Food Protection Trends - January/February 2015 - 46

the upper quartile was 0.32 and the estimated probability
of a "no cues" observation falling into the upper quartile
was 0.17. This shows that the proportion of the "no cues"
observations falling into the lowest quartile was greater than
the proportion of those with "cues," while the proportion
of the "no cues" observations falling into the upper quartile
was much smaller than the proportion of those with "cues."
In other words, participants who were not provided with
external food safety cues had a larger proportion of salads
with low contamination levels and a smaller proportion of
salads with high contamination, compared to participants
who were provided with cues.
Relationship between observations and microbiological
analysis
Pearson Correlation coefficients were calculated to identify associations between hand washing and cross-contamination and the level of contamination of L. casei on several
contact surfaces in the kitchen and in the RTE fruit salad
that participants prepared (Table 5). Handwashing was associated with the tracer organism counts on the sink handle,
trash handle, small towel, and the main countertop used for
food preparation. The oven handle and the small towel were
the surfaces associated with the cross-contamination scores
of participants.
DISCUSSION
Ninety percent of the RTE fruit salads prepared by
participants across the three treatment groups were
contaminated at some level with L. casei, and about 24%
were highly contaminated. There was a high frequency and
level on kitchen contact surfaces due to the food handling
practices of participants. Fischer et al. (13) found that 42%
of the variance in log reductions in a finished salad could be
explained by cross-contamination practices of participants.
Nauta et al. (21) concluded that most of the participants
in their study were unable to prepare a salad without
contaminating it with the tracer organism.
There were several potential sources of cross-contamination. Many instances were observed when hands were
not washed or where the techniques used were inadequate,
including at the beginning of food preparation and after
handling raw meat packaging and trash. Handwashing consistently has been identified as a shortcoming in studies in
which consumer activity was videotaped (4, 17, 22, 24).
There were several instances in which the treatment
impacted cross-contamination. The control group had
lower mean handwashing scores than either the AdCM
group or the FSM group. Further, contamination on
oven handles was lower for the FSM group than for the
control group. Differences in contamination levels were
observed on sink handles and RTE salads between the
FSM and AdCM groups, and in both cases the FSM
group was lower.

Food Protection Trends

January/February

Towels were commonly observed to be used multiple
times after people washed their hands, often with no
soap and/or using very short, ineffective handwashing
techniques. This could be one of the most critical findings of
this study, as cloth towels can quickly become contaminated
at significant levels with microorganisms originating from
raw meat and poultry as consumers often use and re-use
the towels to wipe or dry their hands after ineffective
handwashing. This finding is consistent with those of
Cogan et al. (9) and Redmond et al. (23), who found
significant towel contamination after the preparation of a
chicken meal. Cross-contamination events, such as using
the towel to wipe up water from work surfaces and for
drying/wiping unwashed hands, were identified (23). It
should also be noted that some participants chose to use
paper towels in lieu of the provided cloth towels to dry their
hands. Although the used paper towels were not analyzed
in our study, they sometimes were re-used by participants
multiple times during the meal preparation and likely served
as a source of cross-contamination in the same manner as
observed with the cloth towels.
Generally, the spread of L. casei contamination throughout the kitchen during meal preparation, as indicated by
swabbing appliance, sink, and cabinet handles, showed
that raw meat and poultry commonly serve as a food safety
risk because of consumers' propensity to cross contaminate. Handles throughout the kitchen commonly became
contaminated, sometimes at rather high levels (approaching
or exceeding 3 log CFU/area swabbed), during the meal
preparation. Our study monitored these surfaces only at the
end of consumer preparation activities; thus, in some cases
these handles may have become and remained contaminated
during the meal preparation but could have been sanitized
during a final clean up by the participant. In such cases,
our data may not be entirely indicative of the extent to
which kitchen handles contribute to cross-contamination of
ready-to-eat food dishes by potentially harmful foodborne
pathogens. A majority (> 82%) of participants, regardless
of their assigned treatment group, left meat-originating contamination on sink, refrigerator, oven, and/or trash cabinet
handles. The observed contamination levels on these handles were typically low (< 1 log CFU/ handle); however,
in some instances contamination levels approached 3 logs.
The handle of the trash can cabinet was left contaminated
by 86.9% of participants, with a maximum level of 3.61 log
CFU/area swabbed being observed. Similarly, the sink
faucet handle was contaminated by 89.4% of participants
(mean level of ca. 1 log CFU/handle), with a maximum
observed contamination level of 2.61 log CFU/handle. Video observation of participants' meal preparation activities
indicated a very broad set of behaviors (many risky) relative
to disposing of raw meat packages, touching trash can cabinet and sink faucet handles, and subsequent cutting of
fruit salad components. Participants frequently handled

Food Protection Trends - January/February 2015

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