The effects of dietary oregano essential oil and α-tocopheryl acetate on lipid oxidation in raw and cooked turkey during refrigerated storage

The effects of dietary oregano essential oil and α-tocopheryl acetate supplementation on the susceptibility of raw and cooked turkey breast and thigh meat to lipid oxidation during refrigerated storage for 9 days were examined. Thirty 12-week-old turkeys were divided into five groups and fed a basal diet containing 30 mg α-tocopheryl acetate kg−1 feed as control, or basal diet plus 200 mg α-tocopheryl acetate kg−1, or basal diet plus 100 mg oregano oil kg−1, or basal diet plus 200 mg oregano oil kg−1, or basal diet plus 100 mg oregano oil and 100 mg α-tocopheryl acetate kg−1, for 4 weeks prior to slaughter. Lipid oxidation was assessed by monitoring malondialdehyde formation in raw and cooked meat at 0, 3, 6 and 9 days of refrigerated storage, through use of a third-order derivative spectrophotometric method. Results showed that all dietary treatments significantly (P<0.05) increased the stability of both raw and cooked turkey meat to lipid oxidation compared with the control. Oregano oil at 200 mg kg−1 was significantly (P<0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg−1, equivalent to α-tocopheryl acetate at 200 mg kg−1, but inferior (P<0.05) to oregano oil plus α-tocopheryl acetate at 100 mg kg−1 each, which in turn was superior (P<0.05) to all dietary treatments, indicating a synergistic effect. Thigh muscle was more susceptible to oxidation compared with breast muscle in all treatments, although it contained α-tocopherol at significantly (P<0.05) higher levels.