Harvesting Flashcards
What does muscle pH gradually decline to post-mortem?
5.5 from 7.0.
What are the 5 reasons that muscle pH experiences the fluctuation it does post-mortem?
- Glycogen depletion.
- Oxygen depletion leading to anaerobic respiration as a result of exsanguination.
- Lactic acid build-up.
- Inactivation of some glycolysis enzymes.
What other energy source is depleted post-mortem?
Creatine phosphate.
What is rigor mortis a result of?
Myosin heads tightly bond actin and muscle filaments will no longer slide due to no calcium being present.
What are the 2 ways that rigor mortis is overcome naturally?
- Z-Line breaking.
- Partial degradation of troponin.
What is the primary candidate for protein degradation?
Calpains or calcium-activated proteins.
What substance inhibits calpains?
Calpastatin.
How long are hogs held off of feed before slaughter?
14-16 hours.
Why are hogs held off of feed before slaughter?
- To assure bleeding completeness.
- Ease of evisceration.
- Reduction of carbohydrates available to become lactic acid.
What characteristics does meat with less lactic acid have?
- Higher ultimate pH.
- More desirable color.
- Increased water-holding capacity.
How is dressing percentage calculated?
(Hot carcass weight/live carcass weight)*100.
What is the average dressing percentage of a hog?
70%.
Approximately how much weight does a hog carcass lose during chilling due to moisture evaporation?
2%.
Hogs with what carcass traits tend to dress higher?
- Fatter.
- Heavier muscled.
- Heavier hogs.
What carcass trait in hogs results in dressing lower?
Excessive fill.
What are the 3 acceptable stunning methods for use in hogs?
- Electric.
- Mechanical.
- Chemical (CO2).
What must the electrical stunning method induce in hogs?
Cardiac arrest.
*Reduced blood splashes in the muscles.
What are the 3 methods of mechanical stunning used in hogs?
- Mushroom compression bolt.
- Penetrating compression bolt.
- .22 caliber rifle.
What does the use of CO2 reduce the incidence of?
- Blood splashing.
- Shoulder and backbone fractures.
- PSE.
What is exsanguination?
The severing of the carotid arteries and jugular veins in a way that leaves a hole no wider than the knife blade.
When is exsanguination done?
Immediately after stunning.
Why is the blood from exsanguination caught?
If it reaches the sewers, it will create a biological oxygen debt (BOD) that will retard sewage drainage.
Why is scalding done?
To loosen the hair on the hog carcass for easier removal.
What temperature should the water be during scalding?
143 F.