Evidence of iron association with emulsion droplets and its impact on lipid oxidation

zeta-Potential measurements were used to evaluate conditions that influence iron-emulsion droplet interactions. Fe2+ and Fe3+ associated with sodium dodecyl sulfate (SDS, anionic) but not with dodecyltrimethylammonium bromide(DTAB, cationic) and polyoxyethylene 10 lauryl ether (Brij, nonionic) stabilized hexadecane emulsions. Association of iron with SDS-stabilized emulsion droplets increased with decreasing pH and decreased in the presence of EDTA, phytate, and NaCl. Oxidation of the SDS-stabilized salmon oil emulsion increased as iron-emulsion droplet interactions increased. EDTA concentrations (greater than or equal to 1000 mu M) that resulted in no detectable association of iron (500 mu M) with the emulsion droplets were the most effective at inhibiting oxidation. The ability of iron to associate with emulsion droplets seems to be an important factor in the promotion of lipid oxidation; therefore, techniques that control iron's physical location could be effective in controlling oxidation.