Incorporate oxidatively stable omega-3 fatty acids into foods.

Oil-in-water emulsions offer unique opportunities for incorporating omega-3 fatty acids into functional foods. Omega-3 fatty acids are helpful in preventing a range of human diseases. For this reason, they are excellent candidates as ingredients in functional foods. However, the ability to successfully add omega-3 fatty acids to different products is limited because the omega-3s are highly susceptible to oxidation.

Scientists at the University of Massachusetts and elsewhere examined the oxidative stability of omega-3 fatty acids in emulsions coated with lecithin alone or with a lecithin-chitosan multilayer system. The researchers also determined the impact of mixed tocopherol and ethylenediaminetetraacetic acid (EDTA) on the oxidative stability of liquid and freeze-dried emulsions. It appears that tuna oil-in-water emulsions containing droplets stabilized by lecithin-chitosan membranes that have EDTA and mixed tocopherol could be used as an ingredient delivery system for incorporating oxidatively stable omega-3 fatty acids into products.

The researchers prepared tuna oil-in-water emulsions stabilized by lecithin, as the primary emulsion, by homogenizing oil and an emulsifier solution at 5 wt% tuna oil, 1 wt% lecithin and with a 100 mM acetate buffer at pH 3.0. A secondary, multilayer emulsion stabilized by lecithin and chitosan was formed by diluting the primary emulsion with an aqueous chitosan solution at 5 wt% tuna oil, 1 wt% lecithin, using a 100 mM acetate buffer and 0.2 wt% chitosan. Primary and secondary emulsions were prepared in the absence and presence of 20 wt% corn syrup solids.

Tuna oil-in-water emulsions containing droplets stabilized by lecithin-chitosan membranes were able to produce cationic emulsion droplets that decreased the oxidation of lipids by decreasing iron-lipid interactions. Adding EDTA further increased the oxidative stability of the emulsions in both liquid and dried systems. Mixed tocopherol isomers were less effective and prooxidative at the early stage of storage. The combination of EDTA and mixed tocopherol isomers was more effective at inhibiting lipid oxidation than EDTA or the mixed tocopherol isomers alone.

Further information. D. Julian McClements, Department of Food Science, University of Massachusetts, Amherst, 238 Chenoweth Laboratory, Box 31410, Amherst, MA 01003; phone: [phone]; email: [e-mail].