Effect of alcohol type on the formation of soybean oil-in-water nanoemulsions

Emulsions are mixtures of two immiscible liquids, one of them dispersed as droplets in the other. When the droplet size is in the range of 20 to 500 nm it is often a called nano-, mini- or submicron emulsion. Different methods have been proposed to prepare nano- emulsions, among them the transitional inversion (at fixed composition) so-called phase inversion temperature (PIT) method, commonly used in systems formulated with nonionic ethoxylated surfactants. In general, and in particular with other types of surfactants, the transitional inversion can be carried out by changing any other formulation like the salinity of the aqueous phase, the surfactant or surfactant mixture hydrophilicity or the co-surfactant effect (alcohol effect). The aim of this report was to obtain soybean oil-in-water nanoemulsions with a nonionic surfactant/soybean oil/water system through a low energy emulsification method. Emulsification was carried out by dilution, i.e., by a water-to-oil ratio change at constant temperature. The nanoemulsion drop size and stability are related to the alcohol type and the existence of a liquid crystalline phase during the emulsification process.