(continued from page 28)
“Another means for minimizing cross-
contamination with allergens is through the use
from the environment is dependent
upon a number of variables…” They
listed those as follows:
1. Proximity of microbial growth niches
to the product stream
2. Number of niches in the factory
3. Spatial relationships of niches and
the product stream
4. Microbial population in niches
5. Degree of niche disruption during
6. Exposure of the product stream to
Consequently, sites conducive to
growth (e.g., where moisture has collected or been entrapped) can be broken
down into those areas which are of high,
medium and indirect risk of contaminating the product stream based upon observations and testing. These areas can
be defined as follows:
High risk – an area or practice that
may directly contaminate the product
from a microbial growth niche either
continually or intermittently.
Medium risk – similar to “high risk,”
but mitigating factors (e.g., further heat
processing) may reduce risk by an undetermined amount.
Indirect risk – any situation or condition likely to develop into a microbial
growth niche (e.g., standing water in a
hallway) that may migrate to another site
and become a growth niche capable of
inoculating product at a detectable level.
This approach causes the auditor to
focus his or her observations in the plant
on likely contamination risks to finished
product. It is important to recognize that
test results from samples taken in a plant
are, at best, merely a snapshot of microbiological conditions at those sites at the
moment of sampling. Consequently,
data from testing of such samples taken
should not weaken the force of the initial observation, since a high-risk condition may require more time after the
sample is taken to develop the microbial
populations that may result in direct
measurable contamination of product.
However, the data may reveal areas that
were not obviously a risk during the initial walk through. In my experience, the
biggest surprises often come in the form
of dedicated utensils, containers and tools.”
of pre-operational surface sampling results. Oftentimes, high counts may be
found on surfaces that look visibly clean
and dry after cleaning and sanitization
and before product startup. Frequently,
this phenomenon results from inadequate use of hot water during cleaning,
something that may or may not have
been caught during the observation of
In summary, current checklist approaches may not identify actual microbiological risks, especially when the
auditor is not sampling for them. A
walk-through microbiological risk assessment with environmental sampling and
testing would provide valuable information about the relative risk of a process
and should be used to supplement the
current checklist-based approaches. Such
an approach could help avoid the types
of food safety surprises we have seen in
The next issue of this publication will
discuss how to avoid some of the pitfalls
of the walk-through risk assessment approach.
1. Mead, P. S., et al. 1999. Food-related illness and death in the United States.
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2. www.fsis.usda.gov/OPPDE/Nis/Out-reach/ Listeria.htm#Top.
3. Kornacki J. L. and J. B. Gurtler. 2007. Incidence and Control of Listeria in Food
Processing Facilities, in Listeria, Listeriosis and Food Safety, 3rd Ed. Edited by
Ryser, E. T. and E. H. Marth. Boca Raton,
FL: CRC Press.
4. Tompkin, R. B., V. N. Scott, D. T.
Bernard, W. H. Sveum, and K. S. Gom-bas. 1999. Guidelines to prevent post-processing contamination from Listeria
monocytogenes. Dairy Food Environ
5. Allan, J. T., Z. Yan, and J. L. Kornacki.
2004. Surface material, temperature, and
soil effects on the survival of selected
foodborne pathogens in the presence of
condensate. J. Food Prot 67:2666-2670.
6. Allan, J. T., Z. Yan, L. L. Genzlinger, and
J. L. Kornacki. 2004. Temperature and
biological soil effects on the survival of
selected foodborne pathogens on a mortar surface. J. Food Prot 67:2661-2665.
7. Reij, M. W. and E. D. Den Aantrekker.
2004. Recontamination as a source of
pathogens in processed foods. Int J
Food Microbiol 91:1-11.
8. Gurtler, J. B., J. L. Kornacki, and L. R.
Beuchat. 2005. Enterobacter sakazakii: A
coliform of increased concern to infant
health. Int J Food Microbiol 104:1-34.
9. Gabis, D.A. and R.E. Faust. 1988. Controlling microbial growth in the food-processing environment. Food Technol
Jeffrey L. Kornacki, Ph.D., is President of Kornacki Microbiology Solutions, Inc., a McFarland (Madison), WI-based company. Dr. Kornacki has performed in-factory microbiological
investigations, risk assessments and food safety-related audits for 20 years in approximately
500 food-processing facilities in a variety of capacities with different organizations. Between
2001 and 2003, he was an Assistant Professor at the University of Georgia’s Department of
Food Science and Center for Food Safety prior to starting several food safety consulting
companies. He remains an Adjunct Assistant Professor in the University of Georgia’s Department of Food Science and is also Adjunct Faculty with Michigan State University’s National Food Safety & Toxicology Center. He has researched, published and spoken widely on
pathogen control, testing and sampling in food production facilities. Kornacki Microbiology
Solutions (KMS) provides in-plant services including microbiological risk assessments, troubleshooting and CCP validation. They also develop applied microbiology research protocols,
offer public and private short courses and provide expert witness testimony for their clientele. They can be found at www.kornackifoodsafety.com.