by Novozymes)to low molecularpeptidesunderstandardized conditions. The
free aminogroupsformedduringhydrolysisreactwith2,4,6-trinitrobenzene
sulphonicacid (TBNS).The activityis calculatedfromthe opticaldensityphoto
metricallymeasuredat 425 nm employinga calibrationcurve.- The methodLuna no. 2000-10339-01 (Novozymes A/S), wherethe substrate
azocasein(tradename, e.g., SigmaA 2765)is hydrolysed to low molecular
peptides understandardized conditions. Undigested protein is precipitated
withtrichloracetic acid, and the quantityof digestedprotein is determined
by spectrophotometryat 390 nm.
For Savinase,the activityunderdifferenttemperaturesand as a function of the
pH was investigatedat the producer's factory,NovozymesA/S, on a laboratory
scale,applyinghaemoglobinas degradable substrate (datasheet2001-04379-
06.pdf at http://www.novozymes.com)..) The activity curves displayedin this data sheet
expressly refer (accordingtoNovozymes A/S) to the trial conditionsfixedby the
in-houselaboratories.Applying substratesotherthan haemoglobinmay resultin
deviationsfrom this curve.Similartrialswere alsoperformedfor the other
enzymes produced at Novozymes. For the results, please consult the
corresponding datasheets.
32.3.5 Resultsof the laboratorytrials
Enzymetype
Trialsfor removingthe test soilingswiththe enzymespresentedin Table32.1
wereperformedwiththe laboratoryCIP plantdescribedin section32.3.1(Figs
32.3±32.6).Hereby,the enzymeconcentrationof the appliedsolutions(10 L)
werein a first step uniformallyadjustedto 0.05%(relatedto the concentrate
deliveredby the producer)± independentof the indicationsin the datasheets
aboutthe individual enzymeactivity. 8.0 ml of a surfactantmixture were
addedto the dilutedsolutionsused.The pH valuewas adjustedto the optimum
valuegiven by the enzymeproducerwithdilutedNaOH,and by addinga
phosphatebuffer.Startingthe trialsfor scaling-offfoulings withthe enzymatic
solutionswithan acidpretreatment(0.5%HNO 3 , 60 ÎC, 15 min)provedto be
advantageousand preceded, therefore, all of the enzymatictrials.Afteran
extensiveintermediaterinsing(pH controlin the rinsingwater)followedthe
circulationof the enzyme-containing solutionfor a maximumperiodof 45
minutes.Subsequently,the couponswereremovedfromthe plant,rinsedwith
distilledwater,air-driedand photographed.Marginalfoulingresidues,which
are transparentin a wet state andthusnot recognizable, become clearly
apparenton the dry metallicsurface.Aboveall the 4±5m thin foulingunder
a layerknownas the `greyveil',neithersolublein NaOHnor in dilutedacids
± not evenaftercirculationfor severalhours± is easilyrecognizableunder
appropriate lighting in the dry state. Scaling-off trials with 0.5% NaOH
withoutothersupplements in the tap water(17ÎdH)at 65 ÎC servedas a
reference.
526 Handbookof hygiene controlin the foodindustry