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 Processing, packaging, or packing of food takes place in
diverse locations and physical structures and on many different
scales. The overall design of the facility, from receiving area
to shipping dock, is an important consideration in eliminating
opportunities for chemical, physical, and microbial
contamination. Both direct contamination and cross-contamination
of product can be minimized with proper attention to physical
design, construction material selection, and facility traffic
flow.
The building should be designed so that incoming products never
cross paths or co-mingle with finished products. This is a
recommended practice for all processed food operations.
Occasionally, the available space is limited, but physical
separation of zones using walls or other barriers can achieve
adequate separation. In addition, separate or segregated zones for
chemical storage and mixing, and maintenance and fabrication shops
are needed.
A properly designed facility is important because the
additional mixing, processing, and packaging steps that may be
part of food processing increase the opportunity for
cross-contamination. Pallets and bins coming directly from a
supplier may also be a source of contamination. Proper facility
design can significantly reduce this potential hazard. Finally,
processed, but unprotected, product should not be stored in the
same room location with dirty containers and pallets. For example,
the facility should have sufficient storage room space to keep
processed product, which is being held for later mixing and
packaging, separate from incoming and stored materials.
Like the overall facility design, the movement of processing
water, waste streams, airflow, and employees should be planned
with food safety in mind. To conserve water and minimize
wastewater discharge, many facilities recirculate water.
In a similar manner, facilities may design and install an
air-filtration system for central distribution and airflow counter
to product flow. In these systems clean filtered air moves with a
positive pressure from the cleanest areas--packaging and
packing--back toward the receiving area. Positive pressure flow
(backward airflow) helps reduce the chance of air-borne
contamination along the linear facility design. In the same
manner, there should be negative air pressure in the restrooms to
keep air from flowing out of the restrooms. Additional airflow
barriers, such as air-curtains, help to isolate receiving and
shipping areas that may be open to the outside environment.
Processors that use a bulk dump for incoming materials should
consider installing a fixed wall with a pass-through to move
product from outside to inside the facility. This point of
separation will reduce the potential for water moisture or aerosol
in air above or around the dump tank from contaminating the inside
of the processing area during receipt of incoming materials.
Traffic flow from the outside environment and within the
facility should also be carefully planned. Equipment and workers
should not move between segregated areas. Cross-contamination can
be avoided by preventing the movement of lift-trucks, bins, totes,
tools, cleaning implements, clothing, and people from receiving or
storage zones to processing and packaging areas. Color-coding
bins, totes, clothing, cleaning tools, and other items can help
achieve this separation of traffic.
Finally, proper facility design and selection of construction
materials are major contributors to safe food processing
operation. Floors should be designed for easy cleaning. A smooth,
non-porous floor with coving at wall junctions prevents the
entrapment of dirt and debris. Expert advice should be sought to
select materials that facilitate cleaning and sanitation, and to
design adequate floor slope for drainage. Flooring materials
should be suitable for your facility and selected to be resistant
to chemical damage and cracking from equipment movement. Cracks in
flooring are difficult to clean and may easily become a site for
plant residue accumulation and subsequent microbial growth.
Walls should be designed for and constructed of materials that
are readily cleaned and will not serve as a home for pests.
Sealing and screening must be used to exclude pest entry through
windows and vents.
Any access doors leading directly from outside the facility to
the processing and packaging area should be designed with food
safety in mind. An effective design utilizes a double entry
barrier, sometimes in combination with a "forced-air
curtain" to help exclude insects. In this design, each person
must enter self-closing doors, which open in opposing orientation,
left to right then right to left. The doors leading directly to
the outside must first close to allow the second door to open.
Cautionary signs and boot dips alert the worker or maintenance
person that they are entering a clean area. The use of such doors
during operating hours should be strictly controlled. The areas
outside the facility should be designed and maintained to minimize
the potential for attracting or harboring rodents and other
potential sources of human pathogens. Landscape design and weed
control programs should be part of the overall food safety plan.
The location and design of drains, floor flumes, and pipelines
can be made to greatly improve the ease of maintenance and
effectiveness of clean-up procedures. Expert advice should be
sought to design placement or protective aides to prevent pipe and
wall condensation from becoming a source of contamination. Drains
should be fitted with seals and grates capable of preventing
rodent entry. The use of floor flumes should receive careful
consideration because of the potential for water aerosol
contamination of the room air or nearby equipment surfaces. This
is especially true for floor flumes that carry water waste from
one segregated area across another. The design of the collection
area for wastewater should incorporate systems to prevent product
or equipment contamination that might serve as an attractant for
pests.
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