Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2012
Publication Date: 10/1/2012
Citation: King, D.A., Shackelford, S.D., Kalchayanand, N., Wheeler, T.L. 2012. Sampling and aging effects on beef longissimus color stability measurements. Journal of Animal Science. 90:3596-3605.
Interpretive Summary: Inadequate lean color stability during retail display results in discoloration that leads to significant losses to the beef industry. We have previously identified substantial animal-to-animal variation in beef lean color stability, but further research to identify genetic markers affecting this trait, as well as development of prediction technology to manage variation, requires large numbers of samples be evaluated in a manner that is repeatable and representative of industry practices. The present research determined that color stability measurements are highly repeatable. Furthermore, a sampling method that can be cost-effectively applied to large numbers of carcasses was determined to be representative of animal variation in top loin steaks that had been aged for moderate (14 days) or extensive (35 days) periods. These results indicate appropriate data can be collected on a steak removed from the carcass at the time of grading to identify approaches to improve lean color stability.
Technical Abstract: The present study was conducted to determine the repeatability of color stability measurements and to evaluate relationships among color stability data collected under differing sampling and aging protocols. Beef carcasses (n = 100) were selected at grading in a commercial facility, after which a LM steak was removed from the 13th rib of each carcass and immediately placed in simulated retail display. Steaks were removed from the remainder of each loin after 14 (duplicate) and 35 d of aging and placed in display. Color attributes [L*, a*, b*, hue angle, chroma, K/S572/K/S525, and overall color change (delta E)] were determined on d 0, 1, 4, 7, and 11 of display. Duplicate 14-d aged steaks differed (P < 0.05) initially with regard to L*, b*, hue angle, chroma, K/S572/K/S525, and delta E. However, changes in these attributes during display were equivalent in the duplicate steaks. Furthermore, repeatability estimates were high for all attributes, particularly when measured late in the display period (R = 0.55 to 0.97 on d 4, 7, and 11 of display). Differences in the trends associated with color change of steaks removed from the carcass after grading and those aged for 14 d were generally insignificant. Changes in color attributes of steaks aged for 35 d before simulated retail display generally were much more rapid than those obtained after grading or those aged for 14 d. Despite differences in the rate of discoloration during simulated retail display, color attributes were moderately to highly correlated (P < 0.05) between aging treatments, though the degree of correlation between attributes varied across days of display. In steaks collected after grading and those aged for 14 d, the greatest correlation was observed in the latter part of the display period with coefficients ranging from 0.61 to 0.94 on d 4, 7, and 11 of display. The greatest correlation between steaks aged for 14 d and those aged for 35 d were detected in the middle portion of the display period, presumably because many steaks aged for 35 d had reached an ultimate level of discoloration by d 11 of display with correlation coefficients ranging from 0.51 to 0.95 on d 4 and 7 of display. Thus, these results indicate that color stability data is highly repeatable and that, although aging impacts color-life, animal variation is consistent across aging times. Furthermore, steaks obtained from carcasses after grading can provide color stability evaluations applicable to steaks from aged subprimals.