MEAT Flashcards
(31 cards)
Process of slaughtering
- muscle continues using energy ATP until all O2 is consumed
- aerobic metabolism stops
- anaerobiv metabolism: glycogen–> ATP + lactic acid
- breakdown of sacroplasmic reticulum at low pH leaks Ca2+
- onset of rigor mortis
phenomenon related to post rigor mishandling
- cold-shortening
- thaw rigor
- heat rigor
POST-RIGOR & MEAT TENDERIZATION
-non-enzymatic weakening of actomyosin
-enzymatic proteolysis of myofibrillar protein structure
-weakening of stromal proteins (perimesium and endomesium)
FACTORS AFFECTING & ASSESSMENT METHODS
- WHC
- MEAT COMPOSITION
- MEAT COLOR
- MEAT TEXTURE
Cold shortening
Substantial contraction occurs
when meat subjected to drastic
temperaure drop while the
reserve of ATP is still high.
Thaw rigor
Severe form of
contraction occur when
meat frozen prior to
onset of rigor
Heat rigor
Toughening of meat due to
slow cooling and fast pH
decline
POST-RIGOR & MEAT TENDERIZATION
non-enzymatic weakening of actomyosin
Enzymatic proteolysis of myofibrillar protein structure
Weakening of stromal proteins (perimesium & endomesium)
At isoelectric point,
attraction of structures
also reduces space & shrink the myofibri
Minimum WHC of meat at pH 5.3
(isoelectric point (pI) of myosin, largest
fraction of protein) & actomyosin (pI=5),
number of positively and negatively
charged groups of the myofibrillar
proteins is equal.
Factors affecting tenderness of meat:
Age of animal- amount of connective tissue component
Muscle structure: least used muscles (loin, round) > (chuck)
Cold shortening
Proteolytic degradation / Aging
Mechanical tenderization
Tenderness of meat is composed of:
Mechanical (hardness, cohesiveness, elasticity)
Particulate (grittiness and fibrousness),
Chemical components ( juiciness and oiliness)
dark firm dry meat-glycogen store is
less
dfd meat- ultimate pH is
high (>6.3)
dfd meat- most surfaced appear dry due to
high WHC, MUSCLE PROTEINS RETAIN MOST BOUND WATER AND REMAIN SWOLLEN
DFD MEAT- animal exposed to
long term presalughter stress
PSE -Glycogen lvel
higher than normal
PSE- phu drop very quickly when carcass is still hot, causing
protein denaturation
PSE - meat surfaces are watery and loght coloured due to
low WHC
Physiological changes: Factors that promote quality deterioration of meat
Water → ice crystals cause volume expansion (9%) distorts the structure of meat cell
Dehydration of protein molecules
Increase in solute concentration in the muscle tissues
Foods with high lipid content exhibit less expansion
because lipids contract when crystallize.
“Freezer burn”
Fuzzy, greyish-white spot / brown stain on meat
what cause recrystallization of
ice & moisture migration out of meat.
temperature fluctuations
Increase in size of ice crystals expansion will?
destroy fibular muscle
freezer burn will accelerate
oxidative rancidity, proteins denaturation,
toughening
