Steve Bagshaw, Holchem Laboratories
Introduction When products are being prepared in a food plant, no matter how controlled
the conditions are or how automated the production line, surfaces and
equipment will become soiled. Cleaning is essential. As cleaning is
required at a number of stages in food preparation, it is sometimes
considered to be an integral part of a HACCP system. However, as cleaning
is an essential element of good manufacturing practice, it is usually
considered to be a pre-requisite to the introduction of HACCP.
Cleaning products
Cleaning product choice (the detergent or disinfectant) cannot be considered
in isolation from the cleaning method or from the dispense and application
method. A detergent or disinfectant is purely a tool in the overall
cleaning procedure that assists in achieving the required end result;
namely a clean facility that is safe for food production.
Who chooses?
A reputable hygiene support company will have the skill, breadth of
knowledge and interest in helping a food producer with the choices.
It is however advisable, if not essential, to be part of this evaluation
and decision process.
The choice of cleaning regime
The factors that need to be considered when choosing cleaning regime
are:
- The type of clean; for instance is it open plant (conveyor belt
and environmental surfaces) or is it enclosed (sauce vessel) and cleanable
by CIP (Clean in Place)?
- What standards need to be achieved to meet the food safety and shelf
life requirements of the product?
- Will the cleaning regime have an impact on effluent and its treatment?
- What types and mixture of soils are there on the surfaces?
- What is the typical microbial contamination found in the plant?
- What risk will the cleaning regime pose to food, people and equipment?
Cleaning aims to reduce the risk of producing contaminated food. However
there are risks of contamination from the cleaning process. The choice
of when and how to clean is vital to minimize this risk.
- What resources such as labour, time and equipment are available?
What choices are available?
A surface can be cleaned effectively by a number of different cleaning
regimes. One factor that remains constant is the need to supply energy
to the soil to remove it from the surface. In the example of hand cleaning
in a utensil sink, thermal energy comes from the warm water which assists
in the emulsification of any fats, chemical energy comes from the neutral
detergent that allows removal and emulsification of the soil and physical
energy as elbow grease assists with soil removal. Whatever cleaning
regime is chosen the total of these energies must be sufficient to remove
the soil. The more tenuous a soil, the higher the overall energy required.
With numerous detergent products and many cleaning methods it might
be thought there would be an almost infinite number of cleaning regimes
possible. In practice, however, certain combinations of product and
method are not viable; for instance hand cleaning with highly aggressive
caustic or acid products is not safe for the operative. The most common
cleaning regimes are:
Dry clean ~ Wiping, scrapping, brushing and vacuuming of dry
debris are commonly used for dry ingredient areas e.g. bakery. The absence
of water reduces the opportunity for microbial growth but, unfortunately,
does not give good soil removal. Often disposable cloths dampened with
either a water or alcohol based detergent/disinfectant are used to enhance
soil removal in dry environments or where excessive water can be a problem.
Hand clean ~ Hand cleaning utilises the physical energy (elbow
grease) coupled with application of a neutral or mildly alkaline detergent
or as indicated above. A cloth, scouring pad or brush and detergent
from a bucket or sprayer provides a very effective and flexible cleaning
method. However, hygiene and foreign body contamination issues exist
with all cleaning tools:
- Cleaning equipment must be managed.
- Cleaning equipment must be cleaned and disinfected prior to storage.
- Equipment should be colour coded and only used on dedicated surfaces/areas.
- Buckets should not come into contact with floors and then food
contact surfaces.
Soak clean ~ Soak cleaning is used for small items to enhance
contact time with the detergent. It is beneficial on heavy or tenuously
soiled items. Highly carbonised trays e.g. pizza trays can be successfully
cleaned in this manner. Detergents are often highly alkaline and may
need to be formulated to be suitable for use with aluminium. Ultrasonic
energy can be used to enhance soil removal.
Foam or Gel cleaning ~ A foam or gel is simply a vehicle to gain contact
time between soil and detergent. A wide variety of foam and gel products
are available which, when applied to a soiled surface, will remain in
contact for 10 minutes to one hour. This time enhances the chemical
actions between soil and detergent making it easier to subsequently
remove.
The loosened or reacted soil still requires some physical energy to
remove it. This can be provided by a cleaner and a brush and/or by energy
from a washdown system. In many cases some elbow grease is necessary
while the foam detergent is in contact with the soil because the wash-down
system is insufficient on its own.
Washdown systems enable quick removal of oil and detergent from a surface
but will inevitably cause over-spray and in the case of high pressure
systems atomisation carrying debris and microbes from surfaces into
the air and then onto other surfaces.
Foams are applied by variety of application systems (e.g. Jetstream
Foamer). They all have the benefit of keeping the cleaning operative
away from direct contact with the foam and also enable large areas to
be quickly covered. Foam detergents include, neutral, alkaline, caustic,
chlorinated alkaline and acidic products.
- Alkaline products are the most commonly used foam formulations because
of their good all-round performance on fats and proteins.
- The higher alkalinity the better the performance against carbonised
and polymerised soils such as those found in cooking and frying operations.
Products safe for use on aluminium and other "soft metals"
are the neutral and alkaline products; but data sheets must be checked
for compatibility.
- The chlorinated caustic products are highly effective at removing
protein soils and staining. The chlorine donor in the formulation
is primarily there to aid removal of proteins and not as a biocide.
Acidic products are effective on mineral scale and also on proteins.
Automated washing machines ~ Trays, racks, bins and utensils
can be automatically washed using purpose built washing machines. The
machines maximize on the physical energy through the washdown jets,
high temperature and aggressive detergents (e.g. highly alkaline) to
enable quick cleaning. Typically a tray passing through a tunnel traywasher
will be in the detergent zone for only 10 to 20 seconds.
Highly alkaline or caustic based detergents are used for washing plastic
or stainless steel parts. These products are available in different
formulations to suit site water hardness.
Aluminium or tinned utensils are cleaned using either neutral or aluminium
safe alkaline products.
Disinfectants are typically low foam Quaternary Ammonium Compounds
(QAC or Quats) or Amphoterics. An exception to this is in poultry processing
where live bird crate disinfection uses MAFF (DEFRA) approved products
(often peracetic acid based).
Clean In Place (CIP) ~ The brewery and dairy industries have
successfully used CIP for vessels and pipework for over 30 years. The
automated nature and lack of operative contact with cleaning solutions
means that highly aggressive detergents at high temperature can be used.
Caustic/sequestrant detergents are commonly used although acidic products
are better on some soils. Some food processing plant, such as cook~chill
systems, now make use of CIP. Properly designed and managed they provide
excellent performance but the choice of detergent is critical to this
performance. Disinfection uses QAC or Amphoterics terminal disinfectants
or peracetic acid.
 Disinfection
~ Disinfection is part of the whole cleaning regime that is designed
to control the level of microbial contamination in foods to an acceptable
level. Disinfectants must be applied to a clean surface and then left
in contact for a period of time, (typically 15 minutes) before food
production can start. Some disinfectants (QAC and Amphoterics) are of
low taint and toxicity and can be left on a food contact surface without
the need for rinsing. Most disinfectants are supplied with data to support
their efficacy (against a standard protocol) and also an assessment
of their likelihood to taint foods.
Detergent and disinfectants ~ The actions of different types
of detergent and disinfectant have been well documented and reported.
Some points to consider:
- Some plastics are susceptible to stress corrosion cracking when
in contact with the surfactants (wetting systems) used in many neutral
or alkaline products.
- Soft metals such as aluminium and brass are easily attacked by detergents
and disinfectants. This attack is exaggerated by longer contact time
(soaking) and higher temperatures.
- Some plastics are susceptible to stress corrosion cracking when in
contact with the surfactants (wetting systems) used in many neutral
or alkaline products.
- QAC disinfectants are inactivated by the surfactants (wetting systems)
used in most neutral or alkaline products. To avoid this interaction,
rinsing after detergent application is essential; this also ensures
all soil residues are removed prior to disinfection. If any doubt
exists that this rinsing may not occur, compatible detergents and
disinfectants must be chosen.
Conclusion
Cleaning is a pre-requisite to, and an essential part of production.
A clean environment is necessary for safe and efficient food production
and will reduce the risk of pest infestation by removing the materials
that would provide them food or harbourage. A well designed and managed
cleaning regime provides this safe environment for production, prevents
damage to personnel or equipment, maximises the efficiency of equipment
and services, and reduces costs.
Holchem Laboratories 01706 222288
www.holchem.co.uk
SOFHT Focus 33, September 2001
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