Low voltage electrical stimulation of lamb: Its effect on muscle pH and tenderness

The influence of various characteristics of low voltage electrical stimulation on the pH fall in muscles of lamb carcasses and the tenderness of the muscles from the frozen carcasses has been studied. The stunning method, postmortem delay before stimulation, stimulation period, and some electrical characteristics affected the magnitude of the pH drop during stimulation and the time for muscle pH to fall below 6.0. In general, stimulating earlier, longer, or with higher currents increased the magnitude of ΔpH. The shape of the stimulating pulse had no effect but the polarity of the stimulating wave form affected the result. Making the head positive with respect to the rest of the body ensured the maximum effect for the stimulating conditions. The tenderness of muscles from stimulated carcasses was dependent not only on stimulating conditions but also on the post‐stimulation delay before freezer entry. With a 120 s stimulation period applied within 5 min of slaughter, a 3 h delay was necessary before freezing to avoid any toughening of the important muscles. If a carcass stimulated with low voltage currents is restimulated 30 min later with high voltage, the time for muscle pH to reach 6.0 is reduced. Freezing can then be carried out earlier than otherwise without causing toughening.