removed,thusa moreefficientcleaningprocessis obtained(Gibsonet al.,
1999).However,thereis a limit, as too muchmechanicalaction (e.g.by using
metalscrubbingdevices)maycausedamage to the cleanedobject/surface.
The final effectdepends on the right combinationof the conditionsdiscussed.
However, it remains possible to choosefor differentcombinations of conditions
as longas `the sum' of the conditions will be the same,e.g. a reduction of the
concentrationcan be compensated by an increase in timeor mechanicalaction
(Krop, 1990).
4.3.3 Influenceof neutralisingcomponents
Prior to disinfecting,the equipmentor surfaceto be treatedshouldnot contain
any componentsthat can inactivate the disinfectant. Organicmatter (e.g.food
residues, milkstone,blood) are wellknown for theirneutralisingeffect.In
general theseorganicmaterials interfere by reactingwiththe biocide, leavinga
reduced concentrationof antimicrobialagentfor attack on microorganisms. In
addition to organicmaterials, surface-activeagents and metalions can act as an
interferingsubstrate (Russell, 1999a).
4.3.4 Monitoring
As shown, a lot of characteristics concerningthe applicationof disinfectants and
the inactivation of microorganisms are known. But knowledge does not
guarantee appropriatecontrol of the process.Thorough analysisof availabledata
is necessary to makethe rightdecision withregardof typeof disinfectant,
process conditionsand required effect.Monitoringdevices to analyse cleaning
and disinfectionprocesses,and databasescontaininginactivationkineticsof
relevant microorganismsin combinationwithpredictiveknowledge can be a
great helpin optimisingrelevant processes.
Withregard to monitoring,OPTICIP,a monitoringdeviceto makeand
optimise cleaning-in-place (CIP)procedures can be applied(vanAsselt and te
Giffel, 2002).A typicalcleaningprocedureof an evaporator before and after
optimisationis shownin Fig. 4.1. The system monitorsthe removalof organic
and inorganic fouling off-linein combinationwiththe in-linemeasurementof
parameterssuchas temperature,flow,conductivityand valve settings.The
turbidityof the cleaning solution is a measure for the removalof organic fouling.
The calciumconcentrationis a measure for the removalof inorganicfouling.
Conductivitymeasurement is usedfor separationof the variouscleaningphases
and givesan indication of the concentrationof the cleaning solution used.Sharp
slopes between subsequentphasesindicatethat rinsing and cleaningphasesare
properly separated(vanAsseltet al., 2002).Moresimplifiedsystems are also
available. Johnson-Diversey introduced `Shurlogger', a real-time CIP
monitoringsystembasedon flow,temperature and conductance (Dodd,2003).
However, the foulingremovalis not taken into account. Therefore,this system
gives less detailedanalysescomparedto OPTICIP.
80 Handbookof hygiene controlin the foodindustry