The correct design of equipment and facilities is an important aid to thorough cleaning as it
prevents soils and associated micro-organisms from building up and contaminating foods. In
this technical brief some simple principles are described which can be used to check the design
of locally made or imported equipment and the facilities for creating adequate hygienic
standards. Correctly designed, easily cleaned equipment and facilities also promotes better
hygienic standards by operators - people will clean a piece of equipment regularly and properly if
it is not difficult whereas a time-consuming and laborious cleaning procedure is more likely to be
ignored or only partly done.
A food processing unit should not be located near swamps, ditches, refuse dumps or other
places where insects and rodents are likely to be found in large numbers.
The site should allow wastewater to drain away freely and have suitable facilities for removing or
disposing of waste food, peelings etc outside of the site. A supply of clean water is usually
The site itself should be cleared of undergrowth and kept clean of debris and waste food which
would attract rodents. Trees provide useful shade, but also attract birds which are a potential
source of contamination of foods.
A clean uncluttered room gives a good impression to visitors and inspectors and also encourages
good hygiene practices by the workers. Walls and floors should be smooth for easy cleaning and
free of cracks in which liquids and bits of food can collect. The room should ideally have a
ceiling, which prevents dust falling from rafters into the food and helps keep birds and insects
Where possible pipes and cables should be laid together and covered for easy cleaning. High
level pipes are more difficult to clean and collect dust which can fall into the food or equipment.
Window ledges should be sloped for the same reason, and also to prevent people leaving cloths,
bottles etc lying around.
The type of material used in the construction of equipment is an important factor for ease of
cleaning. Wood is used for barrels, vats, bins and sometimes for machine supports when metal
is too expensive. It is also widely used for chopping/cutting boards. However, wood is difficult
to clean properly, particularly when used as chopping boards, as soils collect in cracks and
fissures. If possible, metals and plastic should be used in place of wood, although this will
increase the cost of the equipment. If wood is used, particular attention should be paid to
thorough scrubbing with detergents and sterilants.
Cast iron has similar problems to wood and the above comments apply. Iron rusts easily and not
only becomes difficult to clean, but also risks contamination of food with pieces of rust. It
should be painted if it is used in a processing room but it should never be used in contact with
wet foods and especially not with acidic foods such as fruit products, yoghurt etc. Stainless steel
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Food Processing Equipment Design
is the preferred material for these foods but it is expensive and often unobtainable, plastic is a
suitable alternative if these foods are not heated but there is no alternative to stainless steel for
heating acidic foods. Low acid or dry foods do not have the same problem and aluminium,
galvanised iron, enamelled iron and even brass or copper vessels can be used. However, the last
two should never be used in contact with oils or fats and aluminium should not be used with
meat. In each case the metal surface should be polished smooth for easy cleaning.
Metal joints should ideally be welded with a continuous weld which is ground to a smooth finish
with a grinding tool. Crevices, cracks, weld debris and burrs should be removed by grinding and
inside corners of equipment should have a radius greater than 1/4 inch. These precautions
prevent the accumulation of food and allow easy cleaning. If welding is not possible, metal joins
can be pop-riveted and sealed with a strong adhesive such as 'Araldite'. Solder can also be used,
subject to the above precautions and provided that the solder contains at least 50% tin and is
free of poisonous metals such as cadmium and antimony.
All bearings leak oil or grease to some extent and they should therefore be positioned outside of
the equipment so that they cannot come into contact with the food.
Figure 1: Support leg design to prevent soil accumulating
Electrical wires should be grouped together where possible and placed inside a smooth conduit
for easy cleaning and protection from water splashes. Electric motors should be enclosed for
similar reasons. Pipes for steam and hot water should be insulated for safety and the insulation
should be covered with a smooth material for easy cleaning. All pipes should be at least 6" from
a floor or wall to allow cleaning behind them.
Machines should be supported off the floor for proper cleaning underneath. The place where the
support legs meet the floor should be carefully designed to prevent soils accumulating see Figure
1. A minimum number of supports should be used.
The insides of pipes and equipment should be easily accessible for cleaning with brushes.
Dead-ends to pipes should be avoided and all bends should be smooth and never right-angled. A
useful rule is that the radius of the bend should not be less than the outside diameter of the
pipe. Pipe joints are needed to gain access for cleaning and these are a particular source of
contamination. Ideally, a sanitary metal pipe fitting, which has no internal thread, should be
Food Processing Equipment Design
However, these may be unavailable and particular care is therefore needed to dismantle and
thoroughly clean pipework and valves at regular intervals. Food grade plastic pipes are suitable,
provided that the diameter is large enough to allow cleaning with a bottle brush. Pipework and
other equipment can be 'cleaned in place' by passing detergent and sterilant through them.
However, technical advice should be sought if this is planned to ensure that the cleaning is
Hand tools such as knives, peelers etc should be checked to make sure wooden handles are not
cracked or split. They should be scrubbed, dipped in a dilute chlorine solution and hung up to
dry. Cloths, towels etc should also be regularly washed and hung up to dry. Wet cloths should
never be left inside equipment.
Ideally, these should have a metal or melamine surface that is smooth and free of cracks for easy
cleaning. However, wood is cheaper and is widely used. If possible, tables should be covered
with a layer of plastic to prevent liquids and pieces of food collecting between the planks of the
Reference and further reading
Food Processing Building Design Technical Brief, Practical Action
Food Poisoning & Its Prevention Technical Brief, Practical Action
Quality Assurance for Small-scale Rural Food Industries FAO Agricultural Service Bulletin 117, Food
and Agriculture Organization of the United Nations 1995
Starting a Small Food Processing Enterprise by Peter Fellows, Ernesto Franco & Walter Rios
Practical Action Publishing/CTA 1996
Small Scale Food Processing 2nd Ed. P Fellows & S Azam Ali, Practical Action Publishing, 2003
The Schumacher Centre
Rugby, Warwickshire, CV23 9QZ
Tel: +44 (0)1926 634400
Fax: +44 (0)1926 634401
Practical Action is a development charity with a difference. We know the simplest ideas can have the
most profound, life-changing effect on poor people across the world. For over 40 years, we have been
working closely with some of the world’s poorest people - using simple technology to fight poverty and
transform their lives for the better. We currently work in 15 countries in Africa, South Asia and Latin