Ability of surfactant micelles to alter the physical location and reactivity of iron in oil-in-water emulsion.

The purpose of this research was to determine how surfactant micelles influence iron partitioning and iron-promoted lipid oxidation in oil-in-water emulsions. Lipids containing ferric ions were used to produce oil-in-water emulsions, and continuous-phase iron concentrations in emulsions were measured as a function of varying continuous-phase polyoxyethylene 10-lauryl ether (Brij) concentrations. Continuous-phase iron concentrations increased with increasing surfactant micelle concentrations (0.1-2.0%) and storage time (1-7 days). At pH 3.0, the concentration of continuous-phase iron was higher than at pH 7.0. Similar trends in iron solubilization by Brij micelles were observed when either hexadecane or corn oil was used as the lipid phase. Lipid oxidation rates, as determined by the formation of lipid hydroperoxides and headspace hexanal, in corn oil-in-water emulsions containing iron decreased with increasing surfactant concentrations (0.5-2.0%). These results indicate that surfactant micelles could alter the physical location and prooxidant activity of iron in oil-in-water emulsions.