46C-12 |
Ability of surfactant micelles to alter iron-promoted lipid oxidation in oil-in-water emulsions |
Y. J. CHO, Food Engineering, Sangjun National University, Sangju, Kyeongbuk, 742-711, South Korea, D. J. McClements, Department of Food Science, University of Massachusetts, Amherst, MA 01003, and E. A. Decker, Department of Food Science, Universlty of Massachusetts. Prooxidants, such as ferric ions are naturally present in food emulsions at levels high enough to promote lipid oxidation. Many oil-in-water emulsions contain surfactant micelles that can alter lipid oxidation rates. One potential mechanism by which surfactant micelles can alter lipid oxidation is through their ability to alter the physical location of iron through a solubilization process. The object of this research was to evaluate the ability of surfactant micelles to influence the physical location and prooxidant activity of iron in oil-in-water emulsions. Ferric ions were solubilized into hexadecane or corn oil. These iron-containing lipids (20%) were then emulsified with 17 mM polyoxyethylene-10-lauryl ether (Brij) by sonication. Emulsion droplets and aqueous phases were separated by centrifugation and quantification of ferric ions was determined spectrophotometrically. Lipid hydroperoxides and headspace hexanal were determined to follow lipid oxidation. The continuous phase ferric ion concentration in the emulsions increased with increasing surfactant micelle concentration (0.1-2.0%) and storage time (1-7 days). At pH 3.0, the aqueous phase concentration of ferric ions was higher than at pH 7.0. Similar solubilization trends were observed if 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 ferric ions decreased with increasing surfactant concentration (0.5-2.0%). These results indicate that surfactant concentration could alter the physical location and prooxidant activity of iron in oil-in-water emulsions. Understanding how surfactant micelles impact the prooxidant activity of iron could lead to the development of new antioxidative technologies.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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