29B-2 |
Ability of chelators to alter the physical location and prooxidant activity of iron in oil-in-water emulsions |
Y. J. CHO1, D. J. McClememts2, and E. A. Decker2. (1) Dept. of Food Engineering, Sangju National Univ., 386 Gajangdong, Sangju, Gyeongbuk, 742-711, South Korea, (2) Dept. of Food Science, Univ. of Massachusetts, Amherst, 238 Chenoweth Lab., Box 31410, Amherst, MA 01003-1410 Prooxidants, such as iron, are naturally present in food emulsions at levels high enough to promote lipid oxidation. Many oil-in-water emulsions contain chelators that can alter lipid oxidation rates. One potential mechanism by which chelators can alter lipid oxidation is through their ability to alter the physical location of iron. The objective of this research was to evaluate the ability of chelators to influence the physical location and prooxidant activity of iron in oil-in-water emulsions. Ferric ions were dissolved in corn oil. Iron-containing lipids (20%) were then emulsified with 64 mM polyoxyethylene-10-lauryl ether by sonication. Sodium tripolyphosphate (STPP), ethylene diaminetetraacetic acid (EDTA), citric acid and whey protein isolate (WPI) were then added to the emulsion. Emulsion droplets and continuous phases were separated by centrifugation and quantification of ferric ions in the continuous phase was determined spectrophotometrically. Lipid hydroperoxides and headspace hexanal were determined to follow lipid oxidation. Continuous phase ferric ion concentration in the emulsions increased with increasing chelator concentrations (10-100 ¥ìM) and storage time (1-7 days). At pH 3.0, the continuous phase concentration of ferric ions was higher than pH 7.0 in the presence of chelators. Formation of lipid hydroperoxides and headspace hexanal in corn oil-in-water emulsions containing ferric ions decreased with increasing chelator concentrations (10-100 ¥ìM). The ability of the chelators to alter iron-promoted lipid oxidation in oil-in-water emulsions was STPP>EDTA>ctrate>WPI. These results indicate that chelators could alter the physical location and prooxidant activity of iron in oil-in-water emulsions. Understanding how chelators impact the prooxidant activity of iron could lead to the development of new antioxidant technologies.
Session 29B, Food Chemistry: Lipids, antioxidants and emulsifiers
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