A quickmonitoringdeviceis the application of ATPas measurementfor
remainingmicroorganismsand/or organicsubstances. The principle is basedon
the fact that everyorganiccell contains ATPas energycarrier.The reactionof
the enzymeluciferasewithATPresultsin the emission of lightthat can be
measuredby a specificlight-measuring device.The morelightis emitted the
more ATPwas presentand the morethe surfaceor liquidwas contaminatedwith
microorganismsor organic matter. It is evenpossible to differentiatebetween
microbial and organic ATP.A disadvantageof this methodis that the detection
limitis relatively high. The minimum concentration of microorganisms is
approx. 10^3 ±10^4 cfu mlˇ^1 (Mooreet al., 2001)beforethis methodbecomes
reliable whereas this amount is already crossingthe limitof levels of con-
tamination.Thus, measuring ATP is suitable for a quick inventoryof the
cleanlinessof equipment or rinsing water. Themethodis not applicable to
determinethe antimicrobialactivity of disinfecting agents.
A differentway of optimisingcleaning and disinfectingprocessingconcerns
the combinationof databasesand predictive modelling. NIZO PremiaTMis an
example that combinesresearch knowledgewithpredictive modelling. It is a
software platform that is usedfor optimisationof product propertiesor process
performance. For example, fouling is mainlycaused by denaturation of proteins
and precipitation of minerals. The denaturation processof -lactoglobulin(an
importantwhey protein)can be described as a consecutiveset of reactions (de
Jong,1996).Thisknowledge can be usedto predictthe fouling behaviour in heat
exchangersof differentdairy-typeproducts. By predictingthe amount of fouling
produced, the optimum runningtimefor heat exchangerscan be determined. In
addition the compositionof the fouling layeris known which makesit possible
to choosethe right cleaning procedures (cleaning agents,temperature,etc.).
After optimisationwithNIZOPremiait appearedpossible to reduce the amount
of foulingby 50±80%, resultingin longer running timesand higherprocess
efficiency (de Jong et al., 2002). Another possibility is using predictive
modellingfor the designof newprocessinglines,makingthe effectsvisible
concerningfoulingand product properties.A typical example is the develop-
ment of a newtypeof evaporator at a Dutchdairy company wherethe use of
NIZO Premia resultedin 70%less energy use comparedwithstandard designed
evaporators(Visserset al., 2002).
Thus, predictivemodelling is a powerful tool to analyseand optimisecritical
processes withinthe foodindustry.
4.4 Types of pathogenresponse....
Whenapplying chemical disinfectantsin a processor on process equipmentit is
importantto knowhowmicroorganisms/pathogens mayrespond.Likeevery
other organism, microorganisms protect themselves against all kinds of
influence from the environment. Some of the protection mechanisms are
intrinsic (naturalproperty) but othersare acquired (mutationor acquisitionof
82 Handbookof hygiene controlin the foodindustry