Definition of Cold Shortening

When pre-rigor meat is fast chilled below 15°C up to 0°C and 40% muscle shortening takes place, it is known as:

Correct Answer: Cold Shortening

Cold shortening is defined as the phenomenon where pre-rigor meat is rapidly chilled below 15°C to 0°C, causing 40% muscle shortening and extreme toughening of the meat.

Mechanism of Cold Shortening

• At temperatures below 15°C, the sarcoplasmic reticulum (SR) of pre-rigor muscle loses its ability to sequester Ca²⁺.
• Free Ca²⁺ floods the cytoplasm → activates actomyosin ATPase → ATP hydrolysis → muscle contraction.
• Since rigor hasn't completed yet, there is still enough ATP to drive contraction → severe shortening (40%).

Prevention of Cold Shortening

• Electrical stimulation (ES) — most effective; accelerates rigor completion before chilling below 15°C
• Delayed chilling — hold carcass at 15°C for a period before rapid chilling
• Hot boning — bone out meat before rigor and restrain under tension

Compare

• Cold shortening → 40% shortening | pre-rigor + fast chilled below 15°C
• Thaw rigor → 60–80% shortening | pre-rigor + frozen then thawed