30A-12 |
Anti- or pro-oxidative effects of polyphenolic compounds in oil emulsion by making chelate with catalytic metals |
Y. YOSHIE1, M. Takayanagi, and T. Suzuki. (1) Department of Food Science and Technology, Tokyo University of Fisheries, 4-5-7 Konan, Minato, Tokyo, 108-8477, Japan There is great interest in plant polyphenolic compounds because of their potential role such as cancer chemopreventive agents and chronic disease protector. Their beneficial effect is considered to be mainly due to their antioxidant and chelating activities. Many researchers explained the antioxidative effect of polyphenolic compounds by the decrease of several oxidation marker values, but their mechanism is still unclear. Our objective was to estimate the function of polyphenolics in oil oxidation system by using metal chelating or scavenging effects as markers. Fish oil emulsion was incubated with polyphenolics at the presence of iron or copper ion at 50 C for 0-24 hours. Standard solutions of polyphenolic compounds or tea concentrate was used as an anti-oxidant or a pro-oxidant. Lipid oxidation was analyzed by peroxide value (POV). The chelating effect of Fe2+ was analyzed using Forrozine solution and measuring chelate by spectrophotometer. Ferrous ion in the oil emulsion was analyzed using 2,2-dypyridyl in methanol/buthanol solution then measuring Fe2+ by spectrophotometer, and copper ion was analyzed by ion chromatography. Green tea concentrate including catechin, epicatechin, epigallocatechin, epigallocatechin gallate, epicatechin gallate reduced POV and made chelate with Fe2+. Catechin and rutin alone increased POV and they did not make chelate. Gallic acid and catechol alone did not affect both POV and metal chelate. When we used FeCl3 as a catalyst, tea concentrate showed pro-oxidant activity to oil emulsion and it also changed Fe3+ to Fe2+. Polyphenolic compounds from certain mixture like tea concentrate may act both as an anti-oxidant and a pro-oxidant depending on the composition and ratio of polyphenolic compounds. Each polyphenolic and related compound has each characteristic to affect lipid oxidation, to make metal chelate, and to scavenge metal ions. Therefore, we should make further research to find out most effective food complex as an anti-oxidant.
Session 30A, Food Chemistry: Lipids
|