In spiteof its importance,cleaning couldbe furtherimproved in manu-
facturing, retailand foodservice (Gibsonet al., 1999;Griffithet al., 2002;
Sagooet al., 2003).
36.1.1 Cleanliness, microbial growth/survival and cross-contamination
As indicatedabove,organicmatterderivedfromfoodsor food-relatedresidues
can be associatedwith microorganisms.Whensupplied withnutrients and the
correct conditions these microorganismscan surviveand/ormultiply. The ability
of bothfoodspoilage and pathogenic organismsto attach to a widevarietyof
materials usedwithinthe foodindustry,is welldocumented(Cunliffeet al.,
1999).Following attachment,some bacteria can exhibita variety of physio-
logicaland genetic responsesto a rangeof environmental stresses, enabling
themto survive in less thanidealconditions(Humphreyet al., 1995).Once
attached,some microroganismscan formbiofilms (microorganisms plusasso-
ciated organic matrix), which can be even more difficultto remove with
increased resistance to disinfectants and sanitisers (Gilbert et al., 1990).
Monitoringcleaning programmes can therefore involvelooking for the presence
of microorganisms,organic residues or both.
Unlike bacteria,yeastsand moulds, whichcan growin, or on, soiledequip-
ment and environmentalsurfaces, virusesare obligate intracellularparasites, i.e.
onlygrowin otherlivingcells.However, somecan survivewelloutside their
hosts and persist in the environmentfor daysor months.Cleaning and good
personalhygieneare essentialin preventingthe spreadof viraldiseases.
Cross-contamination(definedas the processof contaminatinga previously
uncontaminatedfoodsurface or food)is of particular concernfor those micro-
organismsthat havea low minimalinfectious dose(e.g.EscherichiacoliO157,
Norovirus).Cross-contamination can occurdirectly,fromcontaminatedto un-
contaminated,e.g. raw ready to eat, or indirectly.Indirect cross-contamination
can involvea single eventor be muchmorecomplex (see Fig. 36.2),involvinga
complex web of stepsinvolving hands,equipment and surfaces.Within the food
service environment giventhe frequency withwhichhandstouch contaminated
Fig. 36.2 Potentialfor cross-contaminationin an abattoir.590 Handbookof hygiene controlin the foodindustry