Food Protection Trends - March/April 2023 - 136

Cleaning the cleaning tools
The condition and suitability of the tools and equipment
used in cleaning and sanitizing are often overlooked. In a
1998 microbiological survey of food manufacturing plants in
the United Kingdom, 47% of cleaning tools tested positive
for L. monocytogenes (70). The potential to cross-contaminate
food-contact surfaces is significant when cleaning tools are
not routinely cleaned and sanitized. Inappropriate design of
cleaning tools may lead to inadequate contact with surfaces
such as sharp angles or curves. Cleanliness of the cleaning
tools is receiving more attention in food safety programs,
as indicated by the recent addition to food safety schemes
approved by the Global Food Safety Initiative, and is also
influencing tool design and cleaning and maintenance
protocols and schedules (148).
Studies in packing, processing, and retail establishments
provide examples of how cleaning equipment can become
sources of contamination when not properly maintained. In
a microbial survey of fresh-cut vegetable production plants,
Lehto et al. (98) reported a mean aerobic plate count of 80
CFU/cm2
cm2
and a mean Enterobacteriaceae count of 49 CFU/
on the surface of floor cleaning equipment. Conveyors,
floors, and gloves had elevated aerobic plate counts (50 to 72
CFU/cm2
) even after they had been cleaned (98).
Cloths and squeegees may be used to wipe debris and dirt
from equipment surfaces during harvesting and field-packing
activities. In their survey of 30 produce retail environments,
Burnett et al. (22) swab sampled squeegees and other floor
cleaning tools; at one retail location 33 of 180 sampled tools
were positive for L. monocytogenes and 1 tool was positive
for Salmonella. Cleaning cloths (n = 1,132) used to clean
surfaces in preparation for service of ready-to-eat foods
in U.K. foodservice and retail establishments had higher
aerobic plate counts and higher levels of Enterobacteriaceae,
E. coli, and Staphylococcus aureus than did the surfaces they
were used to clean (139). Kusumaningrum et al. (93) also
reported high levels of Salmonella and S. aureus on regular
and microfiber cleaning cloths but not on disposable cloths
treated with antibacterial agents, which had no detectable
contamination. Cleaning cloth material may hence affect
cleaning efficacy and cross-contamination of surfaces being
cleaned (61).
Tools used to clean harvest equipment may spread
contamination to equipment surfaces. Goulter et al. (65)
reported transfer of bacteria from contaminated cleaning
water to surfaces wiped with cloths that had been dipped in
the contaminated water. Water containing QACs prevented
bacterial transfer but did not stop transfer of bacterial spores
to surfaces via the wiping cloths. Squeegees used to remove
condensation from overhead pipes in a food manufacturing
facility had extensive Listeria contamination when used to
wipe inoculated pipe surfaces (109). Sanitizer alone was
able to remove only 1 to 2 log CFU/in2
(6.45 cm2
) from
squeegee blades, but the bacterial levels were further reduced
136 Food Protection Trends March/April
by 3 to 4 log CFU/in2
after an extensive cleaning regimen
was implemented. Tools and equipment such as those
evaluated in these studies (22, 61, 65, 93, 98, 109, 139) are
used for cleaning harvesting equipment. In contrast to tools
used indoors, tools used to clean harvesting equipment may
have significant exposure to UV light between cleanings;
nonetheless, each cleaning tool should be routinely cleaned
and sanitized at a frequency that is appropriate for how it
is used and stored. Observations reported by a workgroup
during the deep cleaning of harvesting equipment (37)
indicated that much greater attention and emphasis on the
physical condition of cleaning tools, especially brush heads,
is warranted.
Equipment storage
As noted above, during harvesting season, harvesting
and field-packing equipment are typically moved between
harvesting locations and remain outdoors, uncovered
either overnight or when not in use counter seasonally.
When harvesting equipment is removed from storage
after an extended period such as counter seasonally, the
preoperational SOPs should include preventive maintenance,
deep cleaning, sanitation, and verification of the hygienic
state before use in harvesting activities. Storage of equipment
uncovered outdoors leaves it vulnerable to microbial
contamination from pests, blowing dust and dirt, and
moisture, which supports pathogen growth and biofilm
formation (68). When harvesting equipment is cleaned
and sanitized immediately after use and then subsequently
remains inactive outdoors-whether overnight or for several
days or months between uses-this down time provides
opportunities for microbial contamination. Use of coverings
or portable storage structures for inactive equipment is a
possible preventive measure. The time between cleaning and
sanitizing activities and equipment use can be decreased by
performing those activities immediately before harvesting
operations, which reduces the potential for microbial
contamination during down time; however, this order
of operations may not always be logistically possible. As
an alternative, design and construction of equipment
incorporating antimicrobial materials would support
sanitation maintenance when equipment is both operating
and inactive.
New materials and coating technologies
Research focusing on how to maintain surfaces in a
sanitary state with less frequent cleaning and sanitizing
activities has been largely driven by medical applications
but has also become increasingly important to the food
industry as more activities become automated. Automated
processes typically involve more surfaces that are then
available for potential bacterial contamination, increasing
the opportunity for cross-contamination of product (11).
Surfaces constructed with materials that have antifouling or
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