Pos Mortem Changes

8/9/2019 Pos Mortem Changes

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POST MORTEMCHANGESy

Microscopic anatomy of Skeletal Muscley The Sliding Filament Theoryy Rigor Mortis


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MUSCLE STRUCTURE


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MUSCLE STRUCTURE


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MUSCLE STRUCTURE


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PALATABILITYy Of the six meat palatability

factors (tenderness, juiciness,flavor, aroma, color, texture),tenderness is generally consideredthe most important palatability

factor by the consumer.


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D IFFERENT MUSCLESDifferent muscles in the meat animal have differentfunctions.

y S ome muscles are defined as muscles of locomotion .These muscles are used to move the animal and as a

result of this function, they are less tender.y The other muscles in the meat animal are called

muscles of attachment . They do very little work and asa result of less work they are more tender.

y They are often called middle meats and they sell for ahigher price because of their tenderness.

y Muscles found in the loin and rib are examples of muscles of attachment.


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M uscles of attachment

M ajor muscles of locomotion


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A nimal slaughtered

Exsanguination

Blood pressure drops(In an attempt to maintain the blood pressure and ensure

blood supply to vital organs)

i) Heart pumping increasesii)peripheral vasoconstriction

Results in stoppage of nutrient supply to muscle and removalof waste products loss of oxygen supply to muscle.

Temperatureof carcass rises due to failure of temperaturecontrol mechanism.

Myoglobin stores little oxygen which is sufficient forshort period as a result stored oxygen is depleted.


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.

The above sets in anaerobic metabolismleading to production of lactic acid.

The energy so produced is less and is only sufficientto maintain structural integrity and temperature.

Lactic acid produced as an end product

of anaerobic metabolism can not be removedand is thus stored in muscles

The above leads to fall in pH( the final pH would depend on amount of glycogen in the muscle at

the time of exsanguination )

A s all homeostatic mechanisms have failed bythis stage means that all defense mechanisms including

those which protect a live animal against microorganisms are lost .A s a result muscle becomes susceptible to microbial invasions


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y

A fter death, the muscle fibers contract as thelactic acid content increases in the muscle.y This is known as rigor mortis and this

occurrence causes muscle to become less

tender especially in young cattle.y Rigor is complete after about 48 hours post-

mortem. The lactic acid is produced afterdeath from glucose which is stored in muscle.

y This is called post-mortem glycolysis andoccurs without oxygen. Rigor causes themuscle to shorten which results in muscletoughening.


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RIGOR MORTISy Muscle continues to contract and relax after

deathy Without oxygen, lactic acid builds upy Energy production stopsy Muscle filaments permanently lock togethery Muscle becomes stiff y If filaments lock in a relaxed state, muscle is

tender

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Pos Mortem Changes