microorganisms are somewhat weak, and
prompt intervention from sanitation can
be essential for their removal. Depending on the type of microorganism, bacteria in a biofilm use motility appendages
(e.g., fimbriae, flagella, pili) and polysaccharide substances that they can secrete
through their membranes to assist in the
process of attaching themselves to
surfaces.
The conditioning layer formed by nutrients and substances secreted by the
microorganisms involved provides the
environment where even injured cells
can repair and multiply. Those bacteria
in the film continue to secrete a polysaccharide substance that acts as cement,
making the attachment to the surface
very difficult to remove, and protects the
bacteria in the colony against cleaners
and sanitizers. Biofilms may contain
pathogens such as Listeria monocytogenes,
Staphylococcus aureus and Salmonella
among others.
Determining whether biofilms are
present on equipment surfaces can be
achieved through different methods. The
most inexpensive approach is the use of
one’s senses. During visual inspection,
biofilms may be detected by a rainbowlike appearance on stainless steel. Touch
can be used as well; a good indication
that a biofilm is occurring is if there is a
slimy feel over what looks like an otherwise clean surface. Adenosine triphosphate (ATP) bioluminescence devices
that can be used to detect the presence
of organic materials may not detect the
presence of mature films.1 However, ATP
technology can still be used during the
elimination of biofilms to give an indication of the progress being made. Biofilms can also be detected through
microbial sampling of the equipment,
and sporadic spikes in environmental
sampling reports can be tracked. Such
spikes, although sporadic, require immediate attention and corrective actions to
prevent them from reoccurring. Microbial swab samples can be taken to verify
sanitation effectiveness through testing
for indicator organisms like aerobic plate
count and coliforms. Positive coliform
testing results could be used as an indication that the sanitation process is inadequate. Microbial testing can also be
used to validate high ATP results.
“Biofilms can establish themselves on almost any
surface in the food production environment.”
The Role of Sanitation
Whether you are dealing with a dairy,
bakery or a meat packing plant, a good
sanitation program plays a key role in
preventing biofilms from establishing
permanently on processing equipment.
All sanitation programs must have a
balanced combination of physical and
chemical methods to assist in the cleaning process. Physical cleaning methods
may involve manual scrubbing, clean
out of place (COP) and clean in place
(CIP). Chemical methods involve knowing what types of soils are present in the
production environment, selecting the
right cleaning chemicals in order to effectively remove food particles and
choosing the right sanitizers accordingly. Chemical application is also affected by what type of physical cleaning
will be applied. No matter what cleaning procedure will be used, there are
four main factors that should be taken
into consideration, and they work just
like Critical Control Points in a Hazard
Analysis and Critical Control Points
(HACCP) plan. Those factors are time,
temperature, concentration and mechanical action.
Remember that long production
schedules allow more time for microorganisms to multiply and establish themselves on equipment surfaces. Good
operational sanitation practices help to
control microorganisms until wet cleaning cycles are performed. Adequate time
should be provided to perform wet
cleaning thoroughly and, when chemicals are applied, adequate contact time
with equipment surfaces should always
be allowed so they can effectively work
on soils. All product labels should be
read thoroughly and manufacturer’s recommendations followed.
Water temperatures should typically
be 140–160 °F, but no less than 120 °F
and no more than 160 °F. Some chemi-
cal compounds work well with warm
water, while some work well at ambient
temperature. Water at a temperature of
180 °F (the temperature permitted by the
U.S. Department of Agriculture and
U.S. Food and Drug Administration in
lieu of a chemical sanitizer) actually aids
in the formation of biofilms. 2 Keep in
mind that hot water can denature pro-
teins, create baked-on soils on surfaces,
cause the precipitation of minerals and
make removal of biofilms more difficult.
