46C-17 |
Use of caseinophosphopeptides as natural metal chelators to inhibit oxidative reactions in oil-in-water emulsions |
M. DÍAZ1, D. J. McClements, and E. A. Decker. (1) Department of Food Science, University of Massachusetts, Chenoweth Lab, Amherst, MA 01003 Transition metals are major prooxidants in many foods, including emulsions. Chelation of transition metals is a very effective method to decrease rancidity in such systems. Phosphorylated proteins and peptides originating from milk could provide a source of natural chelators to control lipid oxidation in food emulsions. Our objective was to evaluate the effect of caseinophophopeptides (CPPs) for their ability to inhibit lipid oxidation in oil-in-water emulsions. Casein was hydrolysated by trypsin and the digest, containing soluble peptides (CPP- I), was then ultrafiltrated to collect both phosphorylated and non-phosphorylated peptides smaller than 10,000 Daltons (CPP-II). CPP-III was enriched phosphorylated peptides obtained by selective precipitation of CPP-I. All the different peptide fractions were then freeze-dried and phosphorus content was measured using a standard inductively couple plasma (ICP) method. Brij-stabilized corn oil-in-water emulsions with added casein or CPPs were prepared and stored at 37 °C. Lipid hydroperoxides and headspace hexanal were measured for each treatment to follow lipid oxidation. Our results showed that there was a positive dose dependence on the amount of phosphorylated peptides added in the emulsions; i.e. the higher the concentration of CPP-III in the systems the slower the rates of hydroperoxides and hexanal formation. Also, casein and all the different peptides fractions (CPP I, CPP II, and CPP III) retarded the onset of peroxides and hexanal formation when compared to a control with neither protein nor peptides. The results suggest that casein and CPPs inhibit oxidative reactions of lipids in emulsions. This observed antioxidant activity of CPPs means they can be considered as potential ingredients for foods.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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