Studies in electrical stimulation: Post-mortem decline in nervous response in lambs.

Area of Science:

• Meat Science
• Animal Physiology
• Biochemistry

Background:

• Glycolysis is a key process in post-mortem muscle metabolism, influencing meat quality.
• Electrical stimulation (ES) is used in meat processing to accelerate this process.

Purpose of the Study:

• To investigate the effects of direct muscle versus indirect nerve stimulation on glycolysis in lamb hind leg muscles.
• To determine the influence of stimulation voltage and time post-mortem on these glycolytic responses.

Main Methods:

• Lamb hind leg muscles were subjected to electrical stimulation at varying voltages (12V, 200V) and time points post-mortem (5 min, 30 min).
• Stimulation was applied either indirectly via nerves or directly to the muscles.
• Glycolysis was assessed by measuring the fall in pH (ΔpH) and the rate of pH fall (dpH/dt).

Main Results:

• At 5 min post-mortem, both direct and indirect stimulation at 12V produced similar glycolytic effects.
• At 200V, direct stimulation yielded a greater ΔpH (50%) compared to indirect stimulation (30% less).
• At 30 min post-mortem, indirect stimulation had minimal effect, while direct stimulation at 200V maximized glycolytic responses.

Conclusions:

• Nerve viability diminishes significantly by 30 min post-mortem, reducing the efficacy of indirect electrical stimulation.
• Direct muscle stimulation is a more effective method for accelerating glycolysis, particularly at higher voltages and later post-mortem stages.
• These findings have implications for optimizing electrical stimulation protocols in commercial meat processing.