3.4 Preventionof biofilmformationand biofilmremoval..
Harmfulmicrobesmay enterthe manufacturingprocess and reachthe end-product
in severalways,e.g. through rawmaterials,air in the manufacturingarea,
chemicalsemployed,processsurfacesor factorypersonnel(Lelieveldet al., 2003;
Maukonenet al., 2003).Oncea biofilmis formed,eitheron foodcontact or
environmentalsurfaces,it can be a sourceof contaminationfor foodspassing
through the sameprocessingline. For example,Listeriamonocytogenesis difficult
to removefromthe factoryenvironment once it has becomea part of the house
microbiota (Lunde¬n, 2004).Therefore, it is especiallyimportantfor the persistent
growth of pathogenicand harmfulmicrobesto be preventedin the foodprocessing
line usingall availablemeans(Wirtanen,1995;Josephet al., 2001;Lunde¬n,
2004). In the foodindustry,equipmentdesignand the choiceof surface materials
are importantin fightingmicrobialbiofilmformation. Attentionshould also be
paid to the qualityof additivesand raw materialsas well as the processingwater,
steamand otheradditives, becauseusingpoorqualitymaterialsleadsto the easy
spoiling of the process(Wirtanen& Salo,2004). The aim of microbialcontrolin a
process line is two-fold:to reduceor limitthe numberof microbesin liquidsand
productsand to reduceor limittheiractivityand to preventand controlthe
formationof biofilmson surfaces.At presentthe most efficientmeansfor limiting
the growth of microbesare goodproductionhygiene,the rationalrunningof the
process line, and the well-designeduse of cleaningand decontaminationprocesses
(Alakomiet al., 2002;Wirtanen& Salo,2004). The cleanliness of surfaces,the
trainingof personnel and goodmanufacturingand designpracticesare important
in combatingbiofilmproblemsin the food industry.3.4.1 Hygienicequipment design
Several conferencesand literaturereviews haveshownthat the designof the
equipmentand processline in the foodprocessingand packagingindustry are
important in preventing biofilm formation to improve the process and
productionhygiene(Wimpennyet al., 1999; Wirtanenet al., 1999;Bryers,
2000;Gilbertet al., 2001;Alakomiet al., 2002; Wirtanen,2002;McBainet al.,
2003;Maukonenet al., 2003;Lunde¬n, 2004;Wirtanen& Salo,2004).The most
significantlawsregardingthe foodindustry are the EU directive98/37/EU and
machinestandard EN 1672-2:1997.EN 1672drawsparticular attention to dead
spaces, corners, crevices,cracks,gaskets,seals,valves,fasteners and joints
owingto theirability to harbour microorganismsthat can subsequently endure
adverse/harmful process conditions (Lelieveldet al., 2003;Wirtanen & Salo,
2004).Equipment that causes problems in foodprocessing and packaging
includes slicingand cuttingequipment,fillingand packing machines, conveyors,
plateheat exchangersand tanks withpiping. Thesetypes of equipmentcan cause
contamination throughspoilage microbes and pathogensas theyare difficult to
clean, e.g. the pathogen Listeria monocytogenes is often associated with
harbouragein poorly designedequipment.
58 Handbookof hygiene controlin the foodindustry