CODEOFPRACTICEFORTHEPREVENTIONANDREDUCTIONOFMYCOTOXINCONTAMINATIONINCEREALS

CAC/RCP51-2003

Adoptedin2003.

Amendment:2014,2017.Revision:2016.

CAC/RCP51-2003

PAGE

INTRODUCTION

Toxigenicfungiareprevalentinregionsinclimaticzoneswhichallowforsmallandlargescalecerealgrainproduction.Althoughthespeciesandstrainsmaydifferamonggrain-producingregions,thesefungiarepresentinsoils,inwildhostplantspecies,intheresiduesofcultivatedcropsandstoredgrainsandinthedustindryingand/orstoragefacilities.Thefungiareassociatedwithbothpre-harvestandpostharvestmycotoxincontaminationincereals.

Theseverityofpre-harvestfungalpropagationishighlydependentuponweatherconditionsvaryinggreatlyfromyeartoyearingrain-producingregions.Theseverityofpre-harvestinfectionandpropagationoftoxigenicfungicanalsovarywiththedegreeofdamagecausedbyinsectsandothernon-toxigenicfungi.Becauseofthesefactors,mycotoxinconcentrationsobservedingrainsatharvestvarywidelyfromyeartoyear.Reliablepreventionofpre-harvestfungalinfectionhasbeenproventobeelusive,evenwithapplicationofgoodagriculturalpractices(GAP)andcommerciallyavailablefungicides.CerealbreedinghasresultedinonlymodestgainsingeneticresistancetotheFusariumearblight(Fusariumheadblight)ofcerealsincultivarswithacceptablequality,yieldandtolerancetootherimportantcerealdiseases.

Theseverityofpost-harvestfungalinfectionandpropagationduringprolongedperiodsofgrainstoragecanbemanagedmorepredictablythroughGAPandgoodmanufacturingpractices(GMP)thatensurethatmoisturelevelsinstoredgrainremainbelowlevelsthatareconducivetogerminationofsporesofcommonpost-harvestfungalspeciesspecifictotheenvironmentalconditionspresentintheregion.However,researchhasconfirmedthatsporesofsuchspeciesareubiquitousinsoils,equipment,andstoragestructuresdespitediligentcleaning.Consequently,germinationofthesporesofthemycotoxigenicspeciescanoccurwithincertaintemperaturerangesifevenasmallamountofstoredgraindevelopselevatedmoisturelevelsfromexposuretoprecipitationorinsectinfestation.Thesizeanddesignoflargegrainstoragestructuresandthelimitedaccesstotechnologyoftenmakeprecisemonitoringofmoistureandtemperatureinstoredgrainextremelydifficultorotherwiseimpractical.

Riskofpost-harvestfungalinfectionandproductionofmycotoxinsinstoredgrainincreaseswiththedurationofstorage.However,longtermstorage,generallythroughoutanentirecropyearorforevenlongerperiods,mayberequireddependingonthegrainneedsofthespecificproductionregionwherethecommodityisbeingstored.Thismaybeduetoreasonsoffoodsecurityandthecontinuousinputintostorageofnecessarycerealgrainsfordirectconsumption,processingand/oranimalfeed.

Thecompletepreventionofdisseminationbypre-harvestandpost-harvesttoxigenicfungalspeciesisnotpracticallyachievable,evenwhenGAPandGMParefollowed.Therefore,theintermittentpresenceofcertainmycotoxinsincerealgrainsdestinedforhumanfoodandanimalfeeduseistobeexpected.Thusdiligentmonitoringofcerealgrainsinthefieldandduringstorageforindicationsofthevariousconditionsthatpromotefungalcontaminationandmycotoxinaccumulationisimperativetodeterminedispositionofthecommodity.

ThisCodeofPracticeprovidescurrentandrelevantinformationforallcountriestoconsiderintheireffortstopreventandreducemycotoxincontaminationincerealgrains,grain-derivedfoodsandanimalfeeds.InorderforthisCodeofPracticetobeeffective,itwillbenecessaryfornationalauthorities,producers,marketers,andprocessorsineachcountrytoconsiderthegeneralprinciplesandexamplesofGAPandGMPprovidedintheCode,takingintoaccounttheirlocalcrops,climate,andagronomicpracticestoenableandfacilitateadoptionofthesepracticeswhererelevantandfeasible.ThisCodeofPracticeisexpectedtoapplytoallcerealgrainsandcerealproductsrelevanttohumandietaryintakeandhealthaswellasinternationaltrade.

ItisimportantforgrainproducerstorealisethatGAP,includingpostharvest,storage,handlingprocedures,representtheprimarylineofdefenceagainstcontaminationofcerealswithmycotoxins,followedbytheimplementationofGMPduringthehandling,storage,processinganddistributionofcerealsforfoodandanimalfeed.ProcessingindustriesalsohavearoletoimplementGMPwhererequired,mainlyduringgrainsorting,cleaningandprocessing.

CerealgrainproducersshouldbetrainedtofollowGAPandmaintainacloserelationshipwithagriculturaladvisors,extensionservicesandnationalauthoritiestoobtaininformationandadviceregardingthechoiceofappropriatecerealgraincultivarsandplantprotectionproductssuitableforuseintheirrespectiveproductionregionssoastoreduceincidenceandlevelsofmycotoxins.

ThisCodeofPracticecontainsgeneralprinciplesforthereductionofvariousmycotoxinsincereals.Fortheeducationofproducers,handlersandprocessors,andprovidinginformationontestingtorelevantparties,thefollowingshouldbeobserved:

Nationalauthoritiesand/orotherorganisationsshouldeducateproducersregardingtheenvironmentalfactorsthatfavourinfectionandgrowthoftoxigenicfungi,andmycotoxinproductionincerealcropsatthefarmlevel.Emphasisshouldbeplacedonthefactthattheplanting,pre-harvestandpostharveststrategiesforaparticularcropwilldependontheclimaticconditionsofthatparticularregionandyear,takingintoaccountthelocalcrops,andtraditionalproductionmethodsforthatparticularcountryorregion.Nationalauthoritiesshouldsupportscientificresearchonmethodsandtechniquestopreventfungalgrowthinthefieldandduringharvestandstorage.

Inordertoavoidunduedisruptionofgrainshipmentoperations,validatedanalyticalmethodsandassociatedsamplingplansshouldbeutilisedbyproducers/handlers/processorstoquicklydeterminemycotoxinlevels.Theproperimplementationofsamplingplansanduseofanysuchanalyticalmethodsortoolsarecriticaltotheirprovisionofaccurateinformationanddata.Thiswillrequireadequateresourcesandtrainingtoensurethatsamplingplansarefollowedandtestprocedurescanbeproperlyperformed.Proceduresshouldbeinplacetoproperlyhandle,throughsegregation,reconditioning,recallordiversion,cerealcropsthatmayposeathreattohumanand/oranimalhealth.

ThisCodeforthepreventionandreductionofmycotoxinsincerealgrainsandgrain-derivedfoodsandfeedsrecommendspracticesbasedonGAPandGMPandaregenerallyconsistentwithHazardAnalysisCriticalControlPoints(HACCP)principleswhichareincorporatedintocurrentfoodsafetypracticesandcertificationschemesnowinglobaluseinproduction,storage,handling,transportation,processing,distributionandtrade.TheimplementationofHACCPprincipleswillminimisemycotoxincontaminationthroughapplicationsofpreventivecontrolmeasurestotheextentfeasible,mainlyduringstorageandprocessingofcereals.

I.RECOMMENDEDPRACTICESBASEDONGOODAGRICULTURALPRACTICES(GAP)ANDGOODMANUFACTURINGPRACTICES(GMP)

Plantingandcroprotation

Considerdevelopingandmaintaininganappropriatecroprotation/sequencescheduletoavoidplantingthesamecropinthesamefield,fortwoconsecutiveseasons.Thiscanhelptoreducetheinoculuminthefieldwhichmayoriginatefromdebrisremainingafterharvestthatharbourstoxigenicfungalspores.Somecropshavebeenfoundtobeparticularlysusceptibletocertainspeciesoftoxigenicfungiandtheuseinrotationwitheachothershouldbeevaluated.Table1showsthemostsusceptiblecropstotoxigenicfungiandthemycotoxinsthatcanbeproduced.Someofthesecropsareinfectedafterharvestandtheresultingseedscancarrytoxigenicfungalspores.Cropsoflowsusceptibilitytotoxigenicfungisuchasclover,alfalfaandotherlegumescanbeusedinrotationtoreducetheinoculainthefield.WheatandmaizehavebeenfoundtobeparticularlysusceptibletoFusariumspeciesandtheyshouldnotbeusedatveryclosepositionsinrotationwitheachother,ifpossible.Whenusedinthesamerotation,inclusionofsoybeans,oilseeds,pulsesandforagecropsmayreducetheincidenceandseverityofpre-harvestinfection.

Table1.Susceptiblerotationcropstotoxigenicfungiassociatedwithproductionofmycotoxins(notexhaustive)

Crops

Fungi

PotentialofMycotoxins

Peanuts

Aspergillusflavus

A.parasiticus

A.nomius

Andotherrelatedspecies

Aflatoxins

Maize

A.flavus

A.parasiticus

andotherrelatedspecies

Aflatoxins

Fusariumgraminearum

F.culmorum

deoxynivalenol,nivalenol,zearalenone

F.verticillioides

F.proliferatum

fumonisins

Sorghum

FusariumgraminearumFusariumspp.

deoxynivalenol,nivalenol,zearalenoneanddiacetoxyscirpenol

Crops

Fungi

PotentialofMycotoxins

Alternariaspp.

alternariol,alternariolmethylether,tenuazonicacidandaltenuene

F.verticillioides

F.proliferatum

fumonisins

A.flavus

A.parasiticus

A.sectionFlavi

Aflatoxins

P.verrucosum

A.ochraceusandrelatedspecies

A.carbonarius

A.niger

ochratoxinA

Clavicepspurpurea

C.Africana

C.sorghiandrelatedspecies

ergotalkaloids

A.versicolor

sterigmatocystin

Wheat

Alternariaspp.

alternariol,alternariolmethylether,tenuazonicacid

F.graminearum

F.culmorum

F.asiaticum

deoxynivalenol,nivalenol,zearalenone

Barley

F.graminearum

F.culmorum

F.asiaticum

deoxynivalenol,nivalenol,zearalenone

Oats

F.graminearum

F.culmorum

F.langsethii

deoxynivalenol,nivalenol,zearalenone,T-2andHT-2toxin

Rye

F.graminearumClavicepspurpurea

deoxynivalenol,ergotalkaloids

Cotton

A.flavus

A.parasticus

Aflatoxins

Millet

F.graminearum

Deoxynivalenol

Triticale

F.graminearum

Deoxynivalenol

Tillageandpreparationforseeding(planting)

Whenpossibleandpractical,usetoxigenicfungifreecertifiedseedsandpreparetheseedbedforeachnewcropbyplowingunderorbydestroyingorremovingoldseedheads,stalks,andotherdebristhatmayhaveserved,ormaypotentiallyserveassubstratesforthegrowthofmycotoxinproducingfungi.However,tillingmaynotbeappropriatewithrespecttoothereconomicandenvironmentalbenefits,suchasmoistureconservation,maintenanceofsoilorganicmatter,reducederosion,andlowerfuelandwateruse,henceitscostsandbenefitsshouldbeconsideredpriortoapplication.

Utilisetheresultsofsoilteststodetermineifthereisaneedtoapplyfertilizerand/orsoilconditionerstoassureadequatesoilpHandplantnutritiontoavoidplantstress,especiallyduringseeddevelopmentstageofcropgrowth.

Whenavailable,growvarieties(cultivars)thatweredevelopedandselectedfortheirtraitsofprovidingatleastpartialresistancetobothnon-toxigenicandtoxigenicfungiandinsectpestsandforlowermycotoxinaccumulation.Itisimportanttoplantonlythosevarietiesrecommendedforuseinaparticularareaofacountrybyvirtueoftheirspecificphysiologicalandagronomictraits.

Asfaraspractical,cropplantingshouldbetimedtoavoidhightemperatureanddroughtstressduringtheperiodofseeddevelopmentandmaturation.Predictivemodels,whenavailable,couldbeusedasatooltoplanforthebestplantingperiod.

Ensureappropriatedensityofplantingbymaintainingtherecommendedrowandintra-plantspacingforthespecies/varietiesgrown.Informationconcerningplant-spacingmaybeprovidedbyseedcompanies,nationalauthoritiesorextensionservices.

Pre-harvest

Wherepossible,minimiseinsectdamageandfungalinfectioninthevicinityofthecropbyproperuseofapprovedpesticidesandotherappropriatepracticeswithinanintegratedpestmanagementprogramme.Predictiveweathermodelscouldbeusedtoplanthebestapplicationtimingandmodeofpesticideapplication.

Ascertainweedspeciescanactashostsfortoxigenicfungithatcanincreaseplantstressduetocompetitionofweedspeciesduringcropdevelopment,itisimportanttocontrolweedsinthecropbyusingmechanicalmethods,registeredherbicidesorothersafeandsuitableweederadicationpracticesutilisinganintegratedpestmanagementprogramme.

Minimisemechanicaldamagetoplantsduringcultivation,irrigationandpestmanagementpractices.Minimiselodgingofplantstopreventcontactoftheaerialpartsoftheplantswithsoil,particularlyatthefloweringstageofthecrop.Soilandsoilwateraresourcesofinoculum(spores)oftoxigenicfungalspecies.

Ifirrigationisused,ensurethatitisappliedevenlyandthatallplantsinthefieldhaveanadequatesupplyofwater.Irrigationisavaluablemethodofreducingplantstressinsomegrowingsituations.Excessprecipitationduringanthesis(flowering)makesconditionsfavourablefordisseminationandinfectionbyFusariumspp.;thusirrigationduringanthesisandduringtheripeningofthecrops,specificallywheat,barley,andrye,shouldbeavoided.

Plantoharvestgrainatlowmoisturecontentandfullmaturity,unlessallowingthecroptocontinuetofullmaturitywouldsubjectittoextremeheat,rainfallordroughtconditions.DelayedharvestofgrainalreadyinfectedbyFusariumspeciesmaycauseanincreaseinthemycotoxincontentofthecrop.Modelscouldbeusedtopredictthemycotoxinproductionbasedonenvironmentalconditions,suchasclimateconditionsandagriculturalproductionconditions,beingaguidetotimelymonitoringandsurveyingofmycotoxinlevels.

Ifmechanicaldryingequipmentisavailable,earlierharvestmaybehelpfulinlimitingmycotoxinproductionduringthefinalstagesofcropmaturation.Itisimportanttouseproperdryingtechniquesinordertoavoidcontaminationbycontaminantsgeneratedbyimproperdryingtechniquessuchaspolycyclicaromatichydrocarbons(PAH)1anddioxins2.

Beforeharvestensurethatallequipment,tobeusedforharvesting,drying,cleaningandstorageofcrops,isinagoodworkingorderandcleanedofcropresidues,grainanddustasmuchaspossible.Abreakdownofequipmentduringthiscriticalperiodmaycausegrainqualitylossesandenhancemycotoxinformation.Keepimportantsparepartsavailableonthefarmtominimisetimelossfromrepairs.Makesurethattheequipmentneededformoisturecontentmeasurementsisavailableandcalibrated.

Harvest

Containersandconveyances(e.g.wagons,trucks)tobeusedforcollectingandtransportingtheharvestedgrainfromthefieldtodryingfacilities,andtostoragefacilitiesafterdrying,shouldbeclean,dryandfreeofcropresidues,oldgrain,graindust,insectsandvisiblefungalgrowthbeforeuseandre-use.

Methodsofharvestandequipmentusedvarywidelyamonggrain-producingcountries.Cuttingofgrainintoswathspriortocombiningorthreshingbyothermeanscancontributetocontactwiththesoilandexposuretofungalspores.Asfaraspossible,avoidmechanicaldamagetothegrainandavoidcontactwithsoilduringtheharvestingoperation.Stepsshouldbetakentominimisethespreadofinfectedseedheads,chaff,stalks,anddebris(cropresidues)ontothegroundwheresporesandotherfungalstructuresmaysurviveandserveasinoculaforfuturecrops.Mechanisedharvestmethodssuchastheuseofcombinesresultinlargeamountsofthecropresiduebeingleftinthefield.Wherecroprotation/sequenceandrelatedtillagepracticespermit,itispreferabletoincorporatethiscropresidueintothesoilbyploughingorcultivationbyothermeans.

Duringharvestingoperation,themoisturecontentshouldbedeterminedinseveralspotsofeachloadoftheharvestedgrainsincethemoisturecontentmayvaryconsiderablywithinthesamefield.Asfaraspossible,avoidharvestinggrainwithhighmoisturecontentduetoprecipitationormorningdeworduringlateafternoonasittakesalongertimetodry.Ifpossible,whenpre-harvestmonitoringorsurveyingofgrainshowsafieldashavingahigherFusariuminfectionrate,harvestandstoregrainfromsuchfield(s)separatelyfromthosefieldswithalowerinfectionrate.

1 CodeofPracticefortheReductionofContaminationofFoodwithPolycyclicAromaticHydrocarbons(PAH)fromSmokingandDirectDryingProcesses(CAC/RCP68-2009)

2 CodeofPracticeforthePreventionandReductionofDioxinandDioxin-likePCBContaminationinFoodandFeeds

(CAC/RCP62-2006)

Harvestedgrainthathasnotbeendriedtoasafestoragemoisturelevelshouldnotbestoredortransportedinbins,wagonsortrucksforprolongedperiodsoftime.Transittimeformovementfromfieldtodryingfacilityshouldbeminimisedunlessthegrainisalreadyatacceptablestoragemoisturelevelsbeforeharvest.Whennecessaryitisrecommendedthatthetrucksandcontainersbeopened,toincreaseaerationandminimisethecondensationeffects.

Dryingandcleaningbeforestorage

Avoidpiling,heaping,orbinstorageofhigh-moisture,freshlyharvestedcommoditiesformorethanafewhourspriortodryingorthreshingtolessentheriskoffungalgrowth.Ifitisnotpossibletodrythecommoditiesimmediately,aeratethembyforcedaircirculation.

Whennecessarypre-cleaningbeforedryingcanbecarriedouttoremovelargeamountsofstraworotherplantmaterialthatcancarrymouldormouldspores.Winnowingandsortingmethodscanbeutilisedtocleanthegrain.Ifcleaningequipmentisavailable,itisadvantageoustomechanicallycleangraintoremoveforeignmaterial,seedsofotherplantspecies,andcropresiduespriortotransfertostoragestructures.Howeveritisimportantthatthegrainisnotdamagedduringtheprocedure.

Itisveryimportanttoensurethatmoisturelevelsinharvestedgrainsarelowenoughtopermitsafestorageforevenrelativelyshortperiodsoftimerangingfromafewdaystoafewmonths.Amaximumlevelof15%moistureisgenerallyconsideredtobelowenoughtopreventfurthergrowthofpre-harvesttoxigenicfungiandgerminationofsporesoffungithattypicallyinfectgrainandproducemycotoxinsduringstorage,suchasPenicillium.

Freshlyharvestedcerealsshouldbedriedimmediatelyinsuchamannerthatdamagetothegrainisminimisedandmoisturelevelsarelowerthanthoseneededforfungalgrowthduringstorage.Itispreferabletoreducegrainmoisturecontenttoanacceptablelevelpriortotransfertostoragebinsandotherstoragestructures.Ifitisnotpossibletodrythecommoditiesimmediately,aeratethembyforcedaircirculationandkeeptheperiodbeforedryingasshortaspossible.Mechanicaldryingispreferred.Flatbedandre-circulatingbatchdriersareadequateforsmallscaleoperationswhileusingacontinuousflow-dryerispreferredforlargescaledryingpriortolongstorageperiods.Grainsshouldnotbeexcessivelydriedorsubjectedtoexcessivelyhighdryingtemperaturesinordertopreservenutritionalqualityandsuitabilityformillingorotherprocessing.Theuseofgooddryingpracticesisessentialtoavoidcontaminantsgeneratedbytheprocess.Avoidaccumulatingtoomuchgraininthepre-drierstorageor“wettank”,especiallywhenfieldconditionsarewarm.Storegrainsonlyenoughthatcanbeeasilydriedinasuitabletimeperiod.

Ifmechanicalmeansofdryingarenotavailable,sunandopenairdryingshouldbedoneoncleansurfaces;totheextentpossible.Grainsshouldbeprotectedfromrain,dew,soil,pests,birddroppingsandothersourcesofcontaminationduringthisprocess.Formoreevenandfasterdrying,mixorstirgrainsfrequentlyinthinlayers.

Afterdrying,cerealgrainshouldbecleanedtoremovedamagedandimmaturekernelsandotherforeignmatter.Kernelscontainingsymptomlessinfectionscannotberemovedbystandardcleaningmethods.Seedcleaningprocedures,suchasgravitytablesandopticalsorting,mayremovebrokenkernelsthataresusceptibletoinfection.

Storageafterdryingandcleaning

Itisimportantthatbins,silos,shedsandotherbuildingsintendedforgrainstoragearedry,well-ventedstructuresthatprovideprotectionfromrain,snow,groundwater,moisturecondensation,andtheentryofrodents,birdsandinsectsthatcannotonlycontaminategrain,butdamagegrainkernelstorenderthemmoresusceptibletomouldinfection.Ideally,storagestructuresshouldbedesignedsoastominimisewidefluctuationsinthetemperatureofthestoredgrain.

Storagefacilitiesshouldbecleanedpriortoreceivinggraintoremovedust,fungalspores,grain,cropresidues,animalandinsectexcreta,soil,insects,foreignmaterialsuchasstones,metalandbrokenglass,andothersourceofcontamination.

Forbaggedcommodities,ensurethatbagsareclean,dryandstackedonpalletsorincorporateawaterimpermeablelayerbetweenthebagsandthefloor.Thebagsshouldfacilitateaerationandbemadeofnon-toxicfood-gradematerialsthatdonotattractinsectsorrodentsandaresufficientlystrongtoresiststorageforlongerperiods.

Determinemoisturecontentofthelot,andifnecessary,drythecroptothemoisturecontentrecommendedforstorage.Fungalgrowthingrainiscloselyrelatedwithwateractivity(aw),commonlydefinedinfoodsasthewaterthatisnotboundtofoodmolecules(suchasmilledgrainproducts)thatcansupportthegrowthofbacteria,yeasts,andfungi.Althoughtheappropriatemoisturecontentforfungalgrowthonvariousgrainsisdifferent,themaximumawtoavoidfungalgrowthisbasicallythesame.Itisrecognisedthatfungalgrowthisinhibitedatawoflessthan0.70.Theappropriatelevelofmoisturecontentofgrainshouldbedeterminedbasedoncerealvariety,kernelsize,grainquality,storageperiodandstoragecondition(e.g.temperature).Inaddition,safestorageguidancemaybeprovidedtoreflecttheenvironmentalsituationineachregion.Table2showsvaluesofmoisturecontentinrelationtodifferentwateractivitiesat25oCforsomecereals.

Table2.Valuesofgrainmoisturecontentinrelationtowateractivitiesat25oCforsomecereals.

Cereal

Moisturecontent(%)atvariouswateractivities

0.60

0.65

0.70

0.75

Rice

13.2

13.8

14.2

15.0

Oat

11.2

12.2

13.0

14.0

Rye

12.2

12.8

13.6

14.6

Barley

12.2

13.0

14.0

15.0

Maize

12.8

13.4

14.2

15.2

Sorghum

12.0

13.0

13.8

14.8

Wheat

13.0

13.6

14.6

15.8

Ongoingmonitoringoftheconditionofstoredgrainisessentialtoensurethegrainiskeptatacceptabletemperatureandmoisturelevelsandsubstantiallyfreeofrodents,andstoredproductpestssuchasgrainbeetles,weevilsandmites.Significantfluctuationsingraintemperatureandincreasesingrainmoisturecanprovidefavourableconditionsformouldgrowthandproductionofmycotoxins.Physicaldamagetograinkernelsduringstoragecausedbyrodentsandpests,suchasinsectsandmites,canalsocontributetoincreasesinmouldgrowth.Themycotoxinlevelininboundandoutboundgrainshouldalsobemeasuredwhenrelevant,usingadequatesamplingandtestingprogramsthatisappropriatetothemycotoxinmonitoringsystem.

Tomoreeffectivelymonitortheconditionofstoredgrain,itisadvisable,ifpossible,tomeasurethetemperatureandhumidityofthestoragefacilitiesandthestoredgrainatregulartimeintervalsduringstorage.Agraintemperatureriseof2-3°Cmayindicatemicrobialgrowthand/orinsectinfestation.Ifthetemperatureormoisturebecomesunacceptablyhigh,wherepossible,aeratethegrainbycirculationofairthroughthestorageareatomaintainproperanduniformtemperaturelevels.Aerationshouldbeconducted,ifpossible,duringperiodsoflowambientrelativehumidityofairbeingforcedthroughthemassofstoredgrain.Aerationduringperiodsofhighrelativehumiditycanactuallyincreasecondensationandawinstoredgrainwhosetemperatureisbelowambientairtemperature.Graincanalsobetransferredfromonestoragecontainertoanothertopromoteaerationanddisruptionofpotentialhotspotsduringstorage.Ifgrainspoilageormouldgrowthingrainisobserved,separatetheapparentlyinfectedportionsofthegrainandcollectsamplesformycotoxinanalyses,usingappropriatesamplingplans.Whenspoiledgrainisremoved,itisextremelyimportanttominimisethemixingofthespoiledgrainwiththeremainingportionofgrainthatappearstobeingoodcondition.Smallquantitiesofhighlycontaminatedgraincangreatlyincreasemycotoxinlevelsingrainthatisotherwiseingoodcondition.Afterspoiledgrainhasbeenremoved,itmaybenecessarytoaeratetheremaininggraintolowerthetemperatureandthemoisturetoacceptablelevels.

Forcoldclimatecountries,itisimportanttonotethatreductionofgraintemperaturebelow15oCthatcanoccurduringcoldermonthsoftemperategrain-producingregionswillcontributetosafestorageandpreventionofmouldgrowthandmycotoxinproduction.Extremelycoldtemperatureswillalsoinhibitinsectgrowthandreproduction,reducingtheriskofinsectdamage,whichcanfacilitatemouldgrowth.

Usegoodhousekeepingprocedurestominimisethelevelsofrodentpests,insectsandfungiinstoragefacilities.Thismayincludetheuseofsuitable,registeredinsecticidesandfungicidesorappropriatealternativemethodswithinanintegratedpestmanagementprogramme.Careshouldbetakentoselectanduseonlythosepestcontrolproductsthatwillnotcreateasafetyconcernbasedontheintendedenduseofthegrainsandthemaximumlevelsofpesticideresiduedictatedbyregulationorbuyerspecifications.Sincerodentpestscandamagethecropduringstorage,thestoragefacilitymustbekeptfreeofrodentssuchasratsandmicetotheextentpossible.

Theuseofasuitable,approvedpreservative(e.g.organicacidssuchaspropionicacid)maybebeneficial.Theseacidsareeffectiveinkillingvariousfungiandthuspreventtheproductionofmycotoxinsingrainsintendedonlyforanimalfeed.Thesaltsoftheacidsareusuallymoreeffectiveforlong-termstorage.Caremustbetakenbecausethesecompoundscannegativelyaffectthetasteandodourofthegrain.

Documenttheharvesting,drying,cleaningandstorageproceduresimplementedeachseasonbymakingnotesofmeasurements(e.g.temperature,moisture,andhumidity)andanydeviationorchangesfromtraditionalpractices.Thisinformationmaybeveryusefulforexplainingthec