PSE & DFD MEAT
Lean Meat Quality
• Poor ante-mortem handling can produce PSE or DFD meat and may influence eating quality.
• PSE affects pigs and DFD occurs in all species.
• PSE-like characteristics, particularly pale color, have been reported in some turkey and chicken meat recently.
The names describe the characteristics of the muscle in comparison with normal meat.
Pale Sof
Exudative
Dark
Firm
Dry
They are defined by the pH value
of the meat
PSE
45 min post mortem of <6
DFD
afer 12–48 hours post mortem of >
6
Dark cutters
• The color of meat is one of the most important criteria consumers use to select meat.
• Meat which is too pale or too dark is discriminated against in preference to normal colored meat
• The large amount of exudate (drip loss or purge) from PSE meat, especially if it collects in the
packaging, also contributes to the undesirable appearance.
Low pH and high temperature causes denaturation of some of
the muscle proteins leading to a reduction in the amount of water they
bind.
Shrinkage of the myofibrillar
components expels the resultant fluid into the extracellular
space
When the muscle is cut the extra fluid exudes to produce the exudate
The large amount of exudate reflects
a poorer water- holding capacity.
The high pH results in relatively little denaturation of the proteins, water is tightly bound and little or no exudate is formed.
Light scattering from the meat surface is probably caused by differences in
the refractive indices of the sarcoplasm and
myofibrils.
The shrinkage of the myofilament lattice increases the amount of
light reflected from the meat.
No shrinkage cause translucent structure that
absorbs rather than reflects light
• PSE meat reduced yield both of fresh meat and of processed products like hams and bacon
• DFD meat has poor processing characteristics with slow or uneven formation of cured meat pigments.
• Flavour development is poor in processed products and flavour is poor in cooked fresh DFD meat
• PSE pork tends to taste dry and have poor texture afer cooking
Glycogen depletion ante mortem characterized by very low levels of carbohydrates in the muscle.
The low levels of carbohydrates present in the meat restrict the growth of lactic acid-producing bacteria
This encourages the growth of bacteria that metabolize amino acids and proteins
These produce unpleasant smelling waste products.
The high pH value of the meat promotes this bacterial growth.
Causes of PSE and DFD meat
• Both PSE and DFD meat are caused by stress experienced live animal at and before slaughter.
PSE
• The problem is greater in stress-susceptible genotypes.
• Poultry and pigs carry one or two copies of the Malignant Hypothermia (Halothane) gene.
• Antemortem stress (short term stress) usually increases the severity of PSE.
• Muscle pH drops very fast, body temp increases causing the meat to be pale in color, sof in texture with exudation of water.
DFD
Chronic stress that can produce DFD meat;
long periods without food (fasting)
fatigue caused by very long transport under poor conditions
fighting that occurs when mixed together
• Caused by a shortage of glycogen at slaughter.
• Without enough glycogen to convert to lactic acid, the muscle pH stays high, closer to 7.0 (living
muscle pH)
• Results in muscle too dark in color, firm in texture, and dry on muscle surface
