Meat toughening does not occur when rigor shortening is prevented

Area of Science:

• Meat Science
• Postmortem Muscle Biology
• Food Physics

Background:

• Meat quality, specifically tenderness, is a critical factor for consumers.
• Postmortem changes in muscle, including rigor mortis development, significantly impact meat texture.
• Understanding the mechanisms of meat toughening is essential for improving meat processing and quality.

Purpose of the Study:

• To test the hypothesis that meat toughening during the first 24 hours postmortem is caused by sarcomere shortening during rigor mortis development.
• To investigate the relationship between muscle shortening, sarcomere length, and shear force in lamb longissimus muscle.

Main Methods:

• Lamb longissimus muscles were clamped to prevent shortening during rigor mortis development at -1.1°C.
• Samples were collected at various time points (0-168 hours postmortem) for pH, sarcomere length, and shear force analysis.
• Western blot analysis was used to assess protein degradation (nebulin, vinculin, troponin-T).

Main Results:

• Shear force remained constant from 0 to 24 hours postmortem in clamped (non-shortened) muscles.
• Sarcomere lengths were successfully maintained constant in clamped sections.
• Protein degradation increased with postmortem time, but limited proteolysis alone did not affect shear force.

Conclusions:

• Meat toughening during the initial 24 hours postmortem is primarily caused by sarcomere shortening.
• Preventing muscle shortening effectively mitigates the increase in shear force during rigor development.
• These findings highlight the critical role of muscle shortening in early postmortem meat toughening.