Effects of Elevated Temperature Conditioning on Youthful and Mature Beef Carcasses

Single sides from each of 27 steer and 21 cow carcasses were placed in a 0 to 2 C holding cooler 1 hr post-exsanguination. Counterpart sides from each carcass were placed in a 14 to 19 C cooler for 12, 16 or 20 hr (nine steer and seven cow sides per time interval) and then moved to the 0 to 2 C cooler for the remainder of a 48-hr storage period. At 48 hr postmortem, steaks from steer and cow sides held at 14 to 19 C for 20 hr were significantly more tender than those from normally chilled sides. Panel tenderness ratings for steaks removed 7 days postmortem revealed that steaks from sides stored for 12 hr at 14 to 19 C were more tender than those from control sides. Steaks from mature (cow) carcasses exhibited a greater tenderness response to temperature treatments than did steaks from the youthful (steer) carcasses. The sarcomere lengths of myofibrils from cow carcasses were significantly greater for sides held at a higher temperature for 20 hours. Bacterial counts at the termination of the 48-hr storage period were not significantly (P<.05) different between control and treated sides. Pre-rigor storage at elevated temperatures enhanced the visual appearance of subsequent steaks from steer and cow carcasses. In 115 of 120 comparisons (P<.05 in 40 comparisons) steaks from treated sides displayed numerically higher ratings than steaks from control sides for muscle color, consumer acceptability and discoloration during 5 days of retail display.