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J. GALLAHER, J. N. Coupland, D. G. Peterson, and R. F. Roberts. Dept. of Food Science, Pennsylvania State Univ., 126 Borland Lab., University Park, PA 16802 Dietary intake of the n-3 polyunsaturated fatty acids (PUFA) results in beneficial effects on neural and visual development and the prevention of diseases such as coronary heart disease. Nevertheless, the current Western diet is inadequate in n-3 PUFA intake. Dairy products supplemented with physiologically significant amounts of n-3 PUFA would provide a dietary source in a form widely consumed and therefore likely to have a useful impact on health outcomes. However, utilization of n-3 PUFA in food products is limited due to their oxidative instability. The goal of the research was to evaluate the oxidative stability of an algal oil-in-water (O/W) emulsion dispersed in water, or fluid milk of varying fat contents and with or without added antioxidants. Algae O/W emulsions (25 wt%) were emulsified in 2 wt% polyoxyethylene sorbitan monolaurate and sodium acetate/imidizole buffer (pH 7) solution, and dispersed in the appropriate reaction matrix (water, skim milk, 2% milk, whole milk) to a final concentration of 5 wt% algae oil. Samples were allowed to oxidize in the dark at 32¨¬C, and oxidative deterioration was assessed by lipid hydroperoxide and headspace propanal methods. All of the milk samples, independent of their milk fat content, were stable compared to aqueous samples. The extent of oxidation was unaffected when sodium azide (200 ppm) was added to inhibit microbial growth. Added iron (100 ppm) accelerated the oxidation rate in the aqueous samples, but had no effect on the milk samples. Milk with added protein antioxidants (0.8 wt%) [i.e., sodium caseinate, whey protein isolate (WPI) and thermally denatured WPI] had minimal effects whereas added EDTA and ascorbic acid (160 ppm) were effective antioxidants. These results suggest that milk is highly antioxidant, likely due to the iron binding of casein. This antioxidant effect may facilitate the incorporation of ¥ø-3 PUFAs into dairy foods.
Session 46, Dairy Foods: General
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