Lipid and protein oxidation of broiler meat as influenced by dietary natural antioxidant supplementation

Natural tocopherols (TC), rosemary (RO), green tea (GT), grape seed, and tomato extracts were supplemented in single and in combinations at total concentrations of 100 and 200 mg . kg(-1) of feed in a 4% linseed oil-containing diet to investigate the oxidative stability of broiler breast muscle. Supplementation with 300 mg . kg(-1) of synthetic antioxidants alone and synthetic antioxidants with alpha-tocopheryl acetate at a concentration of 200 mg . kg(-1) (100 IU) feed was used as a control. Fresh patties were prepared and stored under light at 4 C. After freezing for 8 mo and overnight thawing, 3 other patties were prepared and similarly stored under light at 4 C. During display, samples were evaluated for oxidative stability measurements. For lipid oxidation, the treatment with synthetic antioxidants and 200 mg . kg(-1) of alpha-tocopheryl acetate yielded the lowest TBA reactive species (TBARS) values. For TC, grape seed, and tomato extracts, TBARS values for 100 mg . kg(-1) were higher (P < 0.05) than 200 mg . kg(-1) treatments, whereas no differences (P > 0.05) in TBARS values were observed for RO between 100 and 200 mg . kg(-1). In contrast, GT showed higher TBARS values at 200 mg . kg(-1). Administration of combinations of TC, RO, and GT did not reveal synergistic effects but confirmed the increase in TBARS values with increasing doses of GT. No differences (P > 0.05) among the different antioxidant treatments were detected for protein oxidation. The muscle alpha-tocopherol content linearly responded to the feed alpha-tocopherol content and thus there were no indications for a sparing effect on alpha-tocopherol from other antioxidant treatments. In summary, dietary natural antioxidant extracts were less effective than the treatment with synthetic antioxidants combined with alpha-tocopheryl acetate for protecting against oxidation, but there were marked differences between different natural antioxidant extracts.