32.2 Enzyme-basedcleaningprocedures
32.2.1 Enzyme-basedcleaning of the coldmilkarea
On the way fromthe producer to the consumer,milkin cartonsor bottles, or in
milkproducts suchas yogurtor cheese, passesthroughmanystations,where it is
exposed to contamination from microorganisms and also to residues of
precedingproduct batches.
Under the presumptionof sufficient udderhygiene(cleaningand disinfecting
the udderand the separation of the foremilk)the firstpossible contamination
source for milkis the milkproduction plant,including the coolingcontainer on
holding. Thisarea is underthe responsibilityof the production holding.A daily
clean with conventionalalkaline chemicals (andwithacidchemicals at least
onceper week), is performed as wellas additional, regulardisinfectionswith
boiling water.In newer milkproductionholdings, the use of a two-phase air-
fluid flow withextremelyhighflowturbulence and correspondingly highwall
shearstressin the pipelines, allowedconsiderablereductionsin the volumeof
cleaningsolutionsusedduring cleaningby up to 70%(Reinemannet al., 1998,
Grasshoffand Reinemann, 1993).
The milk is pumpedfromthe receivingcontainerinto the milktanker. From
this pointof timethe acceptingdairyis responsible for its hygiene.The milk
tanker, of highlycomplexgeometricconstruction withinlettube,pumps,de-
aerator, quantitymeasurement,and automatic sampling devices, bearsthe risk
that milk of irreproachablequality from the production holdingmay be
contaminatedby infectedresidues froma preceding milkbatch.To exclude this
contamination risk fromremainingmilkresiduesit is vitalthat the milktankeris
thoroughlycleaned.
In the dairy,the milkis filledfromthe milktankerinto a raw milkreceiving
tank, wherebymilkis oncemorein touchwithinlettubes, pumps, collecting
devices, pipelines,and tankwalls, whichmaybe contaminatedby residues of
precedingbatches.
Afterthe subsequentheattreatmentof milk(pasteurization,ultraheating),
furtherprocesses follow,including cooling,storageand fillingof consumer
milk,cheese making and ice creamproduction. All theseareas distinguish
themselves by a similar structureof soiling (in this contextproductresidues are
consideredas soiling),whichcontainmoreor less originalproteins, fat, lactose,
milksaltsand traceelements. For this reason theyare an idealsubstrate for ±
undesired ± microorganisms,and must be regularly and carefullyremoved. The
conventionalway,whichis usuallysuccessful, is to removetheseresiduesvia
installed cleaning-in-place (CIP) plants using alkaline and acid chemical
formulae.
As enzymeshavebeenregularlyusedin the detergentindustry sincethe
1960sfor textilecleaning, efforts are alwaysbeingmadeto enlargethe applica-
tion fields of enzyme-basedcleaningagents.In October 1994,EcolabNorth
America (www.ecolab.com) presentedan enzyme-basedcleaningmethodunder
the name `Paradigm' that has beenusedworldwidein the dairy,ice cream,
518 Handbookof hygiene controlin the foodindustry