SYNERGETIC EFFECT OF SUCROSE AND ETHANOL ON FORMATION OF TRIGLYCERIDEMICROEMULSIONS

The phase behavior of soybean oil, a nonionic surfactant (ethoxylated monodiglycerides) and an aqueous phase of water containing ethanol, an d sucrose was investigated at 35 and 40-degrees-C. A minimum concentra tion of 20 wt% ethanol was required for the formation of isotropic sol utions. Addition of sucrose to the aqueous phase decreased the amount of ethanol required to form these solutions. The solubilization mechan ism of the oil was investigated by small angle x-ray diffraction and p olarized light microscopy. A stable lamellar liquid crystalline phase was formed for a mixture of 75/25 surfactant/sucrose solution (2.5 wt% sucrose). This phase was destabilized with increased concentrations o f sucrose and liquid crystalline phases having hexagonal structures we re favoured at 8.75 wt% sucrose. At a ratio of 55/45 wt% of surfactant /sucrose solution (9 wt% sucrose) hexagonal structures were formed and could be destabilized or destroyed by addition of ethanol. The concep t of stabilization and destabilization of liquid crystalline mesophase s was applied to the solubilization of triglycerides in aqueous soluti ons. Two microemulsion regions were identified; oil-in-water (L1) and water-in-oil (L2) in systems containing soybean oil, ethoxylated monod iglycerides, and 20 wt% ethanol solution. At 55/45 wt% surfactant/20 w t% ethanol solution, 7.5 wt% of soybean oil was solubilized. Addition of 10, 20, and 30 wt% sucrose, at the same ratio of surfactant to etha nol solution, increased the solubility of the oil to 9, 13.5, and 18 w t% respectively. In addition, the size of the L1 phase increased and m oved to the aqueous corner of the phase diagram and the size of the L2 phase decreased.