Effect of Reducing Oil Droplet Size on Lipid Oxidation in an Oil-in-water Emulsion

Abstract

Lipid oxidation processes were simulated for O/W emulsions with different oil-droplet sizes based on autocatalytic type rate expression in order to examine the effect of oil-droplet size on oxidation. Unoxidized lipid molecules were converted to oxidized ones momentarily or gradually, and the conversion occurred evenly or randomly in the droplets. When the oxidized molecules were formed momentarily, the droplet size scarcely affected the oxidation process, except for when the number of oxidized molecules was equal to or smaller than the number of oil droplets. In contrast, the oil droplet size significantly affected the oxidation process when the oxidized molecules were gradually and randomly formed at regular intervals. The oxidation was more retarded for the emulsions with smaller oil droplets. Because the latter case would be closer to a real system, the reduction in the oil droplet size in O/W emulsions is expected to increase the stability of lipids to protect against oxidation.