Test 2 Continued Flashcards
Do the functions of muscle stop at death?
No
What can still occur postmortem?
Metabolism and contraction.
During and after slaughter, the body is attempting to maintain what?
Homeostasis
Homeostasis is maintained by these, which do not exist in a postmortem system.
Nervous and endocrine systems.
Conversion time for chickens, pigs and cattle?
Chickens: 30 mins
Pigs: 6 hours
Cattle: 12-24 hours
What are the steps of conversion?
Immobilization, exsanguination, and shift in metabolism.
What is it when an animal is unconscious and it’s nervous system is disrupted?
Immobilization
What are the three types of stunning?
Electric bolt, chemical (CO2), and mechanical.
What is the removal of blood, which severely compromises homeostasis and decreases blood pressure?
Exsanguination
Metabolism shifts from aerobic to…
Anaerobic
Loss of circulation causes loss of what?
Temperature control.
What is the peak temperature in carcasses after slaughter?
107-109 F
At high temperature proteins become what?
Denatured
Stiffness of death is what?
Rigor mortis.
Rigor mortis causes the formation of what?
Permanent actin and myosin bonds.
What are the steps of rigor mortis?
Delay, onset, completion, and resolution.
What is delay?
Muscle at original length and flexibility; calcium can be held within the SR.
What is onset?
Muscle starts to lose flexibility; sarcomere starts to shorten and tension increases, which causes toughness; contraction occurs due to presence of ATP and leakage of calcium from SR.
What is completion?
Muscle is at max tension, actin/myosin cross bridges are fully formed, no ATP or capacity for protection of ATP exist within the muscle.
What is resolution?
Slight decrease in tension caused by protein degradation.
Shift in metabolism from aerobic to anaerobic causes an increase in production of what?
Lactic acid
What is the normal pH of muscle?
7.2
What is the normal pH of meat?
5.3-5.8
What directly influences meat quality and what do they entail?
Rate: how fast pH drops.
Extent: how low pH gets.
What influences rigor?
Depletion of ATP.
What is pH decline?
Glycogen to glucose to lactic acid and ATP.
What is PSE?
Rapid decline of pH postmortem due to acute stress antemortem, which causes a buildup of lactic acid prior to death.
In PSE the acidic conditions coupled with increased temperature causes protein denaturation, which leads to what?
Loss of WHC.
What is the pale appearance caused by?
Free water being purged from the muscle and myoglobin being lost.
What makes meat soft?
Lack of water.
What causes the meat to be excavated?
Free water of surface of product and leaks/drips water.
What has a very slow ph decline and high ultimate ph?
Dark, firm, dry.
What is the ultimate pH in DFD?
6.2-6.4
What causes DFD?
Chronic antemortem stress.
Chronic stress leads to a lack of this in postmortem muscle, meaning very little atp and lactic acid generation.
Glycogen
What causes the dark appearance in meat?
Retained water due to high pH and retained myoglobin.
What causes firmness in meat?
Retained water.
What causes dryness in meat?
No free water leaves so no water appears on the surface.
What happens 24 hours postmortem?
There is no ATP, completion of rigor, pH decline has stopped, and temperature decline should be complete.
What is electrical stunning?
