Chapter 5 Food Contamination Sources
Food provides an ideal nutrition source for
microorganisms and generally has a pH value
in the range needed to contribute to prolifera-
tion. During harvesting, processing, distribu-
tion, and preparation, food is contaminated
with soil, air, and waterborne microorgan-
isms. Extremely high numbers of microorgan-
isms are found in meat animals’ intestinal
tracts, and some of these find their way to the
carcass surfaces during harvesting. Some
apparently healthy animals may harbor vari-
ous microorganisms in the liver, kidneys,
lymph nodes, and spleen. These microorgan-
isms and those from contamination through
slaughtering can migrate to the skeletal mus-
cles via the circulatory system. When car-
casses and cuts are subsequently handled
through the food distribution channels, where
they are reduced to retail cuts, they are sub-
jected to an increasing number of microor-
ganisms from the cut surfaces. The fate of
these microorganisms and those from other
foods depend on several important environ-
mental factors, such as the ability of the
organisms to utilize fresh food as a substrate
at low temperatures. In addition, oxygenated
conditions and high moisture will segregate
the microorganisms most capable of rapid
growth under these conditions.
Refrigeration, one of the most viable
methods for reducing the effects of contam-
ination, is widely applied to foods in com-
mercial food processing and distribution.
Its use has prevented outbreaks of food-
borne illness by controlling the microbes
responsible for this condition. However,
correct techniques for cold storage fre-
quently arenot followed, and food contami-
nation may result. The growth rate of
microorganisms may sustain a large increase
in an environment slightly above the minimal
temperature required for growth. Generally,
foods cool slowly in air, and the cooling rate
decreases with increased container size.
Therefore, it is difficult to properly cool large
volumes of food. Many of the Clostridium
perfringensfoodborne illness outbreaks have
been caused by the storage of a large quan-
tity of food or broth in slowly cooling
containers.
Identification of contamination sources
in a food production facility impacts
directly the ultimate effectiveness of an
establishment’s sanitation control strategies.
Both direct and indirect food-contact sur-
faces, water, air, and personnel are primary
areas of concern as contamination sources
in a food plant. Food products may transmit
certain microorganisms, causing foodborne
illness from infections or intoxications.
Foodborne infections can result in two
ways:76