The effect of oxygen level and exogenous α-tocopherol on the oxidative stability of minced beef in modified atmosphere packs

The effect of oxygen level (20, 40, 60 and 80%) in modified atmospheres on the oxymyoglobin content of intact and minced beef (M. semimembranosus, SM) was evaluated. There was no significant difference in the oxymyoglobin content of minced SM stored for up to 4 days in modified atmosphere packs containing 20, 40, 60 or 80% O-2. After 7 days, oxymyoglobin in minded SM decreased significantly (P less than or equal to 0.05) with decreasing oxygen level but by day 10 all samples had similarly low oxymyoglobin contents. Lipid oxidation increased significantly (P less than or equal to 0.05) between day 7 and 10 of storage in minced SM stored in modified atmospheres containing 40, 60 or 80% O-2 Oxymyoglobin and lipid oxidation occurred in intact SM but the extent of oxidation was lower than for minced SM. Exogenous alpha-tocopherol, dispersed in olive oil and added to minced SM (300 and 3000 mg alpha-tocopherol/kg lipid), had no significant effect on Hunter 'a' values when the samples were stored in low (20%) or high (80%) oxygen atmospheres. Exogenous alpha-tocopherol addition led to a significant reduction in lipid oxidation (P less than or equal to 0.05) in minced SM stored in high but not in low oxygen atmospheres. (C) 2000 Elsevier Science Ltd. All rights reserved.