decreasein the coagulation periodR 0 from16.0min to 12.5min,theA 10 value
slightlyincreasedfrom14 to 16 mm,and theK 20 value was minimally shortened
from14.0min to 12.5min.The additionof 50 mg of the properase recipeled to
a thickening of the sample(before the additionof the proper rennetenzyme), so
that the subsequentlactodynamographicmeasuringcouldnot be performed.
Themilk had alreadycoagulated before its fillingintothe cuvettes of the
measuring device. Thusthe enzyme, when it comes in highconcentrationinto
the milk,can result into seriousdisordersof the rennet coagulation behaviour.
However, it is unlikelythat contaminationcaused by disordersof the cheese
factory milkcould occurin practice underthe aforementionedorderof magni-
tude.Onereason is that before and afterthe cleaningstep withan enzymatic
solutiona rinsingstepwithwateris performed.The otherreason is that the
(diluted)enzymecontainingsolutionsuffersobvious lossesin activityduringthe
45-minute application.If residues of the solution remainin the system,e.g. over
night,it has to be assumedthat they haveno moreenzyme activitythe day after.
If, as practisedin the fieldtrial in dairy`A' ± a nitricacidpost-rinsingstep is
performed the enzyme activity decreases, according to the datasheetsfor the
enzymeSavinase, immediately to a low,negligiblesize.
The conclusionfromthe laboratorytrialswiththe simulated worst case in the
dairyis that the enzymatic cleaningof the milk heatexchangeris unlikely to
bearadditional,unpredictablerisksin the cheese-makingprocessor the yogurt
manufacture.
32.6 Futuretrends
The processes for enzyme-basedcleaningof equipment and plants in the food
sector,namelycleaningprocesses in the egg and meatprocessingindustry, in ice
creammanufacturingas wellas in the coldmilkdepartmentof the dairycan be
considered as sufficientlytested, and established.In theseareasthe soilings
primarily containnon-denaturedanimalproteins,whichare recognized by many
enzymes and degradedwithout anyproblems. Usingcleaning solutionsat
temperatures of approx. 50 ÎC and in the pH rangeof approximately 9.0 means a
considerablerelief for the environment. Waste waterswiththis pH can be
discharged in a non-treatedstateinto the sewagetreatmentplantas the waste
loadof effluents containedin the wastewatersas wellas possible residues from
the enzymerecipesare considered to be completely biodegradable.Additionally,
at the timeof writingof this chapter,trialswitha considerablysimplified
processare beingperformedin practice using a ready-mixedone-component
recipeinsteadof the moreusualtwo-component recipe,which is addedto the
cleaning solutionimmediately beforeuse via separateddosingdevices. If the
trialsin practice are successful, the enzyme-based cleaning processfor the
aforementioned application areaswill be considerablymore userfriendly than
thosecurrentlyused.Thisconcerns the expenditurefor monitoring measures and
the stock-keepingof chemicalsand,last but not least,the handling.
Enzymatic cleaning in foodprocessing 535