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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #294512
Title: Influence of mitochondrial efficiency on beef lean color stability

Author
item MCKEITH, RUSSELL - Texas A&M University
item King, David - Andy
item GRAYSON, ANDREA - Texas A&M University
item Shackelford, Steven
item SAVELL, JEFF - Texas A&M University
item Wheeler, Tommy

Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2013
Publication Date: 6/16/2013
Citation: Mckeith, R.O., King, D.A., Grayson, A.L., Shackelford, S.D., Savell, J.W., Wheeler, T.L. 2013. Influence of mitochondrial efficiency on beef lean color stability. [abstract] American Meat Science Association Conference Reciprocal.p. 82.

Interpretive Summary:

Technical Abstract: Loss of electrons in the electron transport chain has been implicated as a source of variation in feed efficiency of meat producing animals. The present study was conducted to evaluate the effects of electron loss during electron transport on beef lean color stability. Beef carcasses (n = 91) were selected from a commercial beef processor and longissimus lumborum pH and marbling score were determined as the carcasses were presented for grading. Beef, loin, strip loin subprimals were aged until 13 d postmortem, when longissimus lumborum steaks were cut for simulated retail display. Instrumental color attributes [lightness (L*), redness (a*), yellowness (b*), hue angle] were determined on d 0, 1, 4, 7, and 11 of simulated retail display. Overall color change from d 0 ('E) was calculated for d 1, 4, 7, and 11 of simulated retail display. Additional steaks were used for determination of electron loss from the electron transport chain, oxygen consumption, metmyoglobin reducing activity, glycolytic potential, and myoglobin concentration determination. Electron loss was determined as the percentage increase in fluorescence units resulting from incubating (37°C for 20 minutes) isolated mitochondria in the presence of 2’-7’ dichlorfluorescin diacetate with succinate as a substrate for electron transport. Longissimus lumborum steak lightness on d 0 of display was positively correlated (P < 0.05) to electron loss (r = 0.28), marbling score (r =0.40), and glycolytic potential (r = 0.25). Myoglobin concentration (r = -0.41), metmyoglobin reducing activity (r = -0.51), oxygen consumption (r = -0.41), and muscle pH (r = -0.29), were negatively correlated (P < 0.05) to d 0 L* values. Redness (a*) on d 0 of display was negatively correlated (P < 0.05) to metmyoglobin reducing activity (r = -0.21), oxygen consumption (r = -0.28), and muscle pH (r = -0.35). Overall color change during 11 d of simulated retail display was associated (P < 0.05) with increased electron loss (r = 0.35) and decreased metmyoglobin reducing activity (r = -0.21), oxygen consumption (r = -0.22), and muscle pH (r = -0.32). Increased electron loss was associated (P < 0.05) with decreased metmyoglobin reducing ability (r = -0.23) and muscle pH (r = -0.39). Increased electron loss was also associated (P < 0.05) with increased glycolytic potential (r = 0.24) and marbling score (r = 0.26). These data suggest that greater electron loss is associated with decreased metmyoglobin reducing activity and, consequently, reduced beef lean color stability. Electrons lost during electron transport form reactive oxygen species which then must be reduced by the cell. Lower reducing ability associated with increased electron loss may be due to the NADH pool being depleted while reducing the reactive oxygen species. Another mechanism may be the oxidative damage of enzymes associated with metmyoglobin reduction by reactive oxygen species. Moreover, increased electron loss was associated with greater glycogen stores (evidenced by glycolytic potential) and reduced muscle pH, which contributed to increased lightness at the beginning of simulated retail display. Thus, it appears that reduced mitochondrial efficiency influences beef lean color and color stability. Increased feed efficiency through mitochondrial efficiency may result in fewer losses associated with discoloration of beef products at retail. Key words: Beef; color; color stability; electron transport; mitochondria