mammary gland (Radke, 2002). Fecal con-
tamination is another alleged major source of
contamination in raw milk. Van Kessel et al.
(2003) evaluated the efficacy of a portable
real-time Polymerase chain reaction (PCR)
system for the detection of salmonella in raw
milk. They found that the portable real-time
PCR techniques yields results in 24 hours
compared with the 48 to 72 hours required for
a traditional culture.
Sanitary construction considerations
The considerations most important to
dairy plant sanitation are drainage and waste
disposal. Storm and sanitary sewers must be
adequate and readily available. In rural areas
and municipalities with limited treatment
facilities, dairy processors frequently must
provide their own waste disposal facilities.
An adequate supply of potable water and
acceptable drainage and waste disposal are
essential. Other considerations are men-
tioned in Chapter 14.
Floor Plan and Type of Building
The layout and construction of a dairy
plant are subject to the approval of one or
more regulatory agencies. All equipment
and utensils should be purchased subject to
the approval of the various regulatory
authorities.
Ventilation is important, especially in
areas where excess heat produced during
processing must be removed. The ventilation
should be tailored to the different types of
rooms and should have the flexibility to meet
the needs of any future alterations in pro-
duction. It is frequently necessary to filter
incoming air, especially if the plant is located
in a heavy industrial area. Also, the control
of humidity, condensation, dust, and spores
should be considered.
Construction Guidelines
Unless construction is carefully planned,
the structure and equipment can contribute
to contamination. This problem can be
helped by reducing overhead equipment to a
minimum, which reduces contamination due
to maintenance of this equipment. Overhead
equipment is also difficult to clean. A sepa-
rate service floor that will accommodate
a major portion of the ducts, pipe works,
compressors, and other equipment should
be provided. This arrangement results in a
clear ceiling, which is easy to clean and keep
sanitary.
Some other design and construction char-
acteristics that are conducive to effective san-
itation are:
●All metal construction should be treated
to withstand corrosion.
●Pipe insulation should be of a material
that is resistant to damage and corro-
sion, and will endure frequent cleaning.
●Chronic condensation points should be
protected by the installation of a
drainage collection system.
●All openings should be equipped with
air or mesh screens and tight-fitting
windows.Structural finishes should be of materials
that require minimal maintenance. Walls,
floors, and ceilings should be impervious to
moisture. Floor materials should be resistant
to milk, milk acids, grease, cleaning com-
pounds, steam, and impact damage. Epoxy,
tile, and brick are good choices. Paint should
not be used if suitable alternatives exist. If
paint is applied, it should be of a grade that
is acceptable for food plants. Floor drains
should be designed to control insect infesta-
tion and odors. A slope of approximately 2.1
cm/m is recommended to reduce accumula-
tion of water and waste on the floor, which
could hamper the sanitation and lead to
growth ofL. monocytogenes.