Quercetin increases antioxidant activity of soy lecithin in a triolein model system

Antioxidative activities of native soy lecithin and mixtures of quercetin and lecithin (1:1, w/w) in the protection of triolein models stored under accelerated oxidative conditions for 15 days in the dark at 60 degrees C were studied. The progress of oxidation was followed by recording the ultraviolet absorptivity and measuring the formation of oxidative products (peroxide value (PV)). The antiradical action of different models against DPPFI radicals was screened during Shaal oven test. The factors influencing the oxidative stability of different triolein models were also discussed. Inverse relationships were noted between PVs and oxidative stabilities at termination of the storage. Absorptivity at 232 and 270 nm in models containing lecithin increased gradually with the increase in time, due to the formation of conjugated dienes and polyenes. In general, oxidative stabilities of quercetin-lecithin-enriched models were better than in models containing lecithin or quercetin alone, most likely as a consequence of synergism between polar lipids and quercetin. Moreover, increases in concentration of quercetin-lecithin mixture resulted in an increase in its antioxidative activity. These results may be useful for improving the antioxidative activity and health impact of commercial lecithin in different food applications. (C) 2007 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.