Agriculture Reference
In-Depth Information
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It can end up washed into the drainage system, either
causing blockage in traps or high solids/biological
oxygen demand (BOD) in the effluent.
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It encourages the cleaning team to miss areas, not to
check their work, and to cut other corners.
A poor gross clean is the single biggest reason for poor
or inconsistent bacterial counts on surfaces and for high
bacterial contamination in aerosols caused by rinsing.
In a properly managed cleaning programme, all pieces
of food product, meat, etc. which are larger than a fin-
gernail are removed before application of detergent.
Where possible, this should be carried out dry by
hand-picking, scraping and shovelling. All rubbish/
waste collected should be put in bags/bins and removed
entirely from the area. It should be understood that all
edible foodstuffs and product packaging should be
removed before this stage. (It is a constant source of
amazement how often this simple fact is ignored.)
Foaming should be methodical and thorough, and the
operator should check to see that all surfaces have been
covered in the foam, both top and bottom. Foam con-
centration, dryness, thickness of application and contact
time (15-30 minutes) are all very important in ensuring
the correct results at a controlled, optimised cost.
Post-rinsing
Post-rinsing is again a very important stage. Care should
be taken to minimise the amount of splash and aerosol
formed, which may re-contaminate previously cleaned
surfaces or blast particles of dirt high up on walls and
ventilation socks. After post-rinsing, the surfaces should
be free of all visible particles, layers of soiling and resi-
dues of detergent and should be 'visibly clean. The soil
and detergent residues and any soaps formed by alkaline
hydrolysis of fats will tend to neutralise the disinfectant
properties of quats. It is important to check the efficacy
of the rinse, especially where parallel production lines
are cleaned in sequence and splash could re-contaminate
previously cleaned surfaces. The rollers of conveyors are
particularly important. After rinsing, any pools of water
should be removed from surfaces and vessels, whether
disinfection is to follow or not.
Pre-rinsing
The purpose of pre-rinsing is to remove deposits, which
cannot easily be removed by picking/scraping/shovel-
ling, for example, blood, manure, small meat pieces and
particles, etc. The rinse water should not be used as a
brush for chasing large amounts of pieces around the
floor and towards the drain. This would result in waste
of water and time, blockage of drains, loading of effluent
water with high volume and BOD/chemical oxygen
demand (COD) and unnecessarily high humidity.
Pre-rinsing is particularly important in the case of
cutting boards, where the thick deposits of grease would
make true cleaning of the surface grooves and crevices
impossible. Where fresh blood is a problem, the rinse
temperature should be below 50°C to avoid coagulation.
After pre-rinsing, it is important to remove any water
that may be lying in pools on flat surfaces as these would
dilute the detergent solution and make it less effective.
Any squeegee used to scrape off the excess water must be
used only for food contact surfaces and not for floors.
Disinfection
Disinfection should only be carried out on a visually
clean, well-rinsed surface, free of residual surface water.
Direct food contact surfaces should be disinfected at
least daily, with other surfaces (such as walls, doors, etc.)
disinfected on a regular basis. The concentration of the
disinfectant and its contact time (ideally >20 minutes)
are both very important.
Terminal rinsing
Some disinfectants are suitable to leave on surfaces
without final rinsing. The residual disinfectant often
helps maintain a low microbial count for a considerable
time after the cleaning sequence is finished, particularly
important in dealing with any 'settling' aerosols. In addi-
tion, it provides more time for the surfaces to dry com-
pletely compared to carrying out a terminal rinse, which
sets the drying time back again. The law surrounding
terminal disinfection is currently different in many EU
member states. Some have no official control require-
ments, while others have long-standing approval pro-
cesses. The new EU directives, as previous versions, are
not very descriptive about cleaning and disinfection pro-
cedures. There is of course an absolute requirement to
clean and disinfect as appropriate, provide personnel
hygiene facilities and ensure factory design that is suited
to cleaning. There is no specific instruction about
rinsing of terminal disinfectants other than the linked
Detergent application
The purpose of a detergent is to remove the thin tena-
cious layers of protein, grease, etc. that are still on sur-
faces which may already look clean. Detergents are not
designed for removing large pieces of meat or thick lay-
ers of fat. Although they may seem to help in the removal
of such large quantities, they will usually fail to remove
the last residues actually bonded to the surface if these
residues are protected by the thicker layers above them.
It is in these thin residues that many bacteria can easily
survive and grow and they can make any disinfectant,
which is applied later, ineffective.
