Food Protection Trends - September/October 2022 - 387

Figure 2. (A) Schematic diagram of a high hygiene meat slicing factory, where meat logs are brought into the high hygiene zone via log washer,
stored on racks, nitrogen chilled prior to slicing, and packed. On top of this diagram can be added various flows, e.g., (B) air movements,
(C) rack movements, and (D) production operatives, which can help identify potential Listeria environmental cross-contamination vectors.
cally reviewed. For RTE food manufacturers, this will be essential
because the outputs of the PEP, particularly any requirements for
capital expenditure projects such as building refurbishment, are
likely to be critical in practically controlling Listeria.
Step 2. Define the scope or the terms of reference. The
processing area(s) for the study should first be determined,
typically the high hygiene area. The types of potential sources
and routes (vectors) of environmental contamination transfer
may need defining, particularly if these have already been
considered at the generic prerequisite stage of the HACCP
study, e.g., compressed air or the potable water supply.
Step 3. Select the PEP team. Because the study will assess
Listeria sources and vectors within a given process area, many
activities and events may occur in this area at different times
of the day, week, year, or other frequency; and the selection
of team members should reflect all of these activities. A PEP
team (which may be the HACCP team) is likely to consist
of members of engineering, production, technical, quality,
and hygiene; hazard specialists such as microbiologists; and a
scribe. Consultants can be used for their technical knowledge,
but they should not write the plan. The PEP should be owned,
written, implemented, and managed by the food manufacturer.
Step 4. Describe the environment. All physical and
operational parameters of the processing environment under
study should be recorded and/or measured with due regard to
activities in adjoining processing areas, adjacent to, below, or
above the area of study. The physical properties will include the
size and layout of the processing area; any zones of segregation;
entrance barriers into the area; services flowing through
or above the area; air flows, temperatures, and humidity;
personnel flows; transport flows for product and packaging
and solid and liquid waste streams. Operational activities
will include products processed, production lengths, and
seasonality; housekeeping, end-of-production, and periodic
cleaning and disinfection practices; quality control inspection
and sampling activities, maintenance activities, and shut down
periods.
With respect to Listeria detections, any historical data from
previous routine sampling should be recovered and reviewed.
Step 5. Susceptibility of the product to be crosscontaminated.
This clause has been modified from the
original step 5 of the Gaze HACCP study, which was " identify
intended product use. " For this clause, any properties of the
product should be determined that would prevent or restrict
Listeria cross-contamination from the environment. For
example, for hot product entering the high hygiene area from
a cooking process, when does the product cool sufficiently so
that any Listeria cross-contamination would survive on the
product surface?
Step 6. Construct flow diagrams. All information collected
during step 4 should be recorded in the form of physical maps
or diagrams of the processing area. Ideally, this should start
September/October Food Protection Trends 387

Food Protection Trends - September/October 2022

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