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Bioscience Methods 2012, Vol.3, No.7, 43
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glycogen level was related to more acid meat as low
pH 24 post mortem is related to PSE (pale, soft,
exudative) meat. According to Kotula and Wang (1994)
glycogen levels decrease as fasting time increases as
they found that 0 hour and 36 hours of fasting resulted
in glycogen values at 0 hour post mortem of 7 mg/g
and 3.5 mg/g respectively.
Romo (2001) found that broiler not submitted to
pre-slaughter fasting presented has a higher incidence
of PSE meat (pH<5.7 up to 15 minutes) as compared
to those submitted to fast, with a 24% (12 birds)
incidence in Ross broilers and 13.33% (eight birds) in
Cobb broilers. Castro (2006) also asserted that higher
PSE frequency relates to very short fasting periods, as
there is high glycogen availability in the muscle.
Therefore, fast relate to meat pH and influences the
incidence of PSE in chicken meat (Komiyama et al.,
2008).
1 Water-Holding Capacity (WHC)
Muscles consist of 65%~80% of water that exists in
free, immobilized, or bound form. A product’s
water-holding capacity is primarily determined
through exposing the product to external forces such
as cutting, heating, grinding, or pressing (Hedrick et
al., 1994). Since water is a polar molecule, it can
become associated with electrically charged reactive
groups on the muscle proteins, resulting in a strong
attraction and immobilization known as bound water.
Bound waters will continuously attract other water
molecules, resulting in immobilized water. Immobilize
water has less order and thus a lower attraction to the
reactive groups. Only surface tension holds free
waters that can be easily removed with little physical
force such as the shrinking of myofibrils during the
development of rigor mortis. Rapid pH decline in a
high temperature carcass results in denaturant and
shrinking of myosin, and reducing filament spacing
(Offer, 1991). Consequently, water is expelled from
the cells and lost as purge or drip loss. Products
processed from PSE meat not only have been
lowering water binding capacity (lower yields), but
also exhibit the reduced cohesiveness (Solomon et al.,
1998; McCurdy et al., 1998; Scott, 2005).
2 Harvesting and Transportation
There is evidencing in the literature that catching often
results in injury, especially when many birds are
caught with maximum haste by the catching team.
(Leandro et al., 2001) identified and quantified losses
when comparing both manual and mechanized
catching (16.5% to 7% respectively). The authors
found bruising in thighs, legs, and breasts of up to
25% of the harvested birds due to handling, catching,
transportation, and unloading at the processing plant.
However, most damage in the carcass was found
during catching in the breast (11%), thighs (33%), and
wings (38%). Hip dislocation occurs when birds are
caught in the broiler sheds and loaded into the
transportation crates. Catchers usually hold several
birds by one leg in each worker hand. If one or more
birds start flapping their wings, their hip twists, the
femur detaches, and a subcutaneous hemorrhagic are
produced, killing the bird. Dead birds with dislocated
hip often have blood in the mouth. Sometimes, too
much haste caused this damage by the catchers
(Baracho et al., 2006).
3 Results
The results show that the mean of withdrawal period
was 13 hours, and we found bruising in thighs, legs,
and breasts of up to 2% of the harvested birds due to
handling, catching and transportation (Table 1).
The pH of the samples during 24 h postmortem
showed that 80% of the samples considered as normal
meat (pH>5.80) and 20% of the samples considered as
PSE meat (pH≤5.8).
The results show that the mean of water holding
capacity were 62% and (WHC) of 20% of samples
were less than 60% and these samples considered as
PSE meat (Kissel et al., 2009).
The emulsion stability (ES) value of PSE meat (10.5%)
was significantly higher than in normal meat
(7.6%~7.8%~7.7%~7.8%). The ES value was less
when added starch and isolated soy protein, which
suggests that soy protein acts synergistically as an
emulsifier. This improve the final product’s ES, as
previously observed by Wang et al (2000), Kissel et al
(2009).
The mean of the drip loss of all samples were 5.5%
whereas 20% of samples were more than 6% and
these samples considered as PSE meat Jensen et al
(Jensen et al., 1998).