Post-mortem electrical stimulation and high temperature ageing of hot-deboned beef

The effects of electrical stimulation (80-100 V, 15 pps) of hot-deboned, bovine Longissimus dorsi muscles, followed by ageing at 30° or 40°Cfor 5, 7 or 10 h, on the solubility of sarcoplasmic and myofibrillar proteins, soluble non-protein nitrogen, and on the water-holding capacity, colour, tenderness and microbiological status of the meat, was assessed. Comparisons were made with the same traits measured on non-stimulated controls (average muscle temperature, 5°C), which were cold-deboned post rigor, and with hot-deboned, electrically stimulated muscles, subsequently held at 2°C. For each treatment and its corresponding control, six muscles each were studied. Such electrical stimulation produced a typical acceleration of pH fall post mortem and enhanced ageing changes at both 30°C and 40°C. It significantly increased tenderness over non-stimulated, cold-deboned controls. The higher temperature of ageing, however, was significantly associated with adverse colour development, loss of water-holding capacity and increased microbial growth. Electrical stimulation alone would not obviate the need for immediate refrigeration in hot-deboning operations with ambient temperatures of ∼ 40°C.