetable oil emulsions by modifying emulsifier interactions at the oil-water interface

Dérick Rousseau, Supratim Ghosh

Ryerson University; University of Saskatchewan

Maria Romero(1,2), Dérick Rousseau(3), and Supratim Ghosh(4)

(1)Dept. of Food and Bioproduct Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Canada
(2)Escuela Superior Politécnica del Litoral, ESPOL, Facultad de Ingeniería en Mecánica y Ciencias de la Producción, Ecuador.
(3)Ryerson University, Canada
(4)University of Saskatchewan, Canada

Food-grade water-in-vegetable oil (W/VO) emulsions are difficult to stabilize with only glycerol monooleate (GMO), which desorbed from the water-VO interface due to their stronger hydrogen bonding with VO fatty acid carboxylic groups. We hypothesized that stronger hydrogen bonding towards the aqueous phase would enhance GMO's binding to the interface, thereby providing stability to the emulsion. Therefore, carboxylic group donating agents such as citric acid (CA), ascorbic acid (AA) were added to the aqueous phase to stabilize W/VO emulsions with GMO. Various concentrations of CA, AA and NaCl were added to the aqueous phase. W/VO emulsions (20/80wt%) were prepared by high-pressure homogenization. Emulsions were stored for seven days; the stability was identified by visual observation, sedimentation, viscoelasticity, microstructure, and droplet size. A minimum of 0.125wt% NaCl was needed for emulsion stability when no CA or AA was present. The addition of CA or AA improved stability without the presence of salt. All emulsions behaved like weak gels, where G' increment with NaCl. The addition of acids significantly increased G' at most concentrations. After seven days, the presence of CA, G' remained unchanged, except a rise was observed at high NaCl. With AA, a decrease in G' was observed, indicating droplet destabilization, except an increase, was found at 1wt% salt and 5wt% AA. Microscopy showed droplet aggregation at low NaCl without the acids. In the presence of the acids, no droplet aggregation was observed. This study demonstrates stable liquid W/VO emulsions can be developed based on emulsifier interactions at the oil-water interface.