PRERIGOR CARCASS MUSCLE STRETCHING EFFECTS ON TENDERNESS OF GRAIN-FEDBEEF UNDER COMMERCIAL CONDITIONS

A prerigor cut was made through the 12th thoracic vertebrae and anothe r skeletal cut through the ischium on the pelvic bone of one side of 1 6 USDA Choice and 9 USDA Select beef carcasses (TC), while the compani on sides served as controls (C) under industry conditions. TC lowered CIE a values and resulted in longer sarcomeres in the longissimus musc le (LM). Compared to the C samples, the LM from TC USDA Choice carcass es were rated 28% higher (more tender) in overall tenderness and treat ed USDA Select carcasses were 18% higher. Also, variation in tendernes s of the LM among animals was reduced by the TC Process. For Gluteus m edius and Rectus femoris (RF), the TC samples were also more tender.