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

Methyl linoleate and α-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 μm, and had a stable size during the autoxidation of each substrate at 55°C. The autoxidation of methyl linoleate did not depend on oil droplet size during the entire process and that of methyl α-linolenate was independent of oil droplet size during the first half of the autoxidation process. However, the autoxidation rate of methyl α-linolenate proceeded faster in the emulsion with smaller oil droplet size during the last half of the autoxidation process.