The Influence of Carcass Weight on Beef Primal Temperature, Tenderness, and Palatability

The United States beef industry has experienced increasing hot carcass weights (HCW) and improvements to quality grade the last three decades. Postmortem chilling of beef carcasses is critical to overall product quality. Carcass weight and composition may influence carcass temperatures during postmortem chilling. The objective of this research was to evaluate the effects of HCW and quality grade during postmortem chilling and on product quality. A-maturity carcasses were selected by weight [light = 296–341 kg; middle = 386–432 kg; heavy = 466–523 kg]. A 20 cm data logger was placed into the chuck and round and a 10 cm data logger placed in the loin. Muscles from a subs-sample of USDA Select and low Choice carcasses were collected for further analyses. Ultimate pH and color (Hunter L, a, and b) were measured at the time of steak fabrication. Steaks were aged 5 d for sarcomere length and 5, 10, or 14 d for Warner Bratzler shear force, cook loss, troponin-T and desmin degradation, and consumer sensory analyses. Generally, heavier carcasses with improved quality grade retain heat for an extended period of time. No differences were observed for ultimate pH across weight groups, but ultimate pH was increased from Select to low Choice serratus ventralis muscles. Heavy weight carcasses had higher L, a, and b values compared to lighter carcasses in the serratus ventralis, longissimus lumborum, and semitendinosus muscles (P \u3c 0.05). Shorter sarcomeres were observed in heavy weight semitendinosus muscles (P \u3c 0.05). In the longissimus lumborum, Warner Bratzler shear force was highest in light weight steaks aged 5 d (P \u3c 0.05). By 10 d of aging, no differences were observed between weight groups for tenderness. Protein degradation was also influenced by HCW in all three muscles. In general, sensory attributes of steaks from middle weight carcasses had higher scores overall compared to steaks from light and heavy weight carcasses in all muscles. These data demonstrate HCW can influence temperature decline and overall product quality. Additional research to further explore the impact of HCW and quality grade on temperature decline will help improve chilling systems for the beef industry to continue producing high-quality beef products