The health benefits of conjugated linoleic acid (CLA), a functional lipid with anti-cancer, anti-obesity, and hypotensive activity, have garnered increasing attention. The current study was conducted to determine the oxidative stability of CLA in the form of triacylglycerol (CLA-TAG) and phosphatidylcholine (CLA-PC) at the sn-2 position. Oxidation was performed at 30°C or 40°C in the dark. Hydroperoxides, as the primary oxidation products, were analyzed using diphenyl-1-pyrenylphosphine. Thiobarbituric acid reactive substances (TBARS) and volatile compounds were monitored as secondary oxidation products. The results suggest that CLA-PC was more stable against oxidation than CLA-TAG from the perspective of suppression of the generation of hydroperoxides and TBARS. However, CLA-PC produced more volatile compounds than CLA-TAG. We suggest that choline was released during the oxidation of CLA-PC, and acted as an antioxidant. The ensuing reaction between choline and hydroperoxide induced the generation of volatile compounds such as pentanal, hexanal, and heptanal.
Keywords: conjugated linoleic acid; oxidation stability; phosphatidylcholine; triacylglycerol.