Electrical stimulation affects metabolic enzyme phosphorylation, protease activation, and meat tenderization in beef

Area of Science:

• Meat Science
• Biochemistry
• Food Technology

Background:

• Electrical stimulation (ES) is used to improve meat quality.
• Understanding the molecular mechanisms of ES-induced tenderization is crucial for optimizing meat processing.

Purpose of the Study:

• To investigate the effects of low-voltage electrical stimulation on sarcoplasmic proteins in bovine Longissimus dorsi (LM) muscle.
• To determine the contribution of these changes to early postmortem meat tenderization.

Main Methods:

• Proteome analysis to assess protein phosphorylation.
• Zymography to measure enzyme activity (μ-calpain).
• Assays for lysosomal enzyme activity (cathepsin B and L).
• Immunohistochemistry and transmission electron microscopy for ultrastructural analysis.
• Measurement of ATP, creatine phosphate, glycogen, pH, and temperature.
• Shear force testing to evaluate meat tenderness.

Main Results:

• ES decreased phosphorylation of key energy metabolic enzymes (creatine kinase, aldolase C-A, β-enolase, pyruvate kinase) at 3 h postmortem.
• ES accelerated μ-calpain activation and the release of lysosomal cathepsin B and L.
• ES induced ultrastructural sarcomere disruption and faster depletion of ATP, creatine phosphate, and glycogen.
• ES accelerated pH decline and promoted a preferred pH/temperature decline mode.
• ES significantly reduced shear force values, indicating enhanced meat tenderization.

Conclusions:

• ES-induced tenderization involves the activation of μ-calpain, altered phosphorylation of sarcoplasmic proteins, and early release of lysosomal enzymes.
• The changes in energy metabolism and protein phosphorylation are linked to accelerated postmortem tenderization in beef.