Effect of Droplet Size on Autoxidation Rates of Methyl Linoleate and α-Linolenate in an Oil-in-Water Emulsion

Methyl linoleate and alpha-linolenate were used as representative n-6 and n-3 polyunsaturated fatty acid esters, respectively, to examine the effect of oil droplet size on autoxidative stability in oil-in-water systems. The emulsions, which were prepared via membrane emulsification and had a mean oil droplet size of approximately 1-30 mu m, and had a stable size during the autoxidation of each substrate at 55 degrees C. The autoxidation of methyl linoleate did not depend on oil droplet size during the entire process and that of methyl alpha-linolenate was independent of oil droplet size during the first half of the autoxidation process. However, the autoxidation rate of methyl alpha-linolenate proceeded faster in the emulsion with smaller oil droplet size during the last half of the autoxidation process.