Understanding the Meat Color Attributes by Direct Electrochemistry of Myoglobin Films on Electrodes

Tuesday, 7 October 2014: 09:00
Expo Center, 2nd Floor, Delta Room (Moon Palace Resort)
S. Krishnan, R. Nerimetla, C. Walgama, and R. Ramanathan (Oklahoma State University)
Protein film electrochemistry (PFE) is a unique method with high simplicity to obtain mechanistic information about complex biological electron transfer and catalytic processes. The emerging applications of PFE are in the development of selective biosensors, biofuel production, renewable energy processes, green biocatalytic systems, and biomedical tools.[i],[ii],[iii] Along this line, we are exploring the novel utilization of heme-protein electrochemistry to understand the meat color qualities. Myoglobin (Mb) is a muscle protein predominantly responsible for meat color. Mb can exist in three different forms namely deoxy-, oxy-, and metmyoglobin. The extent of oxymyoglobin (Mb-FeII-O2) state mainly influences the characteristic red color of meat. On the other hand, the oxidation of oxy- or deoxymyoglobin leads to discoloration of meat or metmyoglobin (Mb-FeIII) accumulation.

Our objective was to investigate the kinetics of metmyoglobin reduction and oxymyoglobin formation using myoglobin model and examine its relevance to meat color properties. For our initial electrochemical analysis, we have chosen three meat related pH conditions such as pH 7.4  (physiological muscle), pH 6.4 (stress-out animal muscle), and pH 5.6 (typical postmortem muscle) and investigated the rates of Mb-FeIII  reduction and Mb-FeII-O2 formation using Mb-films adsorbed on graphite electrodes. We observed that under the physiological muscle pH condition, the rates of Mb-FeIII reduction and the subsequent formation of Mb-FeII-O2 were highly favored in comparison to the low acidic pH conditions. Our electrochemical results correlated well with the prior biochemical and redox-titration studies that reported the faster discoloration of meat with lowering pH conditions.[iv],[v] Our investigation suggests that myoglobin-PFE is simple, inexpensive, rapid, and powerful in probing atomic level redox-properties, and thus a valuable tool to predict meat color.


Acknowledgements. This work was supported by the Oklahoma State University.

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