Background 

Beef retailers are seemingly hesitant to age beef for more than 14 days prior to placing it in the retail case because product “freshness” is reduced, and a shorter display life may be realized.  

A more definite understanding of the effects of postmortem aging on the retail display life of USDA Commodity Choice and Select cuts that are most likely to appear in retail supermarkets could lead to a more extensive implementation of aging beef products destined for retail and ultimately decrease the incidence of unacceptably tough steaks sold in retail while optimizing tenderness without sacrificing time in retail display. This is especially relevant with the world’s largest retailer, Wal-Mart, improving the quality of the beef products that they are selling and accompanying them with a “guaranteed satisfaction, money-back” claim. With the ability to confidently utilize extended aging periods to ensure tenderness, companies supplying beef to retailers should experience fewer claims and account for greater customer satisfaction with beef.  

Providing clear evidence of the effects of postmortem aging on the display life and tenderness of beef retail steaks destined for retail supermarkets is essential for retailers to understand their opportunities for improving the marketability and palatability of their beef products. Therefore, this research was intended to clarify the effects of extend postmortem aging periods on beef in the retail sector to provide a recommended aging time for strip loins and sirloin steaks.  

Methodology 

In order to mimic beef commonly found in retail supermarkets, paired strip loins and top sirloin butts (from both the left and right sides of the carcass) were obtained from USDA Choice carcasses with a marbling score ranging from Small00 to Small50 (n = 15) and USDA Select carcasses with a marbling score ranging from Slight50 to Slight99 (n = 15) at a commercial packing plant. Strip loins and top sirloin butts (both the left and right sides) from an individual animal were fabricated into six, 4- inch portions. Each of the 6 portions was randomly assigned to one of 6 postmortem aging periods (14, 21, 28, 35, 49 or 63 days). For both strip loin and sirloin sections, once the aging period was designated, the sections were stored in a vacuum-sealed bag at 0°C (± 1°C) until their assigned aging period were complete. Then, sections were removed from storage and each section was faced and 3, 1-inch steaks were cut from each section. One steak was immediately designated for Warner- Bratzler shear force (WBSF), while the other two steaks was placed in a traditional PVC overwrapped package and placed in a multi-deck retail display case for 72 hours. During the display period, each steak was evaluated every 8 hours by a minimum of 8 trained panelists for lean color (bright cherry-red to very dark red or brown/green), external fat color (bright, creamy white to dark tan or brown/green), and lean percent discoloration (0 to 100%). Immediately following subjective color analysis, L* a* b* lean color values were measured using a spectrophotometer. Following removal, 1 of the 2 steaks was designated for shear force testing and oxidation analysis (TBARS); the other steak was rated by a trained sensory panel for myofibrillar tenderness, connective tissue amount, juiciness, beef flavor intensity, buttery beef fat flavor, oxidized, sour/acidic, livery/organy, and metallic/bloody. 

Findings 

As steaks were subjected to longer periods of postmortem aging, WBSF values decreased and trained sensory panel tenderness ratings improved. A 72-h display time was shown to significantly reduce (P < 0.0001) WBSF values of strip loin and sirloin steaks. A minimum of 28 d of postmortem aging is required to improve the WBSF values of low Choice and Select strip loin steaks over the same strip loins steaks that have been aged for only 14 d, and a minimum of 35 d of postmortem aging is required to significantly improve sensory tenderness ratings for low Choice and Select strip loin steaks. Sensory panel ratings of off-flavors also supported that aging strip loin steaks for 35 d or more postmortem for retail display and sale is undesirable as the intensity of oxidized and sour/acidic off-flavors significantly increased. This data suggests that strip loin steaks can be aged for 28 d prior to retail display with little effect on display life and the incidence of off-flavors, however, there was no significant tenderness advantage over 14 d aged steaks from low Choice and Select strip loins  

The findings for sirloin steaks indicate that 35 d of postmortem aging are required to achieve an improvement in WBSF over 14 d aged low Choice and Select top sirloin steaks, and trained sensory panel scores indicated that at least 49 d of postmortem aging is required to improve the myofibrillar tenderness of low Choice and Select sirloin steaks. Lean color scores indicated a drastically reduced display life for sirloin steaks aged 35 d or more prior to retail display. Sirloin steaks aged 35 d and more produced undesirable lean color scores in as early as the first 24 h of retail display, which would suggest the need to discount the price of these steaks or even remove them from retail display. Additionally, low Choice and Select top sirloin steaks aged only 14 d and displayed an additional 72 h had relatively intense levels of oxidized and sour/acidic flavors present. With all factors considered for low Choice and Select top sirloins, it is not realistic to conclude that top sirloins can be aged for a long enough period to improve tenderness and maintain a considerable level of display life. Long aging treatments for top sirloins is most well suited for foodservice where display life is a non-issue. 

Implications 

Providing clear evidence of the effects of postmortem aging on the display life and tenderness of beef retail steaks destined for retail supermarkets is essential for retailers to understand their opportunities for improving the marketability and palatability of their beef products. Results of this study will provide guidelines for retail display life which could lead to ensuring that consumers can have confidence that they are buying a consistently high-quality product at retail stores.