Tenderness Postmortem Factors

Question 1

What are post-mortem factors on tenderness?

Answer 1

1. Cold-shortening
2. Thaw rigor
3. Heat toughening
4. Postmortem aging

Question 2

What temperatures does cold shortening occur?

Answer 2

exposure to temperatures between 0-16°C before rigor mortis

Question 3

What is cold shortening?

Answer 3

Ca released from SR combined with failure of Ca pump results in accumulation of Ca

If combined with high ATP (from a rapid temp decline), then we get severe contraction and lose the I band.

Question 4

What might make a carcass more prone to cold shortening?

Answer 4

less fat cover

Question 5

Who discovered cold shortening?

Answer 5

Locker and Hagyard

Question 6

What has been used to diminish cold shortening in the meat industry?

Answer 6

1. development of chilling systems
2. increased carcass weight and fat thickness
3. application of ES stimulation (accelerates glycolysis and depletes ATP)

Question 7

What is thaw rigor?

Answer 7

shortening when a carcass is frozen pre-rigor and then thawed

Ca crystals cause massive tissue disruption when thawed. Result is 80% shortening and purge

Question 8

What are the conditions for heat shortening?

Answer 8

temperatures above 35°C and a pH of 6

Question 9

What is heat shortening?

Answer 9

Shortening caused by high temperature and rapid pH decline that causes ATP to rapidly deplete, proteolysis to decrease, and protein to denature.

Question 10

What is PSE?

Answer 10

Protein denaturing condition

Question 11

What happens during the resolution of rigor mortis?

Answer 11

Endogenous enzymes (like calpain) degrade structural myofibrillar proteins (at the Z line and I band)

*actin and myosin are not degraded