The comparative antioxidant activity of added tea catechins on susceptibility of cooked and overwrapped red meat (beef and pork), poultry (chicken, duck and ostrich) and fish (whiting and mackerel) to lipid oxidation was investigated. Fresh meats, poultry and fish, purchased from a local market. were trimmed to remove bones, skin and visible fat and minced through a 4-mm plate. The minced muscle from each species was treated with either l% NaCl (S), 300mg tea catechins kg-1 minced muscle (TC) or 1% NaCI plus 300 mg tea catechins kg-1 minced muscle (TCS). Control minced muscle samples (C) contained neither NaCI nor tea catechins. Patties (50g), prepared from treated and untreated minced muscle. were cooked until the core temperature reached 750C, cooled down to room temperature and held in a refrigerated (40C) and illuminated (616 lux) display cabinet for 10 days. Oxidative stability (TBARS) was measured at 3-day intervals. The susceptibility of cooked patties to lipid oxidation was closely related to lipid con-tent, concentration of unsaturated fatty acids and presence of iron in different species. Addition of NaCI to raw minced muscle significantly (P<0.05) promoted lipid oxidation for cooked patties regardless of species sources. Tea catechins added at a level of 300mg kg-1 minced muscle significantly (P<0.01) inhibited the pro-oxidation caused by NaCI and controlled lipid oxidation for all cooked muscle patties examined. Tea catechins at concentrations greater than 300 mg kg-1 were necessary to reduce oxidation for mackerel patties containing high levels of lipids and unsaturated fatty acids. The high affinity of tea catechins for the lipid bilayers of muscle and the radical scavenging abilities of tea catechins may be possible mechanisms to explain the oxidative stabilitv in cooked muscle foods.

The antioxidative eect of dietary tea catechins (TC) supplementation at levels of 50, 100, 200 and 300 mg kg1 feed on susceptibility of chicken breast and thigh meat to lipid oxidation during frozen (20C) storage for 9 months was investigated. Day-old chickens (Cobb 500, n=200) were randomly divided into six groups. Chickens were fed a basal diet containing 20 mg α-tocopheryl acetate kg1 feed as control, or a vitamin E supplemented diet (basal diet plus 200 mg α-tocopheryl acetate kg1 feed), or TC supplemented diets (basal diet plus 50, 100, 200 or 300 mg TC kg1 feed) for 6 weeks prior to slaughter. Lipid oxidation (TBARS) was assessed after 0 and 10 days of refrigerated display (4C) following 1, 3, 6, and 9 months of frozen (20C) storage. TC supplementation at all concentrations showed antioxidative eects for both breast and thigh chicken meat during the 9 months of frozen storage compared to the control sample. TC supplementation at levels of 200 and 300 mg kg1 feed were more eective (P<0.05) in delaying lipid oxidation in all meat samples compared to the control. TC supplementation at a level of 200 mg kg1 feed showed antioxidant activity equivalent to-tocopheryl acetate fed at the same level up to 3 months of frozen storage. For long-term frozen storage up to 9 months, however, TC supplementation at 300 mg kg1 feed was required as a replacement for α-tocopheryl acetate at a level of 200 mg kg1 feed. The results obtained showed a long-term antioxidative eect exhibited by dietary tea catechins on chicken meat during frozen storage and demonstrated that tea catechins are eective alternatives to vitamin E as natural dietary antioxidants. 2000 Elsevier Science Ltd. All rights reserved.