Agriculture Reference
In-Depth Information
prior to consumption and those parts and material
where more significant processing is required, com-
monly referred to as edible co-product, as follows:
Edible output - minimal processing: carcase meat,
mechanically separated meat (MSM), blood and red
offal, for example, liver and kidney
Edible co-product: treated stomachs, bladders and
intestines, collagen and gelatine from hides and bones,
rendered fats, etc.
Table 8.4
Average breakdown of 450 kg steer and 21 kg lamb
Steer %
Lamb %
Carcase and other edible output
62-64
62-64
Edible fat
3-4
5-6
Blood
3-4
3.5-4
Animal by-product
8-10
6-7
Stomach and intestine contents
8
5.5
Hide (skin and fleece in lamb)
7
15
The non-edible output of the slaughterhouse is the
animal by-products. However, animal by-products are
not simply those parts which cannot be eaten, like the
SRM, content of the gastrointestinal tract and material
declared unfit for human consumption. Animal by-
product includes that material which could be used for
human consumption but which for commercial reasons
the food business operator has decided will not be sold
for human consumption. In other words,
animal by-
products are all those parts that are not intended for
human consumption.
It should be noted that once the
decision has been taken that the material which could
have been used for human consumption is an animal by-
product, it cannot later return to the human food chain.
It is essential that controls are in place to ensure that,
in particular, products categorised as animal by-prod-
ucts cannot be later be reintroduced to the human food
chain. The practice of diverting animal by-product to
the food chain has led to serious incidences of fraud and
public health concern in the past with not only unfit
meat being upgraded from animal by-product to meat
or edible product but also animal by-products destined
for pet food such as chicken feet, pig stomachs and tripe.
The yield from meat animals during the slaughter
process of non-edible outputs ranges from 20 to 30% of
the live weight for beef, pork and lamb and from 5 to 6%
of the live weight of chickens.
The non-muscle parts of animals, owing to their
higher glycogen content and lesser fat covering, are more
perishable than the carcase meat, and they must be
chilled quickly to lower temperatures than the muscle to
control the microbiological load. They should be kept at
a temperature of not more than 3°C. Freezing does not
significantly decrease the bacterial numbers in edible
products or co-products, but a temperature of −12°C will
arrest all microbial growth. Vacuum packaging will also
increase the shelf life, which in some cases can be
doubled using this technique. Some of these products
can also be cured, smoked, pickled and/or canned. All
material intended for human consumption must come
from animals which have passed both ante-mortem
and post-mortem inspection and have been harvested
and handled hygienically and stored appropriately.
The
pet food industry
utilises materials which are not
acceptable for human consumption, that is, those which,
although edible, are not in demand from the consumer
and so have a low monetary value, such as cow's liver.
Material that is considered unfit for human consump-
tion but which does not present a risk to animal or
human health can be used for pet food, for example,
parasitic livers. The handling and storage should be
hygienic, but chilling is not essential for 24 hours if the
material is to be processed. However, there must be
complete separation from material for human consump-
tion as some of the pet food products will not have been
presented for veterinary post-mortem inspection, for
example, chickens' feet.
The use of specialised glands for
pharmaceutical
purposes, although still carried out, has decreased owing
to the biotechnical manufacture of medicines, which
allows for a more consistent product (Table 8.4).
Treatment of edible co-products
Fats
With the exception of the hide, the most valuable
output of the abattoir is the fat trimmed from the intes-
tines (except mesentery which is SRM), kidney area,
channel and other internal organs of cattle. Fats are
graded as follows: 1 refers to edible fat and 2-6 inedible
fat. The grades are dependent on free fatty acid (FFA)
content and colour. Caul (omentum and its contained
fat droplets) and kidney fat are rendered to produce
premier jus, which is separated into oleo oil and oleo
stearin (suet). Dripping is made from caul, kidney and
body fat. Grades 2-6 are used in animal feeds, soaps
(mainly 2-4) and the chemical industry (predominately
6). The latter uses them in such diverse products as
toothpaste, lubricating oils (where they can be used
in two-stroke marine biodegradable fuel), plastic, cot-
ton and liquid washing detergents. More traditionally
they have been used in the dressing of leather, and pro-
duction of commercial glycerine, which itself is used
in medicinal preparations, nitroglycerine, gunpowder,
cordite and dynamite.
