PLs sequester metals and/or donate hydrogen atoms from their nitrogen-containing functional groups such as choline or ethanolamine to radicals (Saito and Ishihara 1997), resulting in decreased oil oxidation (Choe and Min 2006. On the other han PLs can elevate autoxidation and chlorophyl- photosensitized oxidation of purified oil which does not have any metals (Yoon and Min 1987: Lee and Choe 2009). Since PLs are located mainly at interfaces with their nonpolar fatty acid tails facing the oil phase and a polar head facing the water phase xu and others 2011). they are able to decrease the surface tension of oil and increase oxygen diffusion from the headspace, resulting in acceleration of oil oxidation (Choe and Min 2006). Therefore, the reduction of iron-catalyzed autoxidation of oil by added soybean lecithin could have been largely attributed to iron chelation by PLs. Iron increases oil oxidation by accelerating decomposition of hydroperoxides into radicals (Choe and Miin 2006). In addition, donation of hydrogen to radicals from functional groups such as choline or ethanolamine could have contributed to the reduction of oil oxidation. Although PLs can also donate hydrogens to radicals under chlorophyll-photosensitized oxidation. increased oxygen diffusion by PLs could have resulted in a higher singlet oxygen production. which was more predominant than radical avenging by hydrogen donation in chlorophyll-photosensitized oxidation. Thus. addition of soybean lecithin had no significant effect on the chlorophyll-photosensitized oxidation of the canola oil emulsions.