35.2 Background
Fouling,cleaningand disinfectionhavea critical role in ensuringthe product
quality and operational performanceof food process plant. Cleaning and
disinfectionare increasingly identifiedas essentialprerequisites,whichmustbe
in place before HACCPstudieson microbiologicalhazardscan be implemented.
Foulingis the unwanted accumulationor deposition of material fromthe product
fluidon to product contact surfacesor stagnantareas of equipment.It can be
eitherheat inducedin, for example, a heat exchangeror non-heat inducedin, for
example, a membrane process, accumulationof material in an unhygienic piece
of equipment or growthof a biofilm.The consequencesof fouling can therefore
be primarily operational;for example the depositmay causea significant
deterioration in the hydraulic propertiesof the equipmentleadingto increased
pressuredrops. Heattransfer mayalsobe adverselyaffected,leadingto heat
exchangersbeing unable to maintain theirdesignperformance. Accumulation of
product in stagnant areas of equipment can, depending on the process
conditions, resultin the growthof microorganisms,contaminationof the bulk
product and loss of microbiological quality.
Cleaningis the processby whichthe deposits or accumulatedsoil in the
equipment are removed. The process can vary significantlydepending on
whether the equipmentcan be cleanedin placeor manually.Theremaybe a
number of different stepswithinthe overallprocess but the mainstepsare:
∑ removalor recoveryof bulkproduct fromthe system, generally usingwater
or a productrecoverysystem;
∑ removalof deposits by contactingthemwithdetergentsunderpredetermined
conditions;
∑ finalrinseto removeall tracesof detergentresidues priorto production.
Theprocess of cleaningmayalsoreduce but not eliminatethe numberof
microorganismswithin the system.Disinfection can thenbe appliedafterthe
cleaning processto reducethe numberof microorganismson the productcontact
surfaces to a levelcompatible withthe levelof hygiene requiredfor the product
beingprocessed.
Fouling,cleaningand disinfectionshouldbe consideredas complementary
processes sincetheyeachcan havea significantimpacton eachother.The type
and quantityof foulingwill definethe challenge for the cleaning process and the
optimum strategyfor its removal.The efficiency of the cleaning processwill
strongly influencethe disinfectionstepand,in some cases,failureto clean
effectively will compromise disinfection and the safety of subsequent
production.Failureto clean effectivelymayalso resultin a more rapid build-
up of foulingin the subsequentproduction run.
Effectivemeasurementand monitoringof suchprocesses is criticalfor food
safetyand quality. Withoutmeasurementit is not possible to monitor and
without monitoring,the safetyof the product and processcannotbe controlled
or assured.Monitoring is also essentialin the validation of processes to provide
Monitoringof fouling, cleaning and disinfection in closedprocessplant 573