To control food safety, providing barriers to food contamination is a generally applied concept. The first barrier refers to
outside premises, such as fencing, to prevent unauthorized access to the facility. The access of transport vehicles with raw materials and end-products, personnel, domestic and
non-domestic animals should be monitored and controlled.
Factory site drainage and storm water collection must be sufficient; areas within a 3-m perimeter of the factory must be kept
vegetation free to avoid pest breeding and harborage sites; a 10-
cm thick concrete curtain wall around the factory foundation at
least 60 cm below ground discourages rodents from entering
the building; effluent treatment plants and waste disposal units
should be sited such that prevailing winds do not blow microbial and dust aerosols into manufacturing areas.
The second barrier concerns the closing of factory buildings.
All entrances/exits (i.e., window and door openings, openings
for vents, air circulation lines, floor drains, etc.) must be designed for control over access, flow or exit of personnel, raw
and finished food products, air, process aids (process water, process steam, food gases, etc.), waste, utilities (plant cooling and
heating water, plant steam, compressed air, electricity, etc.) and
pests (insects, birds, rodents, etc.). Floor drains must be screened to avoid rats from entering the food plant via sewers; ventilator openings, including vents in the roof, should be screened
to prevent the entry of roof rats, insects and birds; gaps at the
entrances of electrical conduits, process and utility piping,
which are convenient pathways for roof rats, must be closed.
The third barrier is the segregation of restricted areas (zones)
within the plant, each of which have different hygienic requirements and controlled access. The fourth barrier is the processing equipment (including storage and conveying systems),
which must have an adequate hygienic design and must be closed to protect the food product from external contamination.
ZONING: A CORNERSTONE IN
PREVENTION OF FOOD CONTAMINATION
Zone B is an area in which a basic level of hygienic design requirements suffices. It encompasses areas in which products are
produced that are not susceptible to contamination or that are
protected in their final packages. A B0 zone is the area outside
the buildings within the perimeter of the site where the objective is to control or reduce hazards created by unauthorized
personnel entry and hazards created by water, dirt, dust and
presence of animals. B1 zones include warehouses that store
both raw materials and packed processed products, offices,
workshops, power supply areas, canteens and redundant build-ings/rooms. The objective for a B1 zone is to control or reduce
hazards created by birds and pests.
Zone M is an area in which a medium level of hygiene suffices. It includes process areas where products are produced that
are susceptible to contamination, but where the consumer
group is not especially sensitive and where no further microbial
growth is possible in the product in the supply chain. In this
area, product might be exposed to the environment, during
sampling and during the opening of equipment to clear blocka-