Agriculture Reference
In-Depth Information
in poultry carcase washes to reduce Campylobacter jejuni
on the carcase have also been considered.
Investigations indicate that
acid treatments
are more
effective on adipose tissue than lean meat, and that
while spray treatments with organic acids do reduce
populations of
E. coli
O157:H7 on red meat, neither lac-
tic, citric or acetic acid at concentrations up to 5%
reduced the pathogen levels to zero (Cutter and Siragusa,
1994). Brackett, Hao and Doyle (1994) confirmed that
these acids at concentrations up to 1.5% applied at 20
and 55°C did not appreciably reduce numbers of
E. coli
O157:H7 on beef. In general, it would appear that
although organic acids are successful in reducing the
numbers of spoilage bacteria present on the meat sur-
face, they are of much less use when expected to render
meat safer by removing pathogenic bacteria. The use of
lactic acid is permitted within the EU applied as a 2-5%
solution by spraying or misting, up to a temperature of
55°C. Its use must be within the context of a HACCP
system to visibly clean beef carcases, half carcases or
quarters.
Trisodium phosphate
has been used to reduce the total
viable counts on poultry carcases by 50% and the inci-
dence of salmonella-contaminated carcases from 9.5% to
0%. Phosphates are, however, potential environmental
pollutants.
The abuse of post-processing treatment to mask poor
hygiene practice during dressing and an ineffective
inspection processes must be rigorously opposed. The
FSIS in the United States recognises this and states cate-
gorically that 'antimicrobial treatments will not be per-
mitted to substitute for strict compliance with sanitary
slaughter and carcase dressing procedures, e.g. no visible
faecal contamination will be permitted on the carcase
before the treatment is applied. Suitably controlled, and
as part of an integrated approach to the reduction in the
total numbers of pathogenic and spoilage bacteria pre-
sent on the carcase before it enters the chillers, these
treatments may have an important role to play. Public
demand for meat which is naturally produced and resi-
due-free, however, may make the concept of treating
meat with antimicrobials, acids or high levels of chlorine
difficult to establish.
Ultraviolet and pulsed high-intensity light
The antibacterial activity of ultraviolet light has been
known for over 100 years. Short wavelengths acts upon
the bacterial DNA preventing it from multiplying and
can sanitise the surface of a carcase at exposure times of
10 minutes. It has also been demonstrated to be effective
as a post-packing treatment applied to modified atmos-
phere packs.
Pulsed visible light at wavelengths between 170 and
2600 nm and intensities of up to 50 joules/cm
2
has been
evaluated for treatment of beef and pork for exposures
ranging from one millionth up to one tenth of a second.
At longer exposure intervals and higher intensities, the
surface temperature of the meat heats quickly causing
inactivation of bacteria and, in some cases, cooking at
the meat surface.
A commercial system which has a combination of
pulsed light and ultraviolet is available and is reported to
reduce total numbers of aerobes significantly.
Outputs of the slaughterhouse
Essentially there are two categories of material arising
from the slaughter process - that which goes for human
consumption and that which does not. The former group
is made up of a mixture of that which progresses into
the food chain with minimal processing - the obviously
edible meat - and that which needs significant further
processing before it is suitable for ingestion - the edible
co-product. Of the material that does not go for human
consumption, the animal by-product, some goes as
waste, some to pet food production and some for
technical or pharmaceutical uses.
The principle has already been established that the live
animal, farmed for human consumption, is food. Obviously
the live animal requires a degree of processing for it to
actually be eaten, but virtually all parts of the healthy ani-
mal, with appropriate processing, can be used for human
consumption. Biologically, most non-carcase material is
edible, with appropriate cleaning, handling or processing,
but variable use is made throughout the world owing to
custom, religion, palatability and reputation of the prod-
uct. After the carcase, the most commonly used organs and
parts for human consumption are liver, heart, tongue, kid-
ney, tripe and intestines as sausage casings, except for the
bovine intestine in areas with Specified Risk Material
(SRM) controls. Some cultures will use other parts of the
animal - cattle, pig and poultry feet, pigs' ears, etc.
The edible output from the animal can be subdivided
into those parts where minimal processing is required
Bacteriophages
Bacteriophages (phages) are viruses that attack and kill
specific strains of bacteria. They were first discovered in
the early twentieth century and have been utilised to treat
infectious disease, but in 2006, bacteriophages were
approved in the United States as a 'food additive' that
could be sprayed on ready-to-eat meat and deli products
to reduce the presence of Listeria monocytogenes. This
was followed in 2007 by a bacteriophage product designed
to be sprayed, misted or washed onto cattle hides to
reduce the presence of
E. coli
. Phage products to include
