Soy oil microemulsions has been optimized for systems made of phosphated oleyl ether 3EO as surfactant, oleic acid, diethyleneglycol monoethyl ether, and water. The soy oil solubilization has been estimated as a function of different ratios between surfactant/oleic acid (5/95, 10/90, 15/85, and 20/80) and water/glycol (4/1, 2/1, 1/1, 1/2, and 1/4). The maximum simultaneous solubilization of soy oil and hydrophilic phase (water plus glycol) in ratios 3/1, 1/1, and 1/3 (besides the 1/0 and 0/1) was considered. In order to display the widest microemulsion area, the better ratios surfactant/oleic acid were 10/90, 15/85, and 20/80 when water and glycol ratios were 1/2 and 1/4. For these systems, the transition between W/O, bicontinuous and O/W microemulsions were followed through electrical conductivity changes.

The authors acknowledge the financial support from CICYT (CTQ2004-00773 Project).

5 pages, 5 figures.-- Printed version published Nov 2007.

Peer reviewed