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Today’s production systems are producing larger and fatter cattle that create size and fatness carcass variations. In addition, modern industry practices that are applied to solve different issues are working against one another in relation to color and tenderness development. The major issue related to temperature during carcass chilling with the intention to counteract the effect of hot carcass washes and electrical stimulation that result in a variety of biochemical reactions that affect color performance and tougher beef. The objective of this study was to evaluate the effects of high to low temperatures in the early postmortem period on the tenderness and color development of beef.
Three muscles: 1) semimembranosus (SM); 2) longissimus lumborum (LL); 3) psoas major (PM), from each side (n = 16) were collected pre-rigor from each carcass. After collection each muscle (n=48) was divided into two different sections (N= 96), sliced at its center part of the whole muscle. Each section was randomly assigned to different temperature treatments established at 30, 35, 40 and 45 °C applying an immersion water bath for 30 minutes and immediately chilled after temperature treatment application. Temperature decline and pH data was collected during the chilling process. Samples were vacuum packaged and wet-aged for 14 days at 2 to 4 °C. 1-inch steaks were fabricated and randomly assigned for shear force, objective and subjective color display, and posterior biochemical analyses.
The interaction between treatment effect and timepoint observed influenced the pH decline of PM and SM (P < 0.1). LL muscle was not affected by treatment and time interaction (P = 0.34). The interaction among temperature and time was not significant (P > 0.1). Interaction between temperature and treatment main effects was not significant for all the objective and subjective traits evaluated in retail case display (P > 0.80). PM muscle, 45 °C possessed the highest L* (P < 0.001) and a * value (P < 0.05) of all the treatments over all the retail display panels. Color panelists panelist perceived the 45 °C treatment to have the least redness of all the treatments. Myoglobin and NADH measurements were not affected significantly by treatment main effect (P > 0.1). Mitochondrial quantification was affected by temperature treatment effect (P < 0.1), the 45 °C treatment had the highest amount, and a greater quantification number than the 35 °C treatment. Measures of shear force log transformed values were not influenced by temperature treatment effect (P > 0.19) for all the muscles analyzed. In agreement, sarcomere length (µm) presented no differences for treatment effect (P < 0.1). The temperature treatments used in this study had an interaction effect with time in the biochemical pH decline mechanism of the SM and PM muscles.
Subjecting beef muscles (semimembranosus, longissimus lumborum, and psoas major) to a 10 range in temperature (35 - 45 C) immediately postmortem affected pH decline and chilling rates of the muscles, but did not change to meaningful differences in color development or notable changes in sarcomere length or measures of tenderness. Additionally, this particular range in temperature treatments did not significantly alter the interaction of O2 with myoglobin during the bloom period. Moreover, oxidation-reduction potential (NADH+) and mitochondrial concentration were not changed as a result of temperature treatments.