investigatedthe measurementof bothair flowsand airborne microbiological
levels in actualfoodfactories, fromwhichcomputational fluiddynamics
(CFD) modelshavebeendevelopedto predictair and particle(including
microorganism)movements (Anon,2001). Thishas allowed the designof air-
handling systems that providedirectionalair. These moveparticles away
fromthe source of contamination(washrooms,hatches,doorspeople,etc.),in
a directionthat doesnot compromise product safety.
∑ Relative humidityshould typicallybe 60±70%to restrictmicrobial growthin
the environment, increase the rate of equipmentand environmentdryingafter
cleaning operationsand provide operative comfort. Low humidities can cause
drying of the productwithassociatedweightand qualityloss,whilehigher
humidities maintain product quality but may give rise to drying and
condensationproblemsthat increase the opportunityfor microbial survival
and growth.
∑ If the high-riskareais to be chilled,theremaybe conflict between any
national regulationson workroom temperaturesand the desireto keepfood
products cold.To helpsolve this conflict a documentGuidanceon achieving
reasonableworkingtemperatures and conditionsduring production of chilled
foods(Brown,2000)was published,whichextends the informationprovided
in HSEFood SheetNo. 3 (Rev)Workroomtemperatures in placeswherefood
is handled, http://www.hse.gov.uk/pubns/fis03.pdf.
∑ Air-handlingsystemsshouldbe installedsuchthat they can be easilyserviced
and cleaned.
8.4.9 Utensils
Wherever possible, any equipment,utensilsand tools,etc., usedroutinelywithin
highrisk,shouldremain in highrisk. Thismay meanthat requirementsare made
for the provision of storageareasor areasin whichutensilscan be maintainedor
cleaned.Typical examplesincludethe following:
∑ Therequirement for ingredientor product transfer containers (trays,bins,
etc.) should be minimised,but wheretheseare unavoidable theyshould
remain within highrisk and be cleanedand disinfectedin a separatewash-
roomarea.
∑ Similarly,any utensils (e.g. stirrers, spoons, ladles) or other non-fixed
equipment(e.g.depositorsor hoppers) usedfor the processingof the product
should remainin highrisk and be cleanedand disinfectedin a separatewash-
roomarea.
∑ A separatewash-roomarea shouldbe created in which all within-production
wet cleaning operationscan be undertaken.The roomshould preferablybe
sitedon an outsidewallthat facilitatesair extraction and air make-up. An
outside wallalso allowsexternal bulkstorageof cleaning chemicals that can
be directly dosedthroughthe wallintothe ringmainsystem. Theroom
should have its owndrainagesystemthat,in verywet operations,may
includebarrier drainsat the entrance and exit to prevent waterspreadfrom
164 Handbookof hygiene controlin the foodindustry