Agriculture Reference
In-Depth Information
mechanically on the return line. In the case of large tur-
keys, retention of the sinews is considered unacceptable.
Instead of cutting off the shanks, an automatic sinew puller
is used, and this draws up to nine of the main sinews.
The carcases are re-hung on the evisceration line after
removal of the feet. This is now done automatically in
most slaughterhouses, using a transfer system available
from several equipment manufacturers. In this case, the
foot cutter and transfer device are combined in one unit.
This lessens the risk of cross-contamination. The empty,
returning, killing line shackles pass through a shackle
washer on their way back to the bird arrival area (Fig. 10.7).
sometimes used. Any feathers remaining on the bird after
plucking, including pin feathers, are removed by hand.
For ducks, wax stripping is used. The ducks are dipped
in a bath of hot wax and then passed through cool water
sprays so that the wax hardens. The hardened wax, with
the feathers attached, is hand stripped. The plucked car-
cases are then spray washed. There is evidence to suggest
that the combination of scalding at 60°C followed by
immersion in molten wax at 87°C to aid final removal of
the feathers has a beneficial effect on the microbiological
status of the finished product.
Defeathering machines are major sites of potential
cross-contamination in primary processing. Rubber
fingers can score the carcase and can also harbour
contamination in the 'cobweb' of tiny cracks which form
when the rubber becomes brittle. In addition, the
spinning action of the plucker heads form aerosols which
can spread contamination. Moreover, since the atmos-
phere inside the machinery is both warm and moist,
microbial growth is encouraged.
Following feather removal, the birds are spray washed,
and at this point, the
whole-bird
post-mortem examina-
tion takes place. It is here that obviously diseased birds,
badly bled and badly bruised carcases, are removed. The
heads of the birds are removed by an automatic head and
windpipe puller. By pulling the heads off rather than cut-
ting them off, the oesophagus and trachea are removed
with the heads. This loosens the crop and lungs, which
assists in their removal by the automatic evisceration
machines.
The birds then pass through an automatic foot cutter.
The severed feet remain on the shackles and are removed
Evisceration
In the EC, the evisceration area must be physically sepa-
rated from the defeathering area.
Chickens are usually suspended from the shackles of
the evisceration line conveyor by engaging the hock
joints two-point suspension. Turkeys are commonly
hung by a 'three-point' suspension which includes the
head as well as the legs. This presents the bird horizon-
tally, making cutting around the vent and evisceration
easier (Fig. 10.8).
Evisceration is mainly carried out mechanically, but
manual evisceration is still practised. On automatic lines,
a cut is made around the vent, a spoon-shaped device is
inserted into the opening, and the viscera are withdrawn.
The viscera may remain attached for inspection, hanging
over the back of the carcase connected by their natural
tissues or hung separately (Fig. 10.9).
Contamination of the carcase surface with
Enterobacteriaceae species may ensue if intestines, etc.
Figure 10.7
Transfer from defeathering into eviscerating line (Reproduced with permission from Stork Poulty Processing, Boxmeer,
The Netherlands).
