Post-mortem metmyoglobin reduction in fresh venison

The accumulation of metmyoglobin (MetMb) at the surface of meat during storage contributes significantly to its discolouration. Under appropriate conditions it may be possible to utilise residual meat MetMb reducing activity to maintain fresh colour. Venison meat colour stability is poorer compared with other species. Hence, we evaluated the capacity of completely discoloured venison (n = 12 animals) to reduce MetMb under anaerobic conditions in order to decipher more clearly the role MetMb reducing activity may play. The reducing capacity of venison (1 day, 3, and 6 weeks post-mortem), electrical stimulation, surface location (top and bottom) and rigor temperature (15 and 35 °C) on MetMb were evaluated. Surface MetMb decreased (P < 0.001) during storage while deoxymyoglobin increased (P < 0.001) demonstrating MetMb reduction. Metmyoglobin reduction was greater (P < 0.001) in venison which entered rigor at 15 °C, the reduction at the bottom surface of the steaks was greater (P < 0.001) compared with the top surface, and electrical stimulation had no affect (P > 0.05). These data demonstrate that metmyoglobin reducing activity occurs anaerobically in completely discoloured venison following storage display. The practical application for this finding needs to be determined.