2009_Book_FoodChemistry

592 12 Meat
Fig. 12.28. Swelling of meat as affected by ATP addition.
Beef muscle homogenate; pH 6.8; — 2 h postmortem,
−−− 4 days post-mortem (according to
Hamm, 1972)
the live weight) can be processed into plasma
(60–70%) and blood concentrate (30–40%,
hemoglobin). The animal bodies are then passed
to skinning machines via scalding vats and
unhairing machines. Subsequently, the animals
are disemboweled, the red organs and the stomach/intestine
package are separated for further
processing. The animals sides are passed through
a shock tunnel (air temperature −4 to−10 ◦ C,
1–2 h). They are stored in the cold until they are
cut up on conveyor belts. During processing,
accumulating fat is fed to the grease boiler. All
discarded materials and bones are processed
into meat and bone meal in carcass processing
plants. The waste water is treated using specific
processes.
is still warm and due to the presence of high
concentrations of ATP. After the onset of rigor
mortis ATP breaks down, the rigidity of the
tissue increases and the water holding capacity
starts to decrease (Fig. 12.27). Addition of ATP
to muscle tissue homogenates prior to the onset
of rigor mortis brings about a rise in tissue
swelling (Fig. 12.28). Addition of low levels of
ATP (to about 1 ×10 −3 molar) during post-rigor
brings about tissue contraction or shrinkage,
while higher levels of ATP cause tissue swelling
(Fig. 12.28). This influence on swelling, however,
is of short duration since, as ATP breaks down,
contraction and shrinkage take place. Nevertheless,
these studies amply illustrate the softening
effect of ATP and, as already mentioned, the ability
of ATP to dissociate actinmyosin complexes
(cf. 12.3.2.1.5 and 12.3.2.1.6). Thus, because of
high ATP levels and high pH, the slaughtered
muscle which is still warm has a high water
holding capacity, whereas post-rigor meat, with
low ATP and low pH, has a low water holding
capacity.
12.6.1 Kinds of Meat, By-Products
12.6.1.1 Beef
The most important categories are:
• Young bull meat from full-grown animals (18–
22 months, live weight >300 kg): fine fibered,
well marbled.
• Cow meat from animals (>2 years) which
have already calved: medium red to brown
red, moderately fine to coarse fibered, yellow
fat, marbled.
• Heifer meat from young, full-grown female
animals (15 to 24 months) which have not
calved: red, fine fibered, white fat.
The meat of bulls (>5 years) and oxen (2–3
years) is of little economic importance. The
average amount of waste from slaughterhouse
oxen is 40–55%; that from cows, 42–66%. Beef
carcasses are hung for 4–8 days before being cut
up for soup meat, and 10–14 days for roasts or
steaks.
12.6 Kinds of Meat, Storage,
Processing
Modern slaughterhouses are higly automated.
After the delivered animals are stunned either
electrically, or by using a bolt apparatus, or
with CO 2 , they are bled. The blood (3–4% of
12.6.1.2 Veal
Meat from young cattle (ca. 4 months) with
a body weight up to 150 kg when slaughtered.
Color: pale red. The meat aroma is weaker than
that of beef. The meat is hung for 8 days before
use.