can often be testedto provide an estimate of surfacecleanliness as can the
quality of the first productrun after,for example, a weekendshut-down.
One approachis to designate surfacesas foodcontact, generalenvironmental,
handcontact and cleaning(equipment/cloths). The latterneedcare and attention
and can act as vectorscausing the zig-zagspread of pathogenswithinan
environment(Harrisonet al., 2003).An alternativeis to organise areasinto high
risk and low risk. Greatestemphasisin cleaningbeingdirectedtowardsthe high-
risk or high-careareas,whereready-to-eat foodsare handled.A thirdoption
(ICMSF, 2002),a variationof the highrisk/lowrisk,is to arrangeareas into
zonesor shells (see Fig. 36.10). This essentially establishes successively
`cleaner zones' and/or zonesof increasedsamplingfrequency and decreasing
levels of contamination.
Zone 1 representsthe most critical areasof cleaning ± mainlysurfaces in
contact withready-to-eatproducts, e.g. conveyor beltsand cutters. Fillingand
depositing heads,spraydryingor cream depositers can be particularly difficult
to clean effectively.
Zone 2 couldincludehandcontact areasin closeproximity to zone1 and may
evenincludethe surfaces used/touchedduringhand-washing (Griffithet al.,
2003).Zone2 wouldalsoincludeenvironmentalareasin closeproximity to
Zone 1. The lattermaybe goodlocationsfor the survivalof organismssuchas
Listeria. AnyListeriacontrol strategyshould concentrateon eradicationof
Fig. 36.10 Organisationof areas,basedon risk,to determinesamplingfrequencyand
stringency.The preciseallocationof areasinto zoneswill,to someextent,be product-
and plant-specificand the figureis indicativeonly.Microorganismscan eailybe spreadin
foodpremisesand molecularsub-typinghas shownthat pathogenscan persistfor yearsin
the environment,evenafterso-calleddeepcleaningto eradicatethem.
612 Handbookof hygiene controlin the foodindustry