The COVID-19 pandemic greatly impacted the beef supply chain. Initially, the food service sectors came to a complete halt, while retail sales ramped up dramatically. Later, harvest capacity dropped due to labor shortages, resulting in less meat for the retail case and greater prices. Recently, research has found that 2.55% of beef at the retail level is discarded due to discoloration: this costs the beef industry $3.73 billion each year.
Suspended aging (-2.2°C) and freezing are potential strategies to help mitigate supply chain issues and reduce food waste. While there is no published research on suspended aging, freezing has been shown to result in a more tender product. The improved tenderness could be due to increased proteolysis. Unfortunately, freezing beef results in greater purge loss or reduced water holding capacity and poorer color. Aging product at different temperatures (4°C, -2.2°C, -20°C, and -78.5°C followed by -20°C) for specific time periods would allow the beef industry to develop a better understanding of how aging temperatures influence purge loss, color, tenderness, and sensory characteristics of beef. Beef packing facilities currently utilize dry ice (-78.5°C) to cool product rapidly. A more rapid freezing method utilizing dry ice should reduce the amount of purge loss during thawing. Additionally, the freezing methods could be attained by the industry with minor modifications of the current supply chain. This would allow for extended periods of frozen storage during trans-Pacific transportation and/or during challenging supply chain times. The objective of the study was to determine the effects of aging subprimals for 35 days at either 2-4°C (control), -2.2°C (suspended fresh), -20°C (blast freezer) or -78.5°C (dry ice; positive control) on fluid loss, shelf-life, tenderness, and sensory characteristics.
Beef Procurement: USDA Choice carcasses were fabricated at 24 h postmortem. At 48 h postmortem, ribeye rolls and top sirloin butts from USDA Choice carcasses (n = 32, each) were purchased from a commercial packing facility and transported (4 hours) to the University of Idaho Vandal Brand Meat Science Laboratory in a refrigerator van, held at 2o C.
Subprimal Preparation: Subprimals were weighed in their original packaging then randomly assigned to one of four postmortem aging treatments, including: 2°C (wet aging; control; C) for 35 days postmortem, -1.5o C (suspended fresh; SF) on day 4 postmortem until 35 days postmortem, -20o C (blast freezing; BF) on day 4 postmortem, frozen for 28 days, and allowed to thaw for 3 days at 2o C, and flash freezing at -78.5o C (dry ice; positive control; FF) on day 4 postmortem, frozen storage for 28 days at -20o C, allowed to thaw for 3 days at 2o C. Subprimals assigned to FF were placed in plastic lugs and packed with dry ice to the rim of the lug, prior to being stored at -20°C. After 4 hours of storage at -20o C, 1.4 kg of dry ice was added to each lug. One lug was used for two subprimals, which were stored and frozen together, but not touching. Following the 35-day aging period, subprimal percentage of fluid loss was calculated.
Steak Preparation and analysis: On day 35 postmortem, the longissimus thoracis (LT) and gluteus medius (GM) were removed from their respective subprimals. From each muscle, five steaks (2.54 cm) were cut; one was assigned to color shelf-life, one to lipid oxidation and microbial analysis, one to Warner-Bratzler Shear Force (WBSF), and two steaks were assigned to sensory analysis. Steaks were randomly assigned to an analysis parameter based on location in the subprimal.
The results of the current study demonstrate that both refrigeration and frozen storage of beef subprimals contribute to improvement of various shelf-life and sensory attributes. While steaks cut from refrigerated subprimals maintained a redder appearance, steaks cut from frozen subprimals exhibited lower levels of lipid oxidation throughout retail display.
Freezing treatments could be beneficial for both food service and export trade due to the mitigation of lipid oxidation while refrigeration treatments will lead to greater consumer appeal at the retail level, decreasing losses to the industry due to discoloration.
ARMS#120525-16