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 colour stabilizing and antioxidant effects of added tea catechins (TC) on susceptibility of fresh minced beef patties to lipid oxidation and colour stability during refrigerated (4℃) display under aerobic and modified atmosphere packaging (MAP, 80∶20, O2∶CO2) conditions were investigated. Fresh minced beef muscle (M. Longissimus dorsi) was supplemented with TC at levels of 0 (T0), 200 (T200), 400 (T400), 600 (T600), 800 (T800) and 1000 (T1000)mg/kg minced muscle. Treated samples were held in a refrig-erated (4C) display cabinet under aerobic or MAP conditions for 7 days. Lipid oxidation (TBARS) and proportion of metmyo-globin (MetMb) and oxymyoglobin (MbO2) were measured each day. TC-treated groups had consistently lower (p<0.01) lipid oxidation, compared to controls, for 2 days under both aerobic and MAP packaging conditions, thus showing the positive antiox-idant activities in minced beef. TC at levels of 200 (T200)mg/kg delayed the formation of MetMb under aerobic and MAP condi-tions. However, TC at levels greater than 400mg/kg meat did not show colour stabilizing effects in minced beef. The delay effect on discolouration was much more significant in MAP. The results obtained showed that TC not only improved lipid stability but also improved colour stability in minced beef. © 2005 Elsevier Ltd. All rights reserved.

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 C12 months) chicken breast and thigh meat were investigated. Dietary TC (TC200) showed inhibiting e?ects 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 oxi-dation, 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 e?ects of TC provide a plausible mechanism for the antioxidant e?ects of added TC in the in vitro meat system. © 2001 Elsevier Science Ltd. All rights reserved.

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.

The eects of dietary tea catechins (TC) supplementation at levels of 50 (TC 50), 100 (TC 100), 200 (TC 200), and 300 (TC 300 mg kg1 feed on susceptibility of chicken breast meat, thigh meat, liver and heart to iron-induced lipid oxidation were investigated Day old chicks (n=200) were randomly divided into six groups. Chicks were fed diets containing either basal (C), or-tocophery acetate supplementation at a level of 200 mg kg1 feed (VE 200), or TC supplementation for 6 weeks prior to slaughter. Lipi oxidation was assessed by monitoring malondialdehyde formation with 2-thiobarbituric acid (TBA) assay. TC supplementation a all levels exerted antioxidative eects for all tissues with the exception of 50mg kg1 feed for breast meat. TC supplementation a levels of 200 and 300mg/kg1 feed were found to be significantly (P<0.05) more eective in retarding lipid oxidation in all tissues compared to the control. TC supplementation at a level of 300mg kg1 feed was also found to be significantly (P<0.05) superior tvitamin E supplementation at a level of 200mg kg1 feed (VE 200) for oxidative stability in chicken thigh meat, but it was inferio to VE 200 in chicken liver and heart. TC supplementation at a level of 50 mg kg1 feed was found to be pro-oxidative in breas meat, but this did not occur in chicken thigh meat, liver and heart. The variation of TC antioxidative properties in dierent tissue may be explained by the uneven distribution of lipid, iron and TC accumulation in tissues. 2000 Elsevier Science Ltd. All right reserved.