It is a physicallaw that any substance having had contact witha surface
leaves at leasta very thinmolecular layer adheringto the surface. It is a
questionsof physics involving the affinitysurfaceof a surface material to a
substanceor viceversaas to howmuch of a residuehas to be expected. Here
onlyswabtestswithsuitablesolvents or a placebo production withlateranalysis
of traceswill givefurtherinformation.
In normal foodproduction, this wouldbe impractical and not economical. A
simple risk assessment wouldanswer manyquestions. Sucha risk assessment
can be basedupona worstcasestudy calculationas to how muchof a cleaneris
left without rinsing, usingthe fact that 20±40mL/mwill remainon a surface
afterdraining.Considering the use-concentrationand the fillingvolumeof the
equipmentthe maximumpossible concentration of a cleaneror disinfectantin
the finalproduct can be calculated.Evaluatingtoxicitydata and thresholdlevels
shows the impactof the worst casescenarioon a foodproduct.
Ingredientsof cleanersand disinfectantfor the foodindustry do not havea
hightoxicity level.Theirrisk potentialderivesmainly fromtheiracidityor
alkalinity as a concentrate and in use solution. Even this risk decreases
exponentially withfurtherdilution.If thereare any othersubstances that might
be undesirable, suchas nitrates,surfactants and defoamers,theirapplication
should be limited to the absolute required level.
Cleaning is normally not a single stepprocess; alkaline cleaningis often
followedby an acidiccleaningstep and/ordisinfection.Herethe influenceof the
followingstep has to be considered and often this step can provide a safeguard.
A goodexample for this is the eliminationof proteolyticenzymesby using an
oxidisingdisinfectant. Responsible manufacturersof enzymatic cleaners use
onlyproteolytic enzymes that can be easily destroyed by oxidation. This
provides additionalsecurity in the caseof rinsefailures. Lipolytic enzymes on
the marketare muchmore stable and thereis no simplesafeguardingmethod.If
non-ionic surfactants are regarded as a problem, a surfactant-free acidic
disinfectant, following the use of a surfactant-containing cleaner,will further
reduce the minimalresiduepotential.
Plantdesign(hygienicdesign)withregardto smooth surfaces providing
sufficientrinse watercontactsis essential.Further,thereshouldbe no deadlegs
and saggingpipesections. In combinationwitha choiceof adequatecleaners
and disinfectants usedin a properhygiene,sequence will virtuallyeliminate the
last risk of a foodcontamination by properly appliedcleaners.
39.3.5 Identification in caseof accidentsand emergencies, e.g. unidentified
spills, unlabelledcontainers
This last point can be mainly handled in the samefashion as the first point,when
dealing withcontainers having lost theirlabelling. All methodsdescribedmay
be usedto identify the product for proper elimination.
In most cases,as withspills,it is sufficient to find some basicinformation
suchas:
682 Handbookof hygiene controlin the foodindustry