Research Accomplishment Reports 2007

Elucidating Aldehyde-induced Redox Instability in Carboxymyoglobin

S. Suman
Department of Animal and Food Sciences

 

Project Description

Improved meat color stability could save the US meat industry more than $1 billion annually. The ferrous forms of myoglobin - oxymyoglobin and carboxymyoglobin, provide desirable cherry-red color for fresh meat. Formation of brown metmyoglobin, accelerated by lipid oxidation, is associated with meat discoloration and results in price reductions. Previous investigations to characterize lipid oxidation-induced meat discoloration were carried out utilizing oxymyoglobin, the redox form responsible for consumer preferred cherry-red color of traditionally packaged and conventionally bloomed meat. Until 2004, the only cherry-red colored redox form relevant to the US meat industry was oxymyoglobin. Situations have changed as carbon monoxide (CO) is now allowed for use in case-ready meat packaging systems in the US.

Till date, meat color researchers have not addressed the molecular basis of carboxymyoglobin stability, especially in the presence of reactive lipid oxidation products. This fundamental study was initiated in 2007, with the objective to elucidate the effects of aldehyde adduction on carboxymyoglobin stability. We have standardized the methods to prepare 100% carboxymyoglobin in conditions relevant to meat processing and to differentiate the spectra of carboxymyoglobin from those of oxymyoglobin samples. In addition, experiments were conducted to assess oxidative stability of carboxymyoglobin. The resistance of carboxymyoglobin against autoxidation was greater than oxymyoglobin. Currently, additional experiments are underway to evaluate aldehyde adduction-induced protein oxidation employing mass spectrometry.

Impact

Maintaining myoglobin in its cherry-red redox state (carboxymyoglobin or oxymyoglobin) is very critical to consumer acceptance of meat. Our results demonstrated that the cherry-red color of carboxymyoglobin is more stable than oxymyoglobin. However, color deterioration has been reported during retail display of meat stored in CO containing modified atmosphere packaging. Potential reason for this discoloration could be lipid oxidation. Understanding lipid oxidation: carboxymyoglobin interactions would be beneficial for meat industry and regulatory agencies to clearly define the color shelf-life of CO-treated meat. Moreover, this information could be used to determine the 'Best before Date' for CO-treated meat.