Events spanning over the last 4 years have resulted in a shift by processors to increase the use of freezing practices to extend the shelf life of beef products. The shift in practices sometimes results in beef being frozen, thawed, and refrozen, sometimes multiple times before it reaches the end user. The impacts of freezing have been studied a great deal, especially in relation to beef tenderness and the formation of ice crystals within the cellular membrane. In addition, in recent years, the utilization of fabricating subprimals into retail cuts while in a frozen state has become increasingly popular by processors to increase product yields. Furthermore, beef is also subjected to various frozen temperatures post-fabrication, with little known about the impact of different frozen temperatures on the palatability of those steaks. Also, little information exists as to the exact implications of beef undergoing multiple freeze-thaw cycles as well as beef being fabricated in a frozen state. Therefore, our objective was to evaluate the impact of frozen versus thawed fabrication and refreezing at three different temperatures on the palatability and cook traits of beef longissimus lumborum primal and steaks.
Paired beef strip loins (IMPS #180; n = 22) grading USDA Choice were procured from a Midwestern beef processor during grading and fabrication. Following the wet aging period of 21 d, subprimals were frozen for 14 d to initiate the first freezing cycle and randomly assigned to frozen or thawed fabrication. Strip loins designated to be fabricated from a thawed state were thawed for 7 d, while those designated to be fabricated frozen were held in the freezer at 21°C until the day of fabrication. On the day of fabrication, each loin was weighed, 2.54 cm steaks were cut anterior to posterior on a bandsaw, and steaks were weighed following cutting. Each steak was randomly designated to one of three frozen storage temperatures: -12°C, -18°C, or -21°C. Steaks within each frozen storage temperature were assigned to one of three tests: consumer sensory, trained sensory, or Warner-Bratzler shear force and lipid oxidation. Following six months of frozen storage at the respective temperatures, steaks underwent various analyses. For all analysis, steaks were cooked in a Rational® Combi Oven to an internal temperature of 71°C. Warner-Bratzler shear force was performed according to AMSA sensory guidelines. Consumer panelists (N = 160) evaluated samples for tenderness, juiciness, flavor liking, and overall liking on 9-point hedonic scales and a yes/no question about detectable off-flavor. A trained panel was conducted with trained panelists who were asked to rate the initial and sustained juiciness, tenderness, connective tissue amount, beef flavor intensity, and off-flavor intensity on 8-point hedonic scales. In addition, lipid oxidation, cooked internal color, and thaw and cook loss were measured. Finally, statistical analysis of the split-plot design was conducted using the Glimmix Procedure of SAS.
Consumer panel results show no difference (P > 0.05) for tenderness, juiciness, flavor liking, overall liking, and off-flavor detection for either fabrication state or storage temperature. Correspondingly, trained sensory panels found no differences (P > 0.05) in initial juiciness, sustained juiciness, tenderness, connective tissue amount, off-flavor, or beef flavor for either treatment. Furthermore, trained sensory panel results indicated no differences (P > 0.05) in internal cooked color ratings as well as instrumental cooked color. Thawed steaks had lower (P < 0.05) WBSF values than frozen fabricated steaks. Loins and steaks from loins designated to thawing before fabrication had a greater (P < 0.05) percentage of thaw loss when compared to loins and steaks from loins assigned to frozen fabrication. No differences were found (P > 0.05) in steak cook loss regardless of fabrication state or freezing storage temperature. In addition, there were no differences (P > 0.05) in lipid oxidation values.
Fabricating steaks in a frozen state before long-term storage increases product yield at fabrication. Palatability is not impacted following two freeze-thaw cycles and freezing at various temperatures post-fabrication. Therefore, food service purveyors and processors can utilize both frozen and thawed fabrication and refreezing post-fabrication to extend shelf-life without detrimental effects to the end consumer. Furthermore, freezing should be utilized by processors who need to increase product yield during fabrication.