Location: Meat Safety & Quality ResearchTitle: Mitochondrial abundance and efficiency contribute to lean color of dark cutting beef
|MCKEITH, RUSSEL - Texas A&M Agrilife|
|King, David - Andy|
|GRAYSON, ADRIA - Texas A&M Agrilife|
|GEHRING, KERRI - Texas A&M Agrilife|
|SAVELL, JEFF - Texas A&M Agrilife|
Submitted to: Meat Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2016
Publication Date: 1/30/2016
Publication URL: http://handle.nal.usda.gov/10113/62945
Citation: Mckeith, R.O., King, D.A., Grayson, A.L., Shackelford, S.D., Gehring, K.B., Savell, J.W., Wheeler, T.L. 2016. Mitochondrial abundance and efficiency contribute to lean color of dark cutting beef. Meat Science. 116:165-173. doi:10.1016/j.meatsci.2016.01.016.
Interpretive Summary: Beef with dark lean is discriminated against and heavily discounted, resulting in substantial losses to beef producers. Although the mechanism causing the dark lean condition has long been known and results from stress induced muscle glycogen depletion, little is known about the factors predisposing some animals to producing dark beef. The present experiment examined the role of mitochondrial abundance and function as factors contributing to dark beef. Mitochondria in dark ribeye muscles were more abundant but less efficient compared to those from ribeyes with normal lean color. These results suggest that greater abundance of less efficient mitochondria may predispose animals to produce dark beef as a result of glycogen depletion.
Technical Abstract: Beef carcasses exhibiting four levels of dark cutting severity (DCS): Severe, Moderate, Mild, and Shady were compared to Control carcasses to investigate biochemical traits contributing to the dark cutting condition. Color attributes of Longissimus lumborum (LL) were measured after grading and during simulated retail display. Mitochondrial abundance and efficiency, bloomed oxymyoglobin, reducing ability, glycolytic potential, myoglobin concentration, and protein solubility and oxidation were determined. Glycolytic potential and lactate concentrations decreased (P < 0.05) as DCS increased. Residual glycogen was greater (P < 0.05) in steaks from Control carcasses compared to DCS classes. Generally, as DCS increased, longissimus lumborum steaks were darker less red in color (P < 0.05). Increased (P< 0.05) oxygen consumption and reducing ability coincided with greater myoglobin concentration and greater abundance of less efficient mitochondria as DCS increased (P < 0.05). These data suggest the dark cutting condition is associated with greater oxidative metabolism coupled with less efficient mitochondria resulting in depletion of glycogen during stress.