67D-8 |
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W. CHAIYASIT1, C. B. Stanley2, D. J. McClements1, H. H. Strey2, and E. A. Decker1. (1) Dept. of Food Science, Univ. of Massachusetts, Amherst, Chenoweth Lab., Box 31410, Amherst, MA 01003-1410, (2) Polymer science and engineering, University of Massachusetts, Amherst, MA 01003 Edible oil contains surface active compounds that may form micro-heterogeneous environments, such as reverse micelles, that can alter the rate of chemical reactions. However, little is known about the role of reverse micelles in lipid oxidation of bulk oil. Our objective was to evaluate the ability of water, cumene hydroperoxide, oleic acid, and phosphatidylcholine to influence the reverse micelle structure produced by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in hexadecane. The influence of reverse micelle structure on iron catalyzed lipid oxidation was also determined in a reverse micelle system containing cumene hydroperoxide and methyl linolenate as the oxidizable substrates. The size and shape of the reversed micellar systems were investigated by small-angle X-ray scattering. Water contents in samples were determined by Karl Fischer titrations. Lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) were used to follow lipid oxidation in reverse micellar model systems containing oxidizable lipids. Our results showed that reverse micelles composed of AOT formed in hexadecane were spherical. The size of reverse micelles increased with increased water or phosphatidylcholine concentration. Addition of cumene hydroperoxide, and/or oleic acid into the system decreased reverse micelle size. Iron catalyzed oxidation of methyl linolenate in AOT reverse micelle system decreased with increasing water concentration as followed by lipid hydroperoxides and TBARS. Addition of phosphatidylcholine into the reverse micelle model decreased methyl linolenate oxidation compared to control and reverse micelles with added oleic acid. These results indicate that water, cumene hydroperoxide, oleic acid, and phosphatidylcholine can alter reverse micelle size and lipid oxidation rates. Understanding how these compounds influence reverse micelle structure and lipid oxidation rates could provide information on how to modify bulk oil systems to increase oxidative stability.
Session 67D, Food Chemistry: Lipid and carbohydrate chemistry
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