Meat Stage in Which Cold Shortening and Thaw Rigor Occur

Cold shortening & Thaw rigor commonly occur in:

Correct Answer: Pre-rigor Meat

Both cold shortening and thaw rigor occur in pre-rigor meat — meat that is chilled or frozen before rigor mortis has completed.

Why Pre-rigor Meat is Vulnerable

• In pre-rigor meat, muscle ATP levels are still sufficient to maintain some excitability.
• Cold temperatures below 15°C trigger uncontrolled calcium release from the sarcoplasmic reticulum → actomyosin bond formation → muscle contraction/shortening.

Cold Shortening

• Occurs when pre-rigor meat is rapidly chilled below 15°C (down to 0°C).
• Results in 40% muscle shortening (severe toughening of meat).
• Prevented by: electrical stimulation, chilling to 15°C and holding, 'hot boning'

Thaw Rigor

• Occurs when pre-rigor meat is frozen, then thawed.
• On thawing, a severe rigor mortis occurs rapidly → 60–80% muscle shortening (most severe form of muscle toughening in meat).
• Much more severe than cold shortening.

Post-rigor Meat

Once rigor has completed and resolved through proteolytic enzymes (conditioning/ageing), the meat is tenderised — cold shortening and thaw rigor cannot occur in post-rigor meat.