Agriculture Reference
In-Depth Information
financial investment in demonstrating equivalence.
However, it is claimed that chemical sterilisation systems
can be more cost-effective in the long term mainly on
account of the reduction in energy costs. A somewhat
unforeseen advantage to the chemical alternative is that
knife blades are not dulled by the hot water of the steri-
liser, remain sharp for longer and so require less steeling
to keep their edge.
Table 8.3
Minimum water temperatures for knife sanitation,
according to the minimum observed immersion time of knives
during routine operation
Observed
minimum
immersion time
(seconds)
Immersion
temperature
without pre-rinsing
(°C)
Immersion temperature
following a pre-rinse in
40°C running water (°C)
1
82
75
Hygienic use of the scabbard
Scabbards of the closed type can usually be considered to
be unhygienic and a source of contamination to a steri-
lised knife. The newer open stainless steel scabbard is a
considerable improvement.
A scabbard is necessary, for health and safety reasons,
for the transportation of knives to the workstation. Once at
the workstation, all knives should be unloaded into the
steriliser from which they are used for the rest of the work-
ing day. The only major exception to this rule on the
slaughter line is the operative who removes the head from
the bovine. On most slaughter lines, he must carry the
head from the point of removal to the washing cabinet,
where the head is hung, trimmed and washed inside and
out with a high-pressure spray. It would be unsafe for him
or her to do so with the head in one hand and the knife in
the other.
5
80
70
10
70
70
20 or more
65
60
A study by Goulter, Dykes and Small (2008) estab-
lished the importance of pre-rinsing of knives prior to
immersion in the steriliser. They also established that at
a range of temperatures, increasing the immersion time
from 1 to 5 seconds gave a significant increase in bacte-
rial reduction. FSA suggested combination of tempera-
ture and time for effective knife sterilisation, with and
without rinsing as given in Table 8.3.
In order that knives in particular spend sufficient time
in the water at 82°C, or alternative temperatures, it is
necessary for each operative to have several knives. This
modus operandi is known rather grandly as the
multiple
knife technique
. When the operative arrives at the work-
station to commence work, he or she places a number of
clean knives in the steriliser. Each time a knife becomes
contaminated, it is washed and placed in the steriliser
and another knife is selected. The knives are used serially
so that each has spent the maximum possible period in
the steriliser.
This technique is suitable for knives. However, for
larger equipment like hock cutters, it may be necessary on
some lines for equipment to be doubled up so that each
item can spend sufficient time being decontaminated.
Operator's wishing to use alternative systems of steri-
lisation to water at 82°C must be able to demonstrate that
the alternative systems are indeed equivalent or better. In
addition to efficacy, alternative systems must not intro-
duce any new hazard to the process. Suggested alterna-
tives include chemical-based systems and use of
ultraviolet light. Given the amount of gross contamina-
tion that any system on the slaughter line will have to
deal with, there has been considerable scepticism about
viable alternatives. Any trial to demonstrate equivalence
must do so under commercial conditions and as such be
tailored to each individual slaughter line. The trials must
be run in parallel with use of water at 82°C so that the
resultant meat has been produced in accordance with
European law. Results from chemical trials conducted
to date remain commercial in confidence due to the
Hygienic use of the steel
The steel, which is used to keep the knife sharp, is a source
of contamination frequently overlooked in daily opera-
tions. A traditional bar steel which is hanging from the
user's belt, dangling either inside or against the outside of
a wellington boot, cannot be considered as a suitably
hygienic surface against which to rub a knife which has
just been removed from a steriliser. The cleanliness of the
steel, and its storage when not in use, are therefore very
important. On arrival at the workstation, the steel should
be removed from the belt or scabbard and sterilised. It is
unreasonable to expect the steel to be stored throughout
the day in the steriliser, since most operatives believe that
this practice destroys the effectiveness of the steel. It
should therefore be stored hanging freely from a hook at
the workstation where it will remain effectively sterile,
provided only sterilised knives are used on it. The steel
should not be stored in the wash-hand basin, where it will
be contaminated from waste water during washing and
which may contain stagnant water, on ledges, behind
pipework or in most of the other ingenious places in
which it is often found in the workplace.
The widespread introduction of the 'flip flap' type
steel has made it possible for this steel to be fixed, either
temporarily or permanently to the structure of the
slaughter line close to the wash, to the steriliser facility.
