clearance over each piece of equipment
should be provided to permit effective clean-
ing. Floor-mounted equipment should be
either sealed directly to the floor or mounted
at least 15 cm from the floor. The processing
layout should permit the location of equip-
ment for accessibility to maintenance, sanita-
tion, and inspection. Areas that are difficult
to reach and clean are less likely to be
cleaned frequently and thoroughly.
Stainless steel incorporated in equipment
and facility construction should be protected
from corrosion and potential microbial con-
tamination. Corrosion resistance is enhanced
through passivation-a cleaning and corro-
sion protection treatment for stainless steel
and other metals accomplished with an acid
solution that removes contaminants from the
metal surface and coats the surface in a pro-
tective film.
According to Stanfield (2003), equipment
openings and covers should be designed to
protect stored or prepared food from con-
taminants and foreign matter that may fall
into the food. If an opening is flanged
upward and the cover overlaps the opening,
contaminants, especially liquids are pre-
vented from entering the food-contact area.
Failure to provide parts that extend into the
food-contact areas with a watertight joint at
the point of entry into the food-contact area
make cause liquids to contaminate the food
by adhering to shafts or other parts and run-
ning or dripping into the food. An apron on
parts extending into the food-contact area is
an acceptable alternative to a watertight seal.
If the apron is not properly designed and
installed, condensation, drips, and dust may
gain access to the food. Equipment contain-
ing bearings and gears that require lubri-
cants should be designed and constructed to
prevent lubricant leaks, drips, or entry into
food or onto food-contact surfaces. Con-
denser units that are an integral component
of equipment should be separated from the
food and food-storage space by a dust-proof
barrier. A dust-proof barrier between the
condenser and food storage areas of equip-
ment protects food and food contact areas
from dust contamination that is accumulated
and blown about during the condenser’s
operation.
Airborne contamination is attributable to
the cause of some pathogenic contamina-
tion. Unfiltered air and negative air pressure
in areas where the product is exposed con-
tribute to microbial contamination in the
plant environment. Thus, airflow design is as
important to hygiene as is the design and
construction of floors, walls, and ceilings.
The zone with the highest pressure should be
the area where the product is last exposed to
the open air and packaged. The airflow from
this zone is outward to the processing/prepa-
ration area and on to the storage zone. Dust
collection is more effective if conducted
under a positive pressure.
If an air handling system is currently
designed, the opening of an outside door
provides an air stream exiting the building;
whereas, in a negative air pressure situation,
an opened door causes an incoming breeze
containing outside contamination. The con-
tinual influx of unfiltered air complicates the
overall cleaning of a plant, equipment, over-
head pipelines, and other structural features.
An air filtration system with a nitrogen gen-
eration unit is being installed in high mois-
ture food plants to improve hygienic
conditions. Sterile filters can remove more
than 99.99% of 0.01 mm diameter particles
and 100% of all visible particles. Membrane
nitrogen generators convert air into nearly
pure nitrogen that is injected into packages
to eliminate oxygen that can reduce storage
life.
Appropriate design is essential to prevent
growth niches. There are many possible
mechanisms: aerosols, stress cracks (caused
by fluctuating pressures) in walls coveredSanitary Design and Construction for Food Processing 261