Antioxidative mechanisms of tea catechins in chicken meat systems

The effects of dietary tea catechins (TC) supplementation at levels of 50 (TC50), 100 (TC100) 200 (TC200), and 300 (TC300) mg/kg feed on oxidative stability and on protection of α-tocopherol (VE) in long-term frozen stored (-20 °C×12 months) chicken breast and thigh meat were investigated. Dietary TC (TC200) showed inhibiting effects on lipid oxidation equivalent to dietary α-tocopheryl acetate (VEA200) for long-term frozen stored chicken meat. The level of VE in long-term stored frozen chicken meat from TC dietary treatments (TC50, TC100, TC200 and TC300) was significantly (P<0.05) higher than that of meat from control diet containing no TC (C). The protective effects of TC against VE-depletion may partly elucidate the antioxidant activity of TC in vivo. The effects of TC on iron-induced docosahexaenoic acid (DHA)-incorporated L-α-phosphatidylcholine (PC) liposome oxidation, and on Fe²⁺-chelating and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging were also examined. Added TC showed significantly (P<0.05) higher antioxidant activity in oxidized DHA-PC liposomes than in controls. In addition to chelating effects on Fe²⁺, TC showed strong scavenging capacity for the DPPH free radical. The strong free radical-scavenging ability plus the iron-chelating effects of TC provide a plausible mechanism for the antioxidant effects of added TC in the in vitro meat system.