cleaning operations to keep pace with new
materials and cleaning and sanitizing equip-
ment. These advances have enabled the formu-
lation of specific cleaning compounds that
adapt to water conditions, types of metals, and
soil characteristics. They also have the buffer-
ing ability to minimize corrosion. They have
opened up a new avenue of close union and
intimate association between cleaning com-
pounds and sanitizing agents to enhance the
value of both phases of sanitization.
Role of pathogens
Despite the industry’s reputation for
hygienic design and practices, pathogens have
continued to invade dairy products. During
1985, a large outbreak of salmonellosis
occurred in pasteurized milk. Other recent
foodborne illness outbreaks from the inges-
tion of dairy products have included staphylo-
coccal food poisoning caused by ice cream, the
implication of campylobacteriosis that has
occurred sporadically without a finite determi-
nation of the mode of transmission, and liste-
riosis from contaminated cheese. The latter
outbreak was responsible for several deaths.
As a result, the dairy industry has had to make
a large number of product recalls at great
expense. These events have brought the full
force of the regulatory agencies upon the
industry and motivated several dairy proces-
sors to invest heavily in the improvement in
sanitation of their production facilities. These
experiences have underscored the importance
and urgency of effective sanitation programs.
Because pathogens are discussed in Chapter 3,
only Listeria monocytogenesandEscherichia
coliO157:H7, the pathogens of greatest con-
cern in dairy products, will be discussed here.
Listeria monocytogenes
The discovery ofL. monocytogenesin fer-
mented and unfermented dairy products has
prompted food manufacturers to renew their
concern about plant hygiene and product
safety.L. monocytogenesis widely distrib-
uted in nature and often carried in the intes-
tinal tract of cattle. Approximately 5% of
normal, healthy humans are fecal excretors
of this microorganism. Approximately 5% to
10% of raw bovine milk is contaminated
with L. monocytogenes. This microbe has
been isolated from improperly fermented
silage, leafy plants, and the soil-the latter
being a reservoir ofListeriaorganisms.
Listeria recalls of ice cream and cheese
products have precipitated major processing
and sanitation operation changes in dairy
processing plants. Many processors are volun-
tarily adopting Grade A standards required
for the production of pasteurized milk. The
importance of an effective sanitation program
to combat L. monocytogeneshas contributed
to major increases in training, supervision,
total employee count, and salaries of sanita-
tion workers in dairy processing plants.
The epidemiologic implication of pasteur-
ized milk in the Massachusetts listeriosis
outbreak in 1983 and in the outbreak in Los
Angeles in 1985, attributable to a Mexican-
style soft cheese, led to the establishment of
the U.S. Food and Drug Administration
(FDA) standard methodology for detection
of this pathogen. These events also con-
tributed to a decision to conduct a large sur-
vey for pathogenic microorganisms in the
dairy industry. This survey revealed that, in
nearly all instances, post-processing contam-
ination was responsible for contamination of
L. monocytogenes.
Specific guidelines have been developed
for controlling L. monocytogenes in dairy
processing facilities in the United States.
These guidelines stress the need to: (a)
decrease the possibility that raw products
will contain Listeriaorganisms; (b) minimize
environmental contamination in food pro-
cessing facilities; and (c) use processing