The ongoingoperation of hygieneGMPs can be monitoredfirstlyby visual
audits. Thesemaybe undertaken within a timeframe suchthat if faultsare
found,controlmeasurescan be implementedimmediately.For the hygiene of
surfaces,rapidmethodsare also availablethat can detectthe presenceof soiling
(food residues and microorganisms), beyondvisiblecleanliness, in a timeframe
(approximately <10 min)allowing processcontrol.Suchmethodsincludethe
detectionof specificchemicalmarkers of soiling, e.g. adenosine triphosphate
(ATP) or physicalparameters suchas pressuredropsor heattransferrates.
Verification of the success of hygiene GMPs is usually undertaken by
microbiological sampling. Samples can be analysedfor markers of overall
hygiene (totalviable count), indicators of poorhygienepractice (Enterobacter-
iaceae or coliforms)or specific pathogens.Resultsare availablewithinan
extendedtimeframe(24±48hoursor longer) suchthat processcontrolis not
possible. Verification resultsare thus usedto assess the overallperformance of
the GMP, and can be trend analysedovertimeperiodsto ensure that the GMPis
effectiveand/orcan be improved.
Finally, if problems do occur,troubleshooting exercisescan be undertakento
identify any failingsin the system. Modernmicrobiological approaches using
genetic fingerprinting techniques nowallowa much morein-depthassessment
of the microbial ecologyof foodmanufacturing plantsthan was hithertopossible
and are leadingto enhanced detection and control of environmental microbial
niches.
308 Part III