MODIFICATION OF EARLY-POSTMORTEM MUSCLE PH AND USE OF POSTMORTEM AGING TO IMPROVE BEEF TENDERNESS

This study was conducted to determine whether modification of early-po stmortem muscle pH and(or) control of postmortem aging time could be u sed to improve tenderness of strip loin (longissimus, LM), top sirloin (GM), and top round (SM) steaks. Muscle pH, at 1.5 and 3 h postmortem , was modified using three 60-Hz electrical stimulation (ES) treatment s (240 V, 35 V, or combined use of 240 and 35 V). Vacuum-packaged sect ions of the LM, GM, and SM were aged for 6, 12, 18, or 24 d postmortem . Use of ES increased rate of postmortem muscle pH decline and decreas ed shear force of LM steaks but had no effect on tenderness of GM or S M steaks. Reducing 3-h pH of the LM reduced variability in LM shear fo rce but had little effect on tenderness of GM or SM steaks. However, l ower values for 24-h pH of the LM were associated with increased tende rness of all three cuts. Tenderness of all cuts also improved as lengt h of the postmortem aging period was increased. For LM and SM steaks, the greatest improvements in tenderness were achieved by 12 d; however , tenderness of GM steaks continued to increase up to 24 d postmortem.