Conversion of Muscle to Meat

Question 1

How does removal of the blood supply affect the conversion of muscle to meat

Answer 1

• Eliminate oxygen to muscle - anaerobic metabolism
• Eliminate nutrient and waste transport - lactic acid accumulations
• Loss of temperature regulation - lots of heat generation during contraction
• Loss of microbial defenses

Question 2

How does removal of blood affect the nervous system?

Answer 2

• Nerve cells do not have glycogen stores or the ability to produce ATP
• Lose energy supply and fail almost immediately after draining

Question 3

What are the major change in post-mortem muscles?

Answer 3

• Loss of extensibility
• Loss of responsiveness to stimuli
• Isometric tension increases (contraction)
• Temperature increases then decreases
• Muscle pH decline

Question 4

Why does pH decline in post-mortem muscle?

Answer 4

• Production of CO2
• Lactic acid production from anaerobic glycolysis
• No blood supply to get rid of

Question 5

What does pH decline due to water binding capacity?

Answer 5

• Decrease

- Minimum water binding around 5.4

Question 6

How does ATP effect muscle contraction?

Answer 6

• ATP is used to pump calcium back into SR, helping to terminate muscle contraction.
• Also, breaks actomyosin bridges

Question 7

What are “rigor bridges”?

Answer 7

Result from additional changes to actomyosin bridges after ATP fails to arrive and break them for an extended period of time. Even if ATP stores rise, the configuration has changed, and the ATP cannot bind.

Question 8

T/F. Spray chilling helps to replace water lost.

Answer 8

True.

Question 9

What is a disadvantage and advantage to cold water/ice slush dip?

Answer 9

Disadvantage - Huge potential for contamination

Advantage - Inexpensive

Question 10

Describe “dry aging”.

Answer 10

• Carcass or cut is exposed to air
• Surface dehydration, microbial growth
• Improved tenderness, “improved” flavor

Question 11

Describe “wet aging”.

Answer 11

• Cut is in vacuum bag
• No dehydration, limited microbial growth
• Improved tenderness, little change in flavor
• Almost all beef in US is wet aged

Question 12

What metabolites are responsible for aging?

Answer 12

• Calpain/calpastatin - Ca activated factor; Ca dependent protease
• Multi-catalytic protease
• Lysosomal enzymes
• Collagenase

Question 13

Does lower pH increase the activity of lysosomal enzymes?

Answer 13

yes

Question 14

What are the three types of caspase enzymes?

Answer 14

• Initiators - activate other caspases
• Effectors - decrease various proteins in the cell
• Inhibitors - heat-shock proteins

Question 15

What is apoptosis?

Answer 15

Programmed cell death

Question 16

What does caspase 3 activation do?

Answer 16

Releases of myosin and actin