decade. It allows transport to be fast and accurately conditioned. It is expectedto
expand further into central and south Europe in the coming years,also
embracing inlandshippingand controlled atmospherestoragetechnologies.^9
Reportsof temperature abuseon sea-going vessels are related to unconditioned
transports. For instance, temperaturesof 80±90oC have been reported for
unconditionedcontainersthat are on top positionon the boat and sail throughthe
tropics. These extremely high temperatureshavedetrimental effects on the
foodstuffspresentin the hot container.
25.6 Avoiding cross-contamination.
Cross-contamination can be avoided by takingthe correct precautions.Some
loadsshould not be transported simultaneously or should be wellseparated by a
barrier, suchas palletsleevesor palletwraps. Alternatively, transportunits could
be cleanedprior to and aftertransportwitha highrisk for contamination:liquids,
bulkgoodsand hungcarcasses.In the past cross-contaminationproblems have
arisenwithreturnfreightsand wooden pallets.
Returnlogisticssuchas returnable poly(ethyleneterephthalate)(PET)bottles
forma potentialcontamination hazardin retailtrucks.Thesetrucksserve several
shopsfromone distribution centreand deliverfoodstuffsto the shopsand pick-
up returnablePETbottles. Theseusedbottles contain sugar-rich residues and are
perfectgrowthmedia for microorganisms.A limited amountof bottlesare
misused by consumers and containresidues of motoroil, pesticides,urine,etc.
Sincethesebottlesdo not all havetheirscrew capstightened,a palletrackof
thesereturned bottlesformsa dripping stack.The fluidswill drip on the floorof
the truckand causecross-contaminationto otherloads. Someincidents have
beenreportedwithreturned bottlesin the past. Nowadays,thesebottles are
collected in big bagsor closable cratesin the supermarkets.These bagsor crates
are closed,mountedon pallettrolleysand transported without hygiene problems.
Anotherexample of a troublesomereturnfreight is spoiltmeat.Freshmeat
that has reachedits best-before date in the shopneedsto be collected separately
and destroyed at an approved facility. Somesupermarket chainsalsouse the
normaltransporttrucksto returnthis loadfromthe shopsto the distribution
centres. In cases where the spoiltmeatwas packed undermodified atmospheres,
thereis no problem; otherwise the spoiltmeatshouldbe packedair-tight before
returntrucking. Emptyplasticcratesformanother largereturn loadin retail
transports. Thisreturnloadis often non-cooled and can causetemperature
controlproblems when combinedwithloads of chilled foodproducts.
The hygieneof woodenpalletshas beenheavily debated,as a result of the
microbial florafoundin otherwooden articles, suchas cutting boards.10,11Based
on the differences in structureand cleanability it appears to be likely that plastic
palletswill be morehygienicthan woodenpallets. Hence,on the internetseveral
palletsuppliers promote hygienicplasticpallets that are more cleanablethan
wooden pallets.^12 However, fromthe availablescientific literatureit cannotbe
Improvinghygienein foodtransportation 403