71 Impact of myoglobin oxygenation state at freezing on color stability of frozen and thawed beef

Myoglobin, when oxygenated, is bright red. The deoxygenated form (purple color) is unstable and can be oxidized to metmyoglobin (brown color). This research was conducted to determine if meat frozen in the oxygenated state could retain bright red color during frozen storage, and after thawing, during retail display. Steaks from 18 USDA Choice strip loins were randomly assigned to a myoglobin state [deoxymyoglobin (DeOxy; immediately packaged), low oxygenation (LoOxy; oxygenated for 30 minutes), and high oxygenation (HiOxy; packaged for 24 h in 80% O2)], frozen storage packaging method (vacuum packaged in oxygen permeable or impermeable film), and retail display after two months of frozen storage [0 d (frozen) and 1–7 d (thawed)]. Following storage, frozen steaks were analyzed for objective color (L*, a*, b*), subjective discoloration, and percent oxymyoglobin (via spectrometer). After thawing, steaks were evaluated throughout 7 d of retail display in oxygen-permeable film. For frozen steaks, there were no differences in discoloration (P>.05). The HiOxy steaks retained the highest percentage oxymyoglobin and highest (reddest) a* values after storage, regardless of packaging film. The lowest percent oxymyoglobin (PPPPP < .05). These data suggest that steaks frozen for two months in the high oxygenation state retain superior color appearance while frozen and during the first part of retail display. It is unknown if this advantage would be retained during longer frozen storage.