Risky Foods, Safer Choices Avoiding Food Poisoning

Pagei

RiskyFoods,SaferChoices

ABOUTTHEAUTHORS

PETERCEREXHEisanawardwinningjournalistwhohasalsoworkedasalawyerandeditor.HespenteightyearsasajournalistforChoicemagazine(thejournaloftheAustralianConsumers'Association).HeistheauthorofthehighlysuccessfulbookBeforeandAfterRetirement(ChoiceBooks,1998)andhascontributedchapterstoseveralothertitles.

DRJOHNASHTONisaconjointSeniorLecturerinFoodTechnologyattheUniversityofNewcastleandalsodirectsaleadingAustralianfoodtestinglaboratory.Heistheauthorofseveralhighlysuccessfulbooksonhealthandtheenvironment,hismostrecenttitlebeingThePerilsofProgress(UNSWPress,1998).DrAshtonisanelectedFellowoftheRoyalAustralianChemicalInstituteandaprofessionalmemberoftheAustralianInstituteofFoodScienceandTechnology.

RiskyFoods,SaferChoicesAvoidingFoodPoisoning

PeterCerexhe+JohnAshton

ACKNOWLEDGEMENTS

Abooklikethisonecrossesmanyareasofindividualexpertiseandreliesonthecontributionsofexpertsandonavastrangeofpublishedresearchandopinionfromallcornersoftheworld,whetherinacademicorpopularjournals,websites,booksornewspaperreports.ThemosthelpfulofthesereferencesarelistedunderFurtherReading,forthosewhowishtopursuemattersingreaterdepththanispossiblehere.Werecommendthesereferencestoyou.

Theauthorswouldliketotakethisopportunitytoacknowledgethespecificassistanceandsupportofthosewhoaidedthisproject.Inparticularwewouldliketothankthefollowingpeople,gratefullyacknowledgingtheircontribution:DrMichelleAdamsandDrBobHoskenattheCentreforFoodIndustryResearchandDevelopmentattheUniversityofNewcastleDrSidCole,FellowoftheAustralianInstituteofFoodScienceandTechnologyandMattO'NeillandstaffattheAustralianConsumers'Association.RosemaryStantonkindlyreadthemanuscriptandmademanyusefulsuggestions.

AUNSWPressbook

PublishedbyUniversityofNewSouthWalesPressLtdUniversityofNewSouthWalesSydney2052Australiawww.unswpress.com.au

P.CerexheandJohnAshton2000Firstpublished2000

Thisbookiscopyright.Apartfromanyfairdealingforthepurposeofprivatestudy,research,criticismoreview,aspermittedundertheCopyrightAct,nopartmaybereproducedbyanyprocesswithoutwrittenpermission.Inquiriesshouldbeaddressedtothepublisher.

NationalLibraryofAustraliaCataloguinginPublicationentry:Cerexhe,Peter.Riskyfoods,saferchoices:avoidingfoodpoisoning.Bibliography.Includesindex.ISBN0868405221.1.Foodpoisoning.2.Foodcontamination.3.Food.4.Foodservice.5.Foodhandling.6.Foodindustryandtrade.7.Cookery.I.Ashton,John.II.Title.363.192

PrinterGriffinPress,AdelaideDesignerDiQuick

CONTENTS

IntroductionWhyGetsoWorkedupaboutItAll? 4

Part1UnderstandingFoodPoisoning,andYourProtection

7

Chapter1We'reAllinThisTogether

8

WhatIsFoodPoisoning?WhatAretheSymptoms?HowBigIstheProblem?TheFoodTheyCallBackCanYouTellIfFoodIs'Off'?HowDoYouProtectYourself?

Chapter2KnowYourEnemy!

19

BacteriaVirusesYeastsandMouldsParasitesAccidentalExtras

Chapter3WhoIsMostVulnerable?

34

ChildrenThosewithReducedImmunityWhyAreOlderPeopleatGreaterRisk?PregnantWomen

Chapter4HowDoIProtectMyself,MyFamilyandFriends?

38

HowYourBodyProtectsItselfFoodStorage,PreparationandPreservationRecognisingFoodAdditives

PartIIAWalkthroughtheShoppingCentre

45

Chapter5TheDelicatessen

46

SmallgoodsRulesforSmallgoodsHerbsandSpicesDairyFoodsJamsandPreservesPate

Chapter6TheGreenGrocer'sShop

59

PotatoesMushroomsandFungiAlfalfaSproutsPackagedRawSalads

ManteshwerTypewritten Text

ManteshwerTypewritten TextAhashare.com



Chapter7TheButcher'sShop

64

SpoiledMeatMincedMeatsandSausagesWholePoultryMarinatedMeatsProtectionStrategies

Chapter8TheFishShop

69

FishyRisksATaleofToxinsMolluscsProcessedFish

Chapter9ASweetTooth

75

CakesIcecreamandOtherFrozenTreatsChocolate

Chapter10TheSupermarket

81

CannedFoodsFrozenFoodsTheGoodEggVegetarianMeatSubstitutes'Useby'DatesIsThatMould?

Chapter11Drinks

88

TheTownWaterSupplyIsBottledWatertheAnswer?FruitJuicesMilkDrinksDirtyIce

Chapter12TakeawayFoodShops

95

HamburgersSaladBarsDonerKebabsRicePizzaChickenSandwiches:TheSafeAlternative?WhenSaferChoicesAreImportanttoYouFoodWorkersSickatWorkPicnicTips

PartIIITravel,PartiesandWhoLooksafterUs

105

Chapter13EscapingtheTravelBugs

106

WhichCountriesPosetheGreatestRisk?CruiseBluesChoosingaRestaurantSafeWaterBottledWater:IsItSafe?ProbioticaidSalads:ADifficultChoice

Chapter14It'sMyParty...

114

CookinginAdvanceDealingwithLeftovers

Chapter15SchoolLunches

117

CanteenorHomePackedLunches?TipsforPackagedLunchesChildrenandGastroenteritis

Chapter16FoodAllergies

120

WhatAretheMainFoodAllergens?HowCanIFindoutIfIHaveaFoodAllergy?

Chapter17StoringFood

124

TheFreezer:WhatCanItDoforMe?TheRefrigeratorFridgeandFreezerTipsHowLongWillFoodLast?InthePantry

Chapter18YouandYourKitchen

134

HowShouldICleanMyKitchenBenches?CuttingBoards:WoodorPlastic?PersonalHygiene

Chapter19TheBusinessofFood

139

QualityControlDetectingtheForeignLegionTestingandComplaintsNewTechnologiestotheRescueNewHopes,NewProblems

Chapter20FutureUncertain

148

AretheRisksIncreasingorDecreasing?GettingaroundandBecomingKnownAreWeOverlyDependentonAntibiotics?ChangingOurPreferencesTheGeneArmouryARoleforGovernment

Chapter21OnefortheRoad

157

Glossary 158

FurtherReading 159

Index 160

INTRODUCTION:WHYGETSOWORKEDUPABOUTITALL?

Foodpoisoninghappensweallknowthat.Butitusuallypassesquicklyandwegetwellagain.Itwasjustbadluckoristheremoretoit?

Theworldweliveinisverydifferentfromtheworldof30yearsago.Notonlyaretheremorepeople,moretravelandterribleflu,andothervirusesmovingaroundtheworldwithastonishingspeed,butalsonewfoodpoisoningbacteriasuchastheingloriouslynamedE.coliO157:H7,firstreportedbackin1982.Thisbacterium,whichisnowcarriedintheintestinesandfaecesofupto40percentofcattleinsomecountries,cancausenotonlyvomitinganddiarrhoeabutcanleaveanaffectedchildpermanentlywithdiabetes.Ithasalsobeenknowntoproducebraindamage.

Fortunatelynotallfoodpoisoningbacteriaproducesuchseriousandpermanentsymptoms.And,inacountrylikeAustralia,wearemercifullyfreefrommuchseriousfoodborneillness.Yetthehumanraceisinadvertentlyplayingaroleinitsownfoodhazarddevelopment.Technologyhasproducedtheconveniencesofmobilephones,microwaveovens,cheaptravel,megafarmsandfastfoods,butsomehowintheequationwehavealsocreatedanenvironmentconducivetotheemergenceandspreadoffoodpoisoningmicroorganismswiththepotentialtoaffectusall.

Thiswillchangethewaywelive.

Manyofthefoodpoisoningbacteriawhichnowconcernauthorities,suchasCampylobacterjejuni,haveonlyemergedinthepast25years.Yetmorethan11,000casesofCampylobacterjejunifoodpoisoningwerereportedinasmallcountrylikeAustraliain1998,withanuntoldnumberofcasesgoingunreported.

Thischangingfoodenvironmenthasnecessitatedthewritingofthisbook.Itcontainstheinformationyouneedtohelpyoutochoose,storeandpreparefoodinwayswhichwillreducetheriskofcontractingafoodborneillness.Wediscussthingslikemealplanning,cookingtemperatures,safefoodstorageandmanyotherfactorswhich,webelieve,nowrequiremorediligencethanweperhapshavegiventheminthepast.

Therearerealincentivesfordevelopinggoodhabits:

Yourfoodwilltastebetterandbebetterforyou.Thesamegoodpracticeswhichkeepfoodsafealsopresentyouwithmealsthatarefreshandwiththeirfullcomplementofnutrients.Badpracticesdegradeyourfoodasthebacteriamultiply.Goodpracticesdeliverfoodwiththerightaromas,texturesandtastes.

You'llsavemoney.Doctors'bills,medicinesandtimeoffwork(orasouredholiday)aretheexpensiveconsequencesofaboutoffoodillness.

Yourfriendswillcontinuetocomeovertoyourhouse.Ifguestsfeeltheygotfoodpoisoningatyourplace,oriftheysawthewaythefoodwaspresentedandwerenotimpressed,youmightbeleftwonderingwhytheynolongeracceptyourdinnerinvitations.

Youlearnhowtolookaftervulnerablepeople,helpingthemtogoodhealth.Manyofthefoodbornepathogensareofparticularconcerntothosewhoaremostvulnerableinoursocietythefrailelderly,babiesandveryyoungchildren,thoseundergoingcancertreatmentorotherwisewithloweredimmunity.Goodfoodpracticeshelpsupportthehealthofyourfamilyandfriends.

Tohelpyouwiththistask,wehaveprovidedagreatdealofinformation:aboutmicroorganismswhichcanmakeussick,howtheygettous,howtheyworkwithinus,ourdefences,howthefoodindustryworks,andwhatthefutureholds.Alongthewaywehavesimplifiedthecomplexitiesofmuchofthisinformationsothatyoumightmorereadily

graspprinciplesandruleswhichyoucanthenapplyinyourdailylife,whethershopping,attendingfunctionsorsimplyeatingathome.

Thisbookisdividedintothreeparts.PartIhighlightstheprevalence,dangersandimpactoffoodpoisoning,liststhemostcommonfoodpoisoningagentsandhowtheyaffectyou,andlaysdownsomegeneralrulestoprotectyourselfandyourfamily.PartIItakesyouonawalkthroughtheshoppingcentre,withchaptersdealingwithseparateshopssuchasthedelicatessenorfishshop,andpointsoutwhichfoodsareriskier,andwhicharesaferchoices.PartIIIlooksatfoodpoisoningrisksfromtraveldestinations,partiesandpackedlunches,whatyoucandotostoreandpreparefoodmoresafely,whatthefoodindustrydoes,andotherriskstodowithfoodsuchasallergiesandgeneticallyengineeredproducts.

Manyofthelists,tablesandtipsinthisbookarebasedontheassumptionthatcertainfoodshavebeentreatedandhandledequally.Byreturningtobasicprinciplesoffoodscienceitispossibletosuggestthatonefoodisriskierthananother.Thepointmightbecontroversialandcouldbearguedaboutbyexpertsforever.Thisbook,however,iswrittenforconsumerswhowantsomehelpandguidanceindealingwithdifficult,sometimesobscureproblems.Inprovidingthisguidancethewritersare,insomeinstances,statingapersonalopinion.

WehaveincludedmanycasestudiesfromtheUnitedStatesandBritain,aswellasfromAustralia.InsomecasesthebacteriaorviruseswhichfeatureinthoseoverseasstoriesaremoreofaproblemtherethaninAustralia.Yettheyremainrelevanttoallwhotravelwidely.Forexample,ifyou'reoneofthethousandsofAustralianswhohaveembarkedonaUnitedStatesfamilyholiday,itisworthknowingthatyoushouldcheckyourhamburgermincehasbeencookedthoroughlyhamburgershavebeenanongoingsourceoffoodborneillnessintheUnitedStates.SimilarlytheUnitedStateshassufferedsomemajoroutbreaksofillnesstracedtolocalwatersupplies.AgainitisaproblemthatAustraliansarenotnecessarilypreparedfor.

Whenwebeganourresearch,weconsideredwhethertheconcernintheUnitedStatesoversafedrinkingwaterandfruitjuiceswasrelevanttoAustralians.Bythetimewecompletedthisbook,AustralianshadwitnessedthefrenzyarisingfromtheSydneywaterscareandtherecallofNippy'sAussieGoldandOrangeGrovefreshchilledfruitjuicesforSalmonellacontamination.Ahealthconcernmayariseononesideoftheworld,butitshouldnolongercomeasasurprisetoseeitpopupinourownbackyard.

Areyoupreparedtotakeariskoffoodpoisoning?Sometimestheanswerwillbe'Yes',atothertimes'No'.Yourownstateofhealthwillhaveagreatbearingonhowyouanswerthisquestion.Wehavefoundthatmanypeoplewhoworkinthefoodindustryhavesafetytipswhichtheyapplyintheirownlives.Somewillnoteatcustardtarts,forexample,simplypreferringtoremoveawholecategoryoffoodfromtheirordinarydietratherthantakewhatatmosttimeswouldbeaverysmallrisk.Inthisbookwe'llshowyoumanyofthesetips.

Itisimportantfromtheoutsetyouunderstandthatsuchtipsareasimplificationofverycomplexissuesandprocesses.Asocalled'risky'food,provideditispreparedandhandledproperly,mightbequitesafetoeat.Atthesametime,a'safer'foodmightstrikeyoudownwithillnessbecauseitwashandledbyachefwhofailedtowashhishands.

Thereareplentyofcorporationsandadvertiserswhowanttoscareusallaboutthesafetyofourfoodsupplyandthewaywerunourhomekitchens.Werejectthefearcampaign,andtheirnotionthatcommercialantibacterialdisinfectantsarenecessaryinthehome:goodfoodpracticesandsoapandwaterarecompletelyadequate,andhavebeenforcenturies.Withoutbuildinguptherisksor,ontheotherside,playingthemdown,webelievethatconsumersarmedwithgoodinformationwillgetthebestoutoftheirmealsgreaterenjoyment,greatersafetyandbetterhealth.

Wehopethisbookwillhelpyoudevelopapositiveattitudetofoodandmealpreparation.

PARTIUNDERSTANDINGFOODPOISONING&YOURPROTECTION

Chapter1We'reAllinThisTogether

Haveyoueversufferedfromfoodpoisoning?Maybeyou'vewokenuparoundthreeo'clockinthemorning,clutchingyourstomachinpain,andcursingtherestaurantwhereyouhaddinner.Sometimesyoudevelopabadfeelingaboutaparticularfoodalmostassoonasyou'veputitinyourmouth.

Minutes,hours,days...foodpoisoningcanbefastorslow.Sometimesyouanticipateit('Idon'tfeelgoodaboutthoseoysters!')anditnevershowsup.Forthisreasonitcanbedifficulttoknowwheretolaytheblame.Wasitlastnight'srestaurantoryesterday'slunchofreheatedleftovers?Canyourightlycalltherestaurantandcomplaintothemanager,orshouldyoubelookinginsteadforaproblemwithinyourownkitchen?

Foodpoisoningisanissueofgreatconcerntoallofus.Maybeyouareaparent,wantingtodowhatisnecessarytoprotectyourchildren.Perhapsyouareabusinesstravellerwhocannotaffordtocomedownsickwhileracingtomeetdeadlinesandenduremeetings.Forsomeofusitisamatterofcaringforfriendsorfamilywhoareinpoorhealthandatriskofseriousillnessfromanyinfectionpeoplewithcompromisedimmunesystems,theelderly,pregnantwomenandbabies.

Themoreyouknowaboutfoodpoisoning,thebetteryourchancesofenjoyingyourtravelsandkeepingyourfamilyindailygoodhealth.

WhatIsFoodPoisoning?

TheWorldHealthOrganisationdefines'foodpoisoning'asanyillnesscausedbyorthoughttoberelatedtotheconsumptionoffoodorwater.Itisaverybroadconcept.Inthisbookwewillusetheterm'foodborneillness'.

Expertssometimesdividefoodborneillnessintodifferentcategorieswhichassistintheiranalysisofwhatisgoingon.Forexample,somemicroorganismsmultiplyinfoodandproduceatoxinwhichpoisonsuswhenweeatitothermicroorganismsmultiplyinsideourbodies,havinggainedaccesswhenfoodordrinkareconsumed(orfingerslicked).

Noteveryonewhoeatsortakesinaharmfulmicroorganismortoxinwillfallsick.Sometimesthisisbecausethe'dose'thenumberoforganismsorquantityandstrengthofthetoxinisinsufficienttocauseillnesssometimesthepersonhasadegreeofimmunityduetopriorexposuretothemicroorganismsorbecausetheyenjoybetterhealthgenerally.

Apersonwhocarriestheharmfulorganism,yetshowsnosymptoms,mightstillbeablepassitontosomeoneelse,whodoesbecomeill.Wecanbesymptomless('asymptomatic')carriersoffoodbornepathogens.

Whatisitthatmakesussick?

Foodpoisoningisusuallythefaultofbacteriaandother'bad'microorganisms.Wegetsickbecausewehaveconsumedthembyeatingordrinking,orbyputtingobjectsinourmouthsthatarecontaminatedwiththem.

Thefourmostcommonsituationsthatcanresultinanepisodeoffoodborneillnessare:

poorstorageofthefood

inadequatecookingorreheating

crosscontamination:fromonepersonorutensil/surfacetoanother

infectedfoodhandlers.

Onceinsideourbodiestheytravelthroughthestomachandintotheintestines.Mostfoodpoisoningbacteriatargetthecellsofthesmallintestine.Someattachtotheintestinewallsandstarttomultiply,effectivelycolonisingtheareabeforeproducingtheirtoxinsothersreleasethetoxinwithouthavingtocreateacolonyfirst,sometimessimplyfromwithinthefoodmassitselfotherswillpassthroughtheintestinewallsandheadforotherpartsofthebody,forexample,theviruswhichcauseshepatitisAgoestotheliver.Thenwegetsick.

However,thisisonlypartofthestory.Therearemanythingsthatmakeussick,andbacteriaareonlyonetypeofculprit.Therearegoodbacteriaandbadbacteriatherearegoodchemicalsandbadchemicals.Almosteverythingyoucaneatisapoisonifyouswallowtoomuchofitevenvitaminsandotherhealthythingsinourfoodanddrink.Itisusefultoknowthedifferentsourcesofproblemssoyoucanthenunderstandwhichwaytotreatthem,andhowtoprotectyourself.

Whoarethebadguys?

Asyoumightexpect,therearemanythingsbacteriaandviruses,moulds,yeasts,parasitesandchemicalswhichcanleadtothesymptomswecallfoodpoisoning.YouhaveprobablyheardofSalmonella.Therearemorethan2300differentkindsofSalmonellabacteria,butyoudon'tneedtoknowaboutthemall,andnotallofthemwillmakeyousick!Inotherwords,wecanmakeamoremanageablelistoftheproblembacteria,virusesandothermicroorganisms.ThatformsthesubjectofChapter2.

Notalltoxinsthatgiveusfoodpoisoningcomefrommicroorganisms.Therearealsosomeothernaturalpoisonstobeawareof:

Whenpotatoesturngreenincolouritisasignthatthepoison'solanin'hasbeenproduced.

Oxalicacid,foundintheleavesofspinachandrhubarbcan,intheory,leadtokidneydamageasaresultoftheformationofinsolublecalciumoxalatecrystals.

Theseaishometosomeverypowerful,allnaturaltoxins.Thetoxininpufferfishhasbeenknowntokillthepersonwhoeatsit.InJapanthisfearispartofwhatattractsthethrillseekingdiner.Butit'snotjustaconcernfortheJapanese.Pufferfishhasturnedup,accidentally,inafrozenfoodproductsoldinAustralia.Whenthecompanybecameawareofthemixup,theproductwasrecalled.Anotherseafoodpoisonis'ciguatoxin',whichhasalsoledtoafoodrecallin

Australia.Thistoxinstartsinmarineplantswhicharetheneatenbysmallfishwhich,inturnareeatenbylargerfish.Asitmovesupthefoodchainweseetheconcentrationofthepoisoninlargefishcaughtnearcoralreefs.Theonestobecautiousaboutarelargepredators,suchassnapper,coraltrout,coralcod,Spanishmackerelandredemperor.

Sometoadstoolsandmushroomscanbeverytoxic.AccordingtoarecentradioreportfromRussiaatleastonepersoninthatcountrydieseachdayfromeatingthewrongtypeofmushroom.

ThemostcommoncausesoffoodPoisoning

ThemostcommoncausesoffoodpoisoninginAustralia(indescendingorder)are:CampylobacterSalmonellaHepatitisAShigellaandYersina.IntheUnitedStatestheordergoes:CampylobacterjejuniSalmonellaShigellaCryptosporidiumfollowedbyE.coli0157:H7.AndinBritainthetopfiveare:SalmonellasmallroundstructuredvirusClostridiumperfringensBacilluscereusandfifth,Campylobacter.

Whileallthreenationsfacefoodborneillnessfromallofthese,thereisashiftinemphasisbetweenthoseatthetopofeachlist.(Someofthedifferencesdependontheintensityoffollowupofcasesbypublichealthauthorities,andontheabilityoflaboratoriestodetectfoodillnessagentsatwork.)

WhatAretheSymptoms?

Symptomsoffoodpoisoningmayincludethefollowing:

diarrhoeawatery,maybeevenbloody

nausea

vomiting

dehydration(duetofluidlossfromdiarrhoeaandvomiting)

fever

paininthestomachorabdomen

swellingintheabdomen

dizziness.

Inextremecases,severeillnessordeathcanresultfromcertainfoodbornepathogens.

Don'tbealarmed!Notallfoodpoisoningisfatal.InAustralia,recentkillershavebeen:SalmonellaVibrioparahaemolyticus(cholera)E.coliStaphylococcusaureus.Thisrepresentsonlysixdeathsovera15yearperiod(19801995).Howeverasthisbookwasgoingtopress,sixfatalcasesoflisteriaassociatedwitheatingfruitsaladwerereported.FoodpoisoningisnotabigkillerinAustralia.Ifyoufindyourselfinapoornation,however,theriskbecomesmorereal.IncountrieslikeAustralia,NewZealandandBritainwegrowupwithlittleappreciationoftheriskelsewhereontheplanet.

Havingsaidthat,therisk(althoughsmall)ofalifethreateningattackoffoodpoisoning,remainsrealeveninadevelopednation.Attheendof1998,12peoplediedintheUnitedStatesfromwhatisbelievedtohavebeenpackagedmeattaintedwithListeria.Itwasasingleinstanceofmeatcontamination.Twoyearsearlier,20elderlypeoplediedfromanE.coli0157:H7infectionincentralScotland.Thesenumbersfordevelopedcountriesarerelativelysmallwhenthesizeofthepopulationisconsidered.Itisatragedywhenithappens,butitisnotoften,andfewdie.

ChronicDiarrhoea

Forsomepeopleaboutofdiarrhoeacanlastforweeks.Isfoodordrinktoblame,ordoestheproblemlieelsewhere?Diarrhoeacanbecausedbyfoodpoisoning.AtfaultmaybeparasitessuchasGiardiaandCryptosporidium,viruseslikeNorwalkorRotavirus,orbacteriasuchasCampylobacter,E.coli,

Listeria,SalmonellaorShigella.Buttherearemanyotherreasonsforchronicdiarrhoeawhichshouldnotbeignored,andforwhichmedicaltreatmentshouldbesought,including:

theuseofantibiotics

cancer,andcancertreatmentdrugs

diabetes

colitis

foodallergies

somefoodadditivesorcomponents(e.g.fructose,sorbitolandothers)

medicationsfortreatinghighbloodpressure

Crohn'sdisease

thyroidandendocrinediseases

previoussurgeryorradiationoftheabdomenorgastrointestinaltract.

HowBigIstheProblem?

Foodpoisoningfiguresareveryuncertain.InMay1999,theAustraliaNewZealandFoodAuthority(ANZFA)releasedareportestimatingthat11,500Australianssufferedfromfoodpoisoningeachday,costingthenationmorethan$2.6billionayear.Accordingtotheresearch,absenteeismfromworkduetofoodpoisoningcostAustraliamorethan$370millionin199697alone.Whilehighlightingjusthowsafethefoodsupplywas,ANZFAsaidAustraliansfacea1in5000chanceofgettingfoodpoisoningfromameal,outofanestimated20billionmealseateninoneyear.Someauthoritiesbelievefoodpoisoningisontheincrease.

In1995theUSDepartmentofAgriculture'sFoodSafetyBranchattemptedtoestimatelossestotheUScommunityfromfoodborneillness.Includingmedicalcostsandlostproductivity,itcameupwitharangeofUS$5.69.4billionannually.Fouryearslater,inearly1999,theUSDepartmentofAgriculture'sUndersecretaryforFoodSafetyplacedtherangemuchhigher,atbetweenUS$6.637billionannually.

TheUSCentersforDiseaseControlandPrevention(CDC)reportedthefindingsoftheFoodNetsurveillanceprojectinApril1998:'Theoverallburdenofdiarrhealdiseaseisgreat.FoodNetestimatesthat360millioncasesofdiarrhealillnessoccurperyear,resultinginapproximately28millionmedicalconsultations.'TheCDCestimated,fromitsresearch,thatapproximately8millioncasesoffoodbornebacterialinfectionsoccurredin1997intheUnitedStates.

AstudyofreportedcasesoffoodrelatedillnessinEnglandandWalesfrom1992to1994identified1594distinctoutbreaks,affectingatleastthe34,158peoplewhoreportedtoadoctororhospital.Ofthese,2percentwereadmittedtohospital,and55peopledied.Overthethreeyearsoftheperiodunderreview,halfthecaseswerefoodborne,andafurther40percentwerepassedbypersontopersoncontact.

Thereportedcausesalsovary.AccordingtotheUnitedStates'CDC,therearemorethan250differentdiseaseswhichcanbecausedbycontaminatedfoodordrink.Somearenolongerthebigproblemstheyoncewere(suchasbotulism)whilenotifiedcasesofcertainothersmaybeontheincreaseoverthelastdecadeorso(forexample,reportedinfectionsduetoListeria).Itisnotastaticpicturebutamoveablefeastofsorts:sometimesthefiguresgoup,sometimesdown.

Morethan39,000casesofsalmonellosis(illnessduetoSalmonella)weredocumentedbytheCDCin1996alone.However,thisisjustthetipoftheiceberg.Expertsestimatethat,intheUnitedStates,thetruenumberofcasesfallsintherange696,000to3.8millioneachyear.This,ofcourse,isavastrangeofpossiblecases,servingtoindicatejusthowinexactisourknowledgeofthefullimpactoffoodpoisoningandfoodintoxicationinourcommunities.Evenallowingforthosestatistical

shortcomings,thenumbersarehuge.

Inpracticefewpeoplewhocomedownwithfoodborneillnessseekmedicalattentionorotherwisearerecordedasanofficialstatistic.Thatiswhythehealthauthoritiestalkaboutwideestimatesratherthanhardnumbers.Peoplesufferathome,missingtheodddayofschoolorwork,perhapsblamingtheflu(manyofthesymptomsaresimilar)orshruggingtheirshouldersandgettingonwithlife.

FoodpoisoningisrarelyfatalinAustralia.InasubstantialreviewofthesituationinAustraliafortheyears1980to1995,performedbyScottCrerarandothersandpublishedintheMedicalJournalofAustralia,128outbreaksoffoodbornediseasewereidentified.Almost6000peoplewereaffectedbytheseoutbreaks,butonly185werehospitalised,andonlysixpeopledied.

ItisonethingtoknowthatnotmanyAustraliansdieorendupinhospitalthankstofoodborneillnesses.Thedramaticcasesarecomparativelyfew,giventhesizeofthepopulationandthenumberofmeals,foodsandbeveragesweconsume.Butwhataboutthelessdramaticinstances?Howoftendoesoneofyourfamilymemberscomedownwiththesymptomsoffoodpoisoningorsomefoodrelatedillnesssuchasmilddiarrhoea,nauseaorpaininthebelly?Ifweknewtheanswertothisquestionwewouldhaveamuchbetterunderstandingabouttherealimpactandcosttothecommunityoffoodborneillness.

ResearchiscurrentlyunderwayinboththeUnitedStatesandBritaintofindthetrueincidenceoffoodborneillnessfortheirpopulations.InfactAustralianscientistshelpeddesignthesurveyscurrentlybeingusedintheUSresearch.InitiallyitseemedthatAustraliawouldnotbecarryingoutitsownresearch.However,latein1998thefirstSentinelSurveillanceProjectgotunderwayinAustraliatofindouthowmanyofussufferfromfoodpoisoningandotherfoodborneillness,andhowoftenitstrikes.TakingplaceintheHunterregionofNewSouthWales,theprojectbytheHunterPublicHealthUnitoftheNewSouthWalesGovernment,involvessurveyinganareawithapopulationof500,000people.Inparticulartheresearcherswillbelookingforevidenceofactionoftwoofthemostcommonharmfulfoodbacteria:SalmonellaandCampylobacter.Thefirstresultsareexpectedbytheendof1999.

AnearlierpilotstudytookplaceinCanberra.Forthatstudy,telephonesurveyswereundertakeninhouseholdsthroughoutthecity,questioningthepersonwhowasthefoodhandlerattheirhome.Resultsindicatedthatupto60percentofdiarrhoealillnesscouldbetheresultofpoorfoodhandlingpracticesathome.

ResearchfromtheUnitedStatesconfirmsoneimportantfindingofthisCanberrastudy:ordinaryhouseholdersdon'tappeartoblametheirownfoodhandlingpractices,orrecognisethehazardtheytrulycanbe.

FoodborneillnessalsoappearstobeontheincreaseintheUnitedStateswheretherearearound400to500outbreaksreportedannually.Inpartthisispossiblyduetobetterrecordingandmorethoroughresearch,butwecan'tdiscountthepossibilitythatmorepeoplearesimplygettingsickermoreoften.Importantcontributingfactorsmaybethewayswerunourkitchens,changesinthefoodsweeat,andtrendsinhowandwhereweeatourmeals.Wewillconsiderthesefactorslater.

Wheredoesillnessstrikemost?

Itiscommonforthefoodindustrytolaytheblameforfoodpoisoningonpoorhygienepracticesinthehome.YetinAustralia,ANZFAconsidersthat80percentoffoodborneillnessoccursoutsidethehome.Stillmuchfoodrelatedillnessispreventable.TheBritishresearchersnoted:

Mostoftheoutbreaksreportedandtheassociatedmorbidityandmortalitycouldhavebeenpreventedbyfollowingstandardfoodhygienepractices,implementinginfectioncontrolpolicies,andensuringthatfoodenteringkitchenswasofthehighestmicrobiologicalqualitypossible.

AreviewofinstancesoffoodrelatedillnessinEnglandandWalesfrom1992to1994investigated1594generaloutbreaks.Thetable

NUMBEROFOUTBREAKSOFFOODBORNEILLNESSFROMVARIOUSLOCATIONS

Place Mainlyfoodborne

Mainlypersontoperson

Nursinghomesandsimilarinstitutions

59 199

Hospital 19 156

Restaurant 170 2

Hotel 75 25

Home 101 6

Schools/colleges 30 64

SourceSurveyofEnglandandWales,199294,USCentersforDiseaseControlandPrevention,CDRReview,29March1996.

aboveshowsthemostcommon'settings'orplaceswheretheillnesswaspickedup.

Arehomessaferthaneatingout?There'salotofdifference.Takenasawhole,eatingoutatrestaurants,cafes,canteens,pubsandhotelsaccountedfor27percentofoutbreaksnursinghomesandthelikeadded22percentandhospitals15percent.Theprivatehomeonlyaccountedfor9percentofoutbreaks.

Alsointerestingisjusthowoftenafunctionorpartywastheoccasionwhenthebaddeedtookplace.Thevastmajority(88percent)ofoutbreaksconnectedwithprivatehomesoccurredatweddingreceptions,dinnerparties,engagementandbirthdayparties,barbecuesandothergroupmeals.Justoverhalftheoutbreakstrackeddowntocommercialpremises(suchasrestaurants)werealsofunctions,notnormalpublictrading.

Clearlythefunction,whetherataperson'shomeorinacommercialsetting,isanoccasioncallingforgreatercarebycaterersandconsumersalike.Expertshavesaidthatthepracticesandfacilitiesfoundinthehomearenotappropriateforcateringforlargenumbersofpeople.Inmanyoutbreaksthefoodwaspreparedatsomeone'shomeandthentransportedtotheplaceoftheparty(acommunityhall,forinstance).Asyoureadthroughthisbook(particularlyChapter19)youwillseethelengthstowhichcommercialpremisesmustgoinordertoprovideanacceptableleveloffoodsafety.Itisbeyondwhatmostofuswouldbepreparedtodoinourownhomes.

TheFoodTheyCallBack

Haveyoueverboughtafoodproductwhichwaslaterthesubjectofafoodrecallcampaign?Usuallytherecallisbroughttotheattentionofthepublicbyaspecialnoticeinthenewspaper,orasignmightbedisplayedattheentrancetothesupermarket.Intheworstcases,wherenumbersofpeoplehavebecomesickaftereatingordrinkingtheproduct,you'llhearabouttheproblemontheradioortelevision.

Foodrecallsonlydealwithasmallnumberofthefoodsandoccasionswhereconsumerhealthisplacedinperil.Nevertheless,theyarewelldocumented,andthathelpsuslearnusefulinformationaboutwhereandhowfoodbornedangersarise.Forastart,foodrecallsarenottobedismissedassomethingthatonlyhappensto'bad'foodmanufacturers.Someofthefoodswhichhavebeensubjecttoaproductrecallcampaignsincethemid1990sincludewellknownbrandnames.

ThelistandquotesonthenextpagearefromthelistofpublicrecallnotificationscompiledbytheCommonwealthDepartmentofIndustryScienceandTourism(ConsumerAffairsDivision).Asfarasweareaware,allthoserecallslistedabovewereinstancesofthemanufacturerordistributortakingpreventiveactiontolookaftertheircustomerswherecontaminationoraforeignobjectwasintroduced(orwassuspectedofbeingintroduced)tothefoodaccidentally.

Thesecondpointtonoteisthatnofoodgrouporpackagingstyleseemsimmune:fromdairytomeatandfishvegetablestosnackfoodscans,glassjarsandpacketfoods.

Thesedaysitseemstherearealotoffood

FOODRECALLSINAUSTRALIA

Attikifettacheese 'Listeriamonocytogenescontamination'

BiLochoccoatedicecreams 'MaybecontaminatedwithListeria'

CadburySchweppesblackforestfruitandnutchocolateblocks

'Consumerswithanallergytonutsmayhaveanallergicreaction'

ClassicandJosephineLAGourmetvariousdips

'MaybecontaminatedwithListeriamonocytogenes'

Farmland(Coles),BiLoandAlpinemudcakes

'Theremaybeanomissionofeggsbeinglistedoningredientlabelling'

DonLatvianliverspreadanddelisupremekabana

'ContaminatedwithSalmonellabacteria'

GoldenCirclecannedpeas 'Doesnotcontainpackingliquid(syrup)thereforecanshavenotreceivedthescheduledthermalprocess'

Heinzappleyoghurtdessertbabyfood 'Maycontainglassfragmentsinthejars'

Bird(PontiacTradingCompany)peanutsnack

'Highleveloffungalcontamination'

SalmonKingsmokedsalmon 'MaybecontaminatedwithListeria'

Santoscrushednutsandcrushedmixednuts

'PossibleSalmonellacontamination'

Plumrose(Simplot)cannedchicken,turkey,delihamandlegham

'Damagetocansmayallowairpenetrationresultinginproductdeteriorationandpotentialhealthrisk'

Smith's'Twisties'(cheeseandchicken) 'Maycontainfragmentsoffinewire'

Streets'GraveRobber'icecream 'Confectionarypiecescontainedintheicecreamarehighinleadandcadmium'

Giardiniera(Triou)pickledvegetables 'Possiblechemicalcontaminationduringmanufacture(formaldehyde)'

recallcampaigns.Aretheremorethanever,orarewejustmoreawareofthem?ThenumbersofrecallsinAustraliaforfoodandbeveragesfortheyears198697areshownonpage15.Inthelate1980sthenumbershoveredaroundfivetoseveneachyear.Thisrepresentedroughly2or3percentofallproductrecallsincludingcarsandotherhouseholdproductsfortheyear.

Intheearly1990sthenumbersandproportionsjumpedtoanewlevel.Proportionally,foodrecallswereincreasingaspartofthetotalmixofconsumerproductrecalls.Anotherleap,inthemid1990s,sawfood/beveragerecallshitnewheights:52recallsintheoneyear,representing15percentofallconsumerproductrecallcampaigns.Thereforewecansay:yes,thenumbersoffoodandbeveragerecallshavebeenincreasingandyes,foodandbeveragerecallsrepresentanincreasingproportionofallconsumerproductrecalls.

Thisdoesn'tnecessarilymeanthattherearemoreproblemsthaneverwiththesafetyofourfoodsupply.Itmightsimplybeacasethatmorecompaniesarecomingforward,or

beingcaught,whentheyhaveaproblemwiththeirfoodandbeverageproducts.Oritmightbeacasewhereabitofbothisgoingon.

IntheUnitedStatesin1998,bycomparison,therewere39foodrelatedproductrecalls.Surprisinglyalmostallconcernedmeat.Ofthese,thelargestsingleproblemproductwasmincedmeat(forhamburgerpattiesandotherwise),with13occasions.Hamandsausagesfacedfourrecallseachchickenproductssix(threeofwhichwereduetometalobjectsturningupinthefood)andFrankfurtsthree.Aroundhalfofallrecallswereforbacterialcontamination,whileanotherseveninvolvedbitsofmetal.

InAustralia,too,asurprisingnumberofrecallsaretodowithforeignobjectsappearinginthefoodsordrinks.InJuly1995,foodrecallcampaignswerelaunchedovermetalshavings(somepacksofKellogg's'RiceBubbles'and'CocoPops'),glassfragments(glassjarsofAyamseafoodandchickencurrypaste),andstainlesssteelwirefromamanufacturingsieveincansofinfantformula('Infasoy').

Many'foreignobject'recallsareduetofoodcontaminationbybrokenpartsofthemanufacturingassemblyline:anutfallsoffaboltinthemachine,awiresievewearsoutandfragments,apieceofelectricalwirefallsout.Othersaremoreunusual:acapsuleofantibioticAmpicillinTrihydratefounditswayintosomeseedlessdateswirebristlesfromabrushendedupinsomewholemealfruitbarsandcausticcleaningsolutioncontaminatedmilk.

Anothertypeofforeignobjectcontaminationwhichalsomightleadtoarecallcampaigniswherethewrongfoodgetsintothepackage.Whiletheremightbenothingwrongorunhealthyaboutthe'foreignfood'itself,thelabellingoftheproductisnowincorrectand,forsomemembersofthecommunity,theremightbeahealthissue.Allergiesareaclassicexample:peanutsinchocolatebars,hoummosandricecrackersgluteninapackofsausageslabelled'glutenfree'.Youcanunderstandthepotentialhealthrisksthesetypesofmessupscanbringabout.

Foreignobjectsrepresentalargeproportionofallfoodandbeveragerecalls:around45percent.However,unlikefoodrecallsduetobacterialcontamination,itisgenerallythecasethatonlyafewpacksmaybeonlyonehavebeenfoundtobeaffected.Bycomparison,microorganismsrepresentthelargestthreattopopulationsofpeople.

CanYouTellIfFoodIs'Off'?

Foodrecallsareonlythetipoftheiceberg.Ifthefoodworldisfullofdangersthevastmajorityofwhich,wehastentoreassureyou,willpassyoubyitisfairtoask:CanIpickbadfoodfromgoodfood?CanItelliffoodis'off'or'spoiled'?

NumberofFoodRecallsinAustraliaSourceCommonwealthDepartmentofIndustry

ScienceandTourism(ConsumerAffairsDivision)

Insomecasesyoucancertainlyrelyonyourwhatyoursensestellyou.Therearevisualsignsthatthefoodhasgone,orisgoing,'off',spoiledorstale.

Haveyoueverseen:

breadwithmouldonit

greenpatchesonpotatoes

blackspotsonfruit

fishwithdulleyes?

Therearealsosomeoccasionswhenyoucansmellthatafoodisspoiling.Haveyoueversmelled:

a'wetdog'odourfromwine

rottenegggas

sourmilk

oldmeat?

Sometimesit'syoursenseoftouchwhichgivestheclue.Haveyoueverfelt:

vegetables,suchaszucchini,whichhavegonesoftandsquishy

slimyham?

Ifyoulistenedtowhatyourmotherorgrandmothertoldyou,youwouldknowmanyofthesignsthatfoodiseitherspoilingor,alternatively,isinpeakcondition.Thisisimportantfolkknowledgethathashelpedussurvivefromonegenerationtothenext.

Butnotallfoodpoisoningissoeasilydetected.Inmanycasesthetruenatureofthefoodordrinkcanonlybeknownaftertestinginalaboratory.Foodpoisoningmightnotaffectthelook,smell,feeloreventasteofthefoodordrink.

Useyoursenses,butdon'trelyontheminallcircumstances.

Whynot?Thereisabasicconfusionhere:themicroorganismswhichbreakfood

WAITER,THERE'SATACKINMYHAMBURGER!

Whileeatingahamburgeratthebeachoneday,oneoftheauthorstookabiteandwassurprisedtofindathumbtackstickingintohismouth.

Howdidthetackgetthere?Maybetheshopusedtackstopinupthemealordersabovethefoodpreparationareaperhapsithadbegunitsvoyageinthemincedmeatfromthebutcher'sshop.Sowhoshouldgettheblame?Therearemanyopportunitiesforforeignobjectstofindtheirwayintofood.

Sometimesthethinggetstherebyaccidentandsometimesitisfromdeliberatetampering.

downandleadtospoilingarenotusuallythesameoneswhichpoisonpeople.(Asmentionedearlier,notallmicroorganismsarebadforus.)However,thesamefactorswhichallowfoodtoharmlesslyspoilmightalsoprovideanopportunityforpathogenstocontaminatethefoodandmultiply.Inanyevent,itisnotagoodideatoeatfoodwhichhasspoiled.

Inmanycasestherearenoobvioussignsofbacteriaandvirusesatworkinfoodanddrink,soyoucannotalwaysrelyonwhatyoursensesaretellingyou.However,insomecasesthechangesshowthemselvesinonewayoranother.

ForeignBodies

Youshouldalsowatchforforeignbodies,suchaswormsorinsectsinrice,flouranddriedfoods.Thesedonotleadtofoodspoilageinthesenseofmicroorganismactivity,buttheycanadverselyaffectthequalityandpalatabilityoffood.

Aforeignobjectcancauseagreatdealofphysicalandemotionaltrauma.Apoison,ofcourse,mayevenbefatalifswallowed.Morecommonly,however,wehearoffragmentsofbrokenglassorwire:awiresievemaywear

throughandfallapart,aglassjarmightshatterunderstress.

Wheredoforeignobjectscomefrom?Thereareasmanysourcesasthereareobjects:

stones,dirtandsoilfromthefields

timberfrompalletsandboxesusedtocarttheproduce

glassandmetalfromprocessingmachinery

glassfromlightbulbsandlightfittings

asbestos,fibreglassandotherbuildingmaterials

bonefragmentswhichhavesurvivedthefoodprocessingintact

plasticfrompackaging

jewellerypins,birosandotherpersonaleffectslostbystaff.

Forconsumers,thesethingscanleadtocuts,choking,brokenteeth,infection(resultingfromcuts),aswellasillness(fromdirtbornebacteria).

HowDoYouProtectYourself?

Ifwecannotgenerallypickapotentiallyharmfulfoodusingoursenses,howdoweprotectourselves?Unfortunately,therecanbeno100percentguaranteesofsafetyunlessyouhavealaboratorytestallyourfoodbeforeyouconsumeit!Foodsafetyawarenessisamixof:

whatcausesfoodpoisoning

howwegetit

therawmaterialsinthefood

whatyoursensestellyou

whereyouboughtthefood

howtheshopshadstoredthefoodbeforeyougotit

howthosewhodeliveredthefoodtotheshopshadhandledit

howyouhavebroughtthefoodhome

howyoustoredthefood

howyoupreparedorcookedthefood.

Wewilldiscusstheseissuesinthechaptersthroughouttherestofthisbook.

USEYOURCOMMONSENSES

Sense Signs

Sight(colourchange) Greensporesofpenicilliumoncheeseorbluewhiskersonbreadwhitewhiskersonzucchinigreenpatchesonpotatoesdarkspotsonmeatblackspotsonbananas,applesandtomatoessilverycolouronmeat.

Sight(damagedpackaging)

Canswhicharedented,rustyorhaveswollenendsmilkandotherdrinkcontainerswhichhaveblownoutopenorleakingcontainers.

Smell Foulodoursfromgasproductionandbacterialbreakdownsoursmellingmilkacrid,ammoniaor'wetcardboard'smells.

Touch Sticky,viscous,'ropy',slippery,slimy(forexample,lettucemeat,ham),hollow,softandsquishy(vegetablesandfruit).

Taste Sour,unpleasant,overpoweringnothowitusuallytastes.

Summary.

Checkthenewspapersandwatchthetelevisionnewsregularlysothatyouareawareofanyfoodrecallsorotherhealthrisksinyourcommunity.

Rememberthatfoodsafetyproblemsdon'tjuststrikesmallmanufacturerssometimesthebigbrandshaveproblemstoo.

Useyoursensesandexperiencetohelpdetectwhetherfoodis'off'.However,beawarethatyoursenseswon'thelpyoudetectallharmfulchangestofood.

Justbecauseafoodhasgone'off'orspoileddoesn'tautomaticallymeanifyoueatityouwillgetsick.

Chapter2KnowYourEnemy!

Ifwecannotalwaystrustoursensesandexperiencetowarnusoffoodswhichmayharmus,whatcanwedotoimprovetheposition?.Thepositivemessageofthisbookisthatyoucanreduceyourriskoffoodpoisoningbyknowingalittleaboutthewaythepathogensworkandthefoodstheyliketocontaminate.

Thischapterintroducesthebadguysthebacteria,viruses,toxins,yeasts,mouldsandnaturalpoisonswhichgiveourfoodsupplysomuchtrouble.Alongthewayyouwillpickuptipsthatwillhelpyouindailylivingandeating.

Bacteria

Bacteriaaretinylivingthings:microorganisms.Theyarebasic,singlecellcreatures,andaresosmallaroundonemillionthofametreindiameterthatyoucannotseethemwiththenakedeye.Theycomeinavarietyofshapes.Themostcommonofwhichlookabitlikearod('bacillus'),comma('vibrio'),ball('coccus')orspiral('spirillum').Somehavemanylittlelegs('flagella')whichhelpthemmovearoundiftheyareinaliquidofsomekind,butmostbacteriacan'tmovethemselves.Theygetaroundthankstothewindorbyhitchingarideonpeople,animalsandinsects,orinfood.

Asawayofgettingtoknowbacteriabetter,let'stakeacloserlookatoneofthebetterknownones:Salmonella.IntheUnitedStates,Salmonellaisoneofthemostfrequentlyreportedcauseoffoodborneillness.TherearemanydifferenttypesofSalmonella,buttwo(called'serotypes')accountforabouthalfofallcasesofsalmonellosis:SalmonellaenteritidisandSalmonellatyphimurium.Salmonellalivesintheintestinesofwarmbloodedanimalsandinsects,andtheirfaecescanalsocontainSalmonella.Humanscanbecarriers,sometimesshowingnoilleffects,butabletopassSalmonellaontoothers.AnimalswhichharbourSalmonellaincludechickensandcattlethepestswhichinvadeourkitchens,suchascockroaches,flies,ratsandmiceaswellasthefamilydogsandcats.

InfectionwithSalmonellacanresultinlongtermillness(suchasreactivearthritis)andsepticaemia.Insomepeople,particularlytheelderly,Salmonellainfectioncanbefatal.AfewwilldevelopReiter'ssyndrome.Thisillness,whichhassymptomsincludingeyeirritation,jointpainandpainfulurination,cancontinueformonths,evenyears,andmayleadtoterriblearthritis.

FoodswhichhaveaparticularconnectionwithSalmonellainclude:meat,eggs,icecream,cheese,milk(raworpasteurised),pate,hamanddrinkingwater.TherearethreemainwaysinwhichSalmonellamakesitswayintoourbodies:

directcontaminationfromanimalfaeces

contaminationfrompeoplewhodon'twashcarefullyaftergoingtothetoilet

crosscontaminationfromrawfoodstocookedorotherwisecleanfoods.

Whenanimalsareslaughteredforfood,theSalmonellapresentintheirintestinescan,throughcontact,contaminateotherpartsoftheanimalcarcase,includingthebitspeoplewilleat.Animalfaecesmaycovereggsfromchickens,ducksandthelike,andmicroorganismsinthefaecescanbeabsorbedthroughtheeggshelltocontaminatetheeggitself.Duringthemilkingprocessacow'sfaecescancomeincontactwiththemilkandcontaminateit.Inplainlanguage,whatwe'retalkingabouthereissomesortofpathwaybetweenSalmonellainananimal'sintestineandcontactwithrawfoods.

Thesecondpathwayissimilar:itistheproblemoftracesofhumanfaecesgettingontoaperson'shands,usuallyatthetoilet,andhandlingkitchenutensilsorfood.

ThethirdrouteforSalmonellatoaffectfoodistopassfromacontaminatedrawfooduncookedmeatormilktootherwise'clean'food,suchassaladorvegetables.Thistypicallyhappensifthecookusesthesamechoppingboardforrawmeatandthevegetables,orthesameknifesandutensils.Thisisthereasonwhyitisrecommendedyoukeepandusedifferentchoppingboardsforrawmeat,cookedmeat,andvegetablesandsalad.Alternatively(butitisharderwork)youcancleanandsanitisetheboardbeforeitisusedagain.

ReproducingTrouble

Bacteriareallybecomeaproblemwhentheyreproduce,andthiscanhappenveryquicklyinfood.Initiallythereisa'lag'stagewhenthebacteriagetusedtothenewfoodtheyfindthemselvesin.Thisprocesscouldtaketwoorthreedays,oraslittleasacoupleofhours.Then,onceadaptedtotheplace,andundertherightconditionsoftemperatureandlocation,eachcelldividestoformtwocellsevery20minutesorso.Thismeansthatifyoustartwith,say,10,000bacteria,itwilltakelessthantwohoursand20minutes(plusthelagperiod)toreachmorethanonemillionbacteria.Therearelargevariationsinthenumberofmicroorganismsnecessarytocausefoodpoisoning.ResearchrevealsthatsomemicroorganismscancauseharminverysmallnumbersSalmonellaandShigella,forexample.TherearedocumentedoutbreakswheretestsshowedonlyoneSalmonellaorganismpergramoftheaffectedfood.

Timeisakeyissueinprotectingyourselffromfoodpoisoning.Ingeneralittakesbetweenfourandsixhoursforbacteriatoreachsufficientnumberstomakeapersonill.Largernumbersmeanthereisagreaterlikelihoodthatenoughwillsurvivetobeeatenitalsomeanstheincubationperiodcanbeshorter.However,thelagstagecouldextend

TIPKeepfoodsoutofthetemperature'dangerzone'ofbetween5and60C(40140F).

formanyhoursordaysafterthefoodfirstbecomesinfectedwiththebacteria.Itwon'talwaysbeaquickprocess.

Secondly,theconditionsunderwhichthebacteriafindthemselvesarealsovital:theywilldivideandgrowmoreslowlyiftheconditionsareunfavourable.Ifyouknowwhatmakestheconditionsfavourableyou'reonthewaytoknowinghowtomakelifehardorimpossibleformanytypesoffoodpoisoningmicroorganisms.

Idealconditionsforbacteriagrowthare:

atemperaturerangeof560C(40140F).Thepaceofbacterialgrowthreallypicksuparound3032C(8687F).

anenvironmentwhichismildlyacidicorneutral(measuredasapHof4.5to7).Alkalineorveryacidicfoodsinhibitmostbacterialgrowth.Moulds,however,canbequitehappyinveryacidicfoodslikefruitjuice.

plentyofnutrientsforthebacteria.Bacteria,aslivingorganisms,needtheirownfoodtosurvive.Clearlythen,theycaneitherstarveorthriveaccordingtothenutrientsavailableintheirlocation.Bacteriapreferfoodscontaininglotsofprotein:likemeat,dairyproductsandeggs.Deprivethemofproteinandtheyfindthegoingtough.

moistratherthandryconditions.Youdon'tusuallyfindlargenumbersofbacteriagrowinginhouseholdfoodslikeflourorcustardpowderwhilesittinginthecupboard.However,onceyoumakeupthecustardorpowderedmilk,itprovidesawonderfulhavenforbacteriatogrow.Moisturecanbefoundeitherinthefooditselforintheplacewherethefoodislocated(thekitchen,pantryorcarboot).Anatmosphereofhighhumiditypromotesbacterialgrowthdryconditionsslowitdown.

air,orlackofit,Somebacterianeedoxygen('aerobic'bacteria),othersprefertoavoidit('anaerobic'bacteria),whileathirdtype('facultative'bacteria)doesn'tmindwhetherthere'soxygenornot.

BetweenHotandCold

Oneofourbesttoolsforfightingfoodbornediseaseiscontrolovertemperature.Microorganismsshutdownwhenitistoocoldandarekilledwhenitgetstoohot.Whiletherearesomeexceptionstothisrule,youwillgreatlyimproveyoursafetyifyoukeepyourfoodatsafetemperatures.Keepfoodsoutofthetemperature'dangerzone'between560C(40140F).Bacteriapositivelythriveataroundhumanbodytemperature,andonhotsummerdays.

BacterialToxins

Noteverycauseoffoodpoisoningisalive.Thegreatexceptionsarevariouspoisonsortoxinsproducedbybacteria.Thebacteriathemselvesmightcomeandgo,living,reproducing,dyingorfreezingintoinaction.Butthetoxinstheyreleasepaynoheedtothevariousconditionswhichmightstopamicroorganismdeadinitstracks.

Whathappensisthis:bacteriagrowinsideafood.Atacertainpointthebacteriareleaseatoxin.Somebacteriareleasetheirtoxinintothegutafterthefoodhasbeeneaten,whilesomedothisbefore.Withthesebacteriaitisthetoxinthatmakesthepersonsick,notstrictlythebacteria.Butthebacteriaareneverthelessdangerousforhavingthistoxicability.

SomeofthebacteriawhichproducedangeroustoxinsincludeBacilluscereus,Clostridiumperfringens,Escherichiacoli(E.coli)andStaphylococcusaureus.Somemouldsproducepoisonsknownas'mycotoxins'.Thesecanbefoundinmanytypesofgrainsandnuts,includingpeanuts,maizeandwheat.Suchmycotoxinscancausecancerorotherseriousillnessinhumansifcontaminatedfoodsareeatenoveraperiodoftime.

THEACIDTEST

Microorganismsalsodonotlikebeinginfoodwhichiseitherstronglyacidicorstronglyalkaline.Theypreferfoodswhicharemildlyacidicorneutral.AcidityismeasuredbythepHlevelonascalefrom0to14.

IfyouownandmaintainaswimmingpoolyouwillbefamiliarwiththeneedtokeepthepHintherightrange,wherethewaterisclean.OncethepHmovesoutofthatrangeitdoesnottakelong,duringthesummerheat,foralgaetogrow,turningthewatergreenand,eventually,almostblackincolour.Itissomethingsimilarforbacteria.

Oneofthewayswetryandcontrolthegrowthofmicroorganismsisbymanipulatingtheacid/alkalicharacteristicsoffood.Forexample,jamsandmostpreservesareacidic.

AEROMONASSPP.

Whatisit? Bacteriawhichproducestoxinsoncethefoodhasbeeneaten.

Signsandsymptoms: Diarrhoea,abdominalpain,dehydration.

Timetosicknessafterconsuming. 648hours.

Illnesslasts: 17days

Favouritefoods: Seafood,shellfishandrawfoodsofanimalorigin.

Howdiditgetthere? Contaminatedwater,commonlyfromsinksanddrains.

Protectionstrategy: Cookingreadilykillsthesebacteria.

BACILLUSCEREUS

Whatisit? Abacteriumwhichcanproduceenterotoxins(toxinsabsorbedintheintestine).

Signsandsymptoms: Diarrhoea,abdominalpain,nausea,vomiting,sometimesfever.

Timetosicknessafterconsuming: 816hoursforthe'diarrhoeal'toxinand16hoursforthe'vomiting'toxin.

Illnesslasts: 1214hours(heatunstabletoxin)624hours(heatstabletoxin).

Favouritefoods: Cerealslikecorn,previouslycookedrice,pasta,potatoes,sauces,puddings,cookedvegetables,vegetablesprouts(forexample,mungbean),meat,meatloaf,icecream,freshorpowderedmilk,custard,coldsoups,puddings,commercialbattermixes,spices,sauces.

Howdiditgetthere? Foodborne,soil,airandwater.

Protectionstrategy: Keepfoodsoutofthetemperaturedangerzone.

CAMPYLOBACTERJEJUNI

Whatisit? Abacteriumwhichcanproduceatoxin.

Signsandsymptoms: Diarrhoea,vomiting,fever,tirednessandabdominalpain.

Timetosicknessafterconsuming: 25daysormore.

Illnesslasts: Lessthan7days.

Favouritefoods: Rawandundercookedchicken/poultryandhamburgermince,cakeicing,water,processedturkey,rawclams,eggs.

Howdiditgetthere? Faecalcontaminationandpoorhandlingcontaminatedwater.

Protectionstrategy: Cookingandprocessingtechniquessuchassalting,acidandheat.

CLOSTRIDIUMBOTULINUM

Whatisit? Abacteriumwhichcanproduceatoxin.

Signsandsymptoms: Weakness,dizziness,extremethirst,doublevision,vocalcordparalysis(can'tspeak),paralysisofdigestivesystem,heartandlungs,uncontrollableconvulsions,tetanuslikesymptoms.Canleadtodeath.

Timetosicknessafterconsuming: 1236hours.

Illnesslasts: Severalmonths.

Favouritefoods: Homebottledvegetablesandfruitslowacidornonacidiccannedfoodssuchastunafermentedfoodsmushroomssoupandsmallgoodssuchascannedmeatvegetablesfishandsalamisalmoneggsgarlicinoilbakedpotatoesvacuumpackedfoodslikelotusrootssmokedfish.

Howdiditgetthere? Fromsoil,dust,waterandair,intestinaltract.

Protectionstrategy: Boiling.Adequateheatingofcansandcontents(100Cor212Fforsevenhours)fixesmostcases,althoughsporesrequirelongerheating.Commercially,acidityisatoolusedtocontrolitasthebacteriadoesnotgrowwherethepHisbelow4.6.Commercialcanneriesalsousehighertemperaturesandshortertimes(forexample,at121Cor250Ffor15minutes)toensurethatsporesaredestroyed.

CLOSTRIDIUMPERFRINGENS

Whatisit? Bacteriawhichproducesporeswhich,upongermination,produceatoxinintheintestine.

Signsandsymptoms: Diarrhoea,stomachcramps,headachevomitingisrare.

Timetosicknessafterconsuming: 624hours

Illnesslasts: 1224hours.

Favouritefoods: Largepiecesofmeatsuchasporkandrolledroasts,casserolesandmeatgravies.

Howdiditgetthere? Anaturalcontaminantofmeatandfoundinsoil,dust,waterandsewage.

Protectionstrategy: Cookyourfoodinsmallerbatches,ensuringthefoodisheatedthoroughly.Rapidcooling:donotleaveleftoverstocoolslowly.Putleftoversinthefridgeorfreezerinsmallservessotheycoolmorerapidly.

ESCHERICHIACOLI(E.COLI)

Whatisit? Bacteriacapableofcausingfoodborneillnessbyarangeofmechanisms.

Signsandsymptoms: Diarrhoea(maybewaterythenbloody),dehydration,headache,abdominalcrampsandpaincanleadtodeath.

Timetosicknessafterconsuming: 38days.

Illnesslasts: Severaldaystomanyweeks,dependingoncomplications.

Favouritefoods: Meats(particularlybeefbutalsochicken),dairyfoodslikemilkandsoftcheeses(particularlyifunpasteurised),mincedmeat,fermentedsalamisandsausages.

Howdiditgetthere? Crosscontaminationattheabattoirorathomenotwashinghandsaftergoingtotoilethandlingrawmeatandpassingthebacteriaacrosstocookedfoods.

Protectionstrategy: Sometypescansurviverefrigeratorandfreezertemperaturesandsomehavedevelopedresistancetoantibiotics.Cooking,washinghandsandavoidingcrosscontaminationinthekitchenhelp.

LISTERIAMONOCYTOGENES

Whatisit? Bacteria.

Signsandsymptoms: Headache,fever,nausea.Canleadtomeningitis,septicemiaanddeath.Itcanbeespeciallydangeroustoagedpeople,pregnantwomen(spontaneousabortionorstillbirthpossible),andpeoplewithcanceroracompromisedimmunesystem(canleadtoarthritis,braindamageandvariousinternalinflammations).

Timetosicknessafterconsuming: Approximately3weeks.

Illnesslasts: Varies,dependingoncomplications.

Favouritefoods: Highproteinmoistfoodssuchaschickenandsoftcheese,unpasteuriseddairyfoods,pate,fermentedsausage,rawfish,leafyvegetables,salads(forexample,coleslaw),smokedmussels.

Howdiditgetthere? Fromanimals,soil,water,sewage,cropsfertilisedwithsewage.

Protectionstrategy: Cookingto70C(158F),ensuringthateventhecentreofthefoodreachesthistemperature.Cangrowatrefrigeratortemperatures,butiskilledbyshortwaveultravioletlight.

Anoutbreakoflisteriosis,whichoccurredinFrancein1992,wastracedtoconsumptionofjelliedporktongues.Therewaswidespreadillnessleadingtothedeathsof63people.InastartlinreminderofthespecialriskListeriamonocytogenesposestopregnantwomen,thisoutbreakresultedin22miscarriages.

SALMONELLA

Whatisit? Bacteria.

Signsandsymptoms: Nausea,fever,diarrhoea,stomachcrampsanddehydration,sometimesfeverandchills.Canleadtomeningitis,pneumoniaordeathinelderlyorsickpeople.

Timetosicknessafterconsuming: 1224hours,average18hours.


Favouritefoods: Highproteinfoodssuchaschicken,turkey,shellfish,meat,eggs,rawvegetables,unpasteurisedmilk,andincompletelyreheatedlarge,frozenorrefrigerateddishesofhighproteinfood(e.g.fromthemicrowaveoven).

Howdiditgetthere? Faecalcontaminationfromanimals,humans,birds.Poorhandling.Itcanbecarriedbyfliesandotherinsects.

Protectionstrategy: Cookingto70C(158F)for10minutes.

SHIGELLA

Whatisit? Bacteriaanditstoxin.

Signsandsymptoms: Diarrhoea(sometimesbloody),vomiting,fever,abdominalpainandacontinualfeelingofneedingtogotothetoilet.

Timetosicknessafterconsuming: 17daysbutgenerally14days.

Illnesslasts: 47days.

Favouritefoods: Beans,milkproducts,rawvegetables,salads(e.g.tuna,potato,prawn/shrimpsalads),wellwater.

Howdiditgetthere? Spreadbypersontopersoncontact,foodandpersonalhygiene,water,fliesfaecesofinfectedpeople.

Protectionstrategy: Goodpersonalhygienewillreduceriskofinfectionwashfruitandvegetableswithtreatedorboiledwaterchildrenareahighriskgroup.

STAPHYLOCOCCUSAUREUS('GOLDENSTAPH')

Whatisit? Abacteriumwhichproducesatoxin.

Signsandsymptoms: Vomiting,diarrhoea,stomachcramps,headaches,chills,fever,weakness.

Timetosicknessafterconsuming: 16hoursbutgenerally23hours.


Favouritefoods: Hamanddelimeats,custard,cream,cheese,milk,prawns/shrimp,smorgasbords,saltyandsugaryfoods,lowacidcannedfoodspotatosaladsoffish,poultry,hamorpotatoextendedshelfliferefrigeratedfoodsandmodifiedatmospherefoods.

Howdiditgetthere? Carriedinnoseandfacialhair,onhandsandbyunhygienichandling.Watchforinfectionsonhandsofpeoplehandlingfood,orfoodpreparerswithcolds/flu,runnynose,pimples,acne,burns.

Protectionstrategy: Heatingto70C(158F)for30minutes.

VIBRIOCHOLERAE

Whatisit? Bacteriaproducingatoxin('cholera'istheillness).

Signsandsymptoms: Diarrhoea(sometimesbloody),vomiting,nausea,severedehydrationcanleadtosepticaemiaordeath.

Timetosicknessafterconsuming: 6hoursto5days.

Illnesslasts: Uptoseveraldays.

Favouritefoods: Rawseafoodsincludingprawns/shrimp,crabandoystersindevelopingnations:water,iceandfoodsrinsedinwater,suchasvegetablesandrice,softdrinks.Grainsandlegumesgrownincholeraendemicareas.

Howdiditgetthere? Humanfaecescontaminatingfoodandwater.

Protectionstrategy: Cookingkeepingsewageawayfromfreshwater.

VIBRIOPARAHEMOLYTICUS,V.VULNIFICUS,V.MIMICUS,V.HOLLISAE&V.FUNISSII

Whatarethey? BacteriaofseveralspeciesintheVibrio(cholera)family.

Signsandsymptoms: Diarrhoea(canbebloody),abdominalpain,cramps,vomiting,headache,nausea,chillsandfevercanleadtodeath.

Timetosicknessafterconsuming: 4hoursto5days,dependingontype.

Illnesslasts: 36days.

Favouritefoods: Raworundercookedseafood,particularlyoysters,shellfish,clams.

Howdiditgetthere? Theyarenaturallyoccurringintheseaandmaybelinkedtosewagecontamination.

Protectionstrategy: Cookinganddryingcansurviverefrigerationandfreezing

YERSINAENTEROCOLITICA

Whatisit? Bacteriaanditstoxin.

Signsandsymptoms: Strongabdominalpain,diarrhoea,canleadtoulcerationofthecolon,dermatitis,lymphsysteminflammation,septicaemiaandarthritis.


Illnesslasts: 12daysbutcanlastweeks.

Favouritefoods: Dairyproductswherepasteurisationhasbeenineffectiveorcontaminationhasoccurredafterpasteurisation,water,icecream,powderedmilk,chicken,vacuumpackedmeat,pigmeats,seafood.

Howdiditgetthere? Contaminationbyanimalfaecesafterthefoodprocessingstage,poorhandlingoffood.

Protectionstrategy: Coldisineffective:itcangrowatrefrigerationtemperatures.Cookfoodsto75C(167F).

Viruses

Apartfrombeingthesmallesttypesofmicroorganismsaslittleasonehundredththesizeofsomebacteriavirusesareunlikebacteriaandfungiinthattheycanonlyreproduceoncetheyhavemadetheirwayinsidelivingcells.Theydonotgrowandincreasetheirnumbersinsidefood.Foodissimplyaveryneatwayforthevirustomovefromoutsidetoinsideabody,whereitworksitswayintothecellsandcanthenreproduce.Oncetheviralnumbersreachasufficient'dose',thehostbecomesill.

Whenasickpersonvomits,coughs,sneezesorspits,theyspreadviralparticlesbythemillionsintheirsaliva,possiblypassingthemtoothernearbypeople.Virusescansurviveonyourclothing,getpickeduponyourhandsandpassontothefoodyouarepreparing.Extracaremustbetakenwhencaringforyoungchildrenandinvalids,asurineandfaeces,itshouldbenoted,canalsospreadviruses.

Itisestimatedthatvirusesarethecauseofaround10percentoffoodborneillnessesinAustralia.SomeevidencefromtheUnitedStates,however,placesthefigurecloserto35percent.Twoexamplesofviralillnessesaregastroenteritisandhepatitis.

Themaintroublespotswithfoodbornevirusesincludemolluscs,rawfruitandvegetables,andoftenhandledfoodssuchassaladsanddesserts.Molluscshellfishsuchasoysters,musselsandcocklesmaybecontaminatedfromsewageinthewaterinwhichtheygrow,oftencoastalorestuarinewatersorriversintowhichsewageisdumped.Theshellfishactasfilters,leadingtoaconcentrationofthevirus.And,ofcourse,suchshellfishareofteneatenraworwithminimalcooking.

Fruitandvegetableswhichareservedrawcancarryvirusespickedupfromirrigatingorfertilisingthemwithsewageorsewagecontaminatedwater.Iftheyarenotthencooked,theviruscomesstraightfrom

CHOLERA:THEEPIDEMICTHATWON'TDIE

EpidemicsofcholerahavesweptthroughEurope,AsiaandAfricaforhundredsofyears,killingmillionsofpeopleandcripplingtheirsocieties.Andthen,quitesuddenlyintheearly1900s,theillnessappearedtodieoutindevelopednations.Bythistimeweknewhowtoconstructbettersewersandtheimportanceofmaintainingapurewatersupplyfordrinkingandcooking.Inthepoorernations,however,choleracontinuedtoclaimlivesthroughoutthecentury.

ButcholeracontinuestoappearevenincountriesliketheUnitedStates.In1973therewasacaseofcholerainTexasfiveyearslater11peopleinLouisianacamedownwithitandanother12in1986andmoreintheearly1990s.Theriskissmall,however,indevelopednations.ButbeextracarefulwhentravellinginCentralandSouthAmerica,Africa,Asiaandinanycountrywithpoorlyperformingwaterorsewagesystems.

thepaddocktoyourplate.Withfruitandvegetables,unlikeshellfish,theviruswillbefoundonthesurfaceofthefoodwhereitishighlysusceptibletoheattreatment(cooking).

Saladsanddesserts,whichoftenrequiremuchhandlingbychefsandkitchenstafftogetthemintotherightshape,mayalsoeasilybecontaminated.Again,saladsanddessertsreceivelittleornocookingaftertheyhavebeenhandled,whichisaperfectopportunityforavirustopasswiththefood.

Virusesposeaparticularproblembecause:

thereisnosimplemeansofdetectingtheirpresenceinfood

unlikemostbacterialproblems,itdoesnottakealargenumberofvirusparticlestopassillnesstoaperson

acookorwaitermighthavebeencontaminatingfoodfordaysbeforeshowingthefirstsymptomsofillnessthemselves

virusesaretough.Theycanresistchilling,freezing,preservativesandionisingradiation,aswellasacidicfoodsandpicklinginvinegar.

Fortunatelyvirusescanbekilledquicklybyheatingfoodto85C(185F).Youshouldunderstandthatyouaretakingabiggerviralriskwithrawfoods,especiallyshellfish(seeChapter8).

HEPATITISA

Whatisit? Virus.

Signsandsymptoms: Fever,vomiting,malaise,lossofappetite,followedbyjaundice.Deathisrarebutmayoccur,particularlyintheelderly.Symptomsdevelopgraduallyandareusuallymoresevereinadultsthanchildren,

Timetosicknessafterconsuming: 36weeks.

Illnesslasts: Uptoseveralmonths,dependingoncomplications.

Favouritefoods: Oysters,prawns,molluscs.

Howdiditgetthere? Persontopersontransmission.Itcomesfromthehumanintestine,passingbypoorfoodhandlingorbycontactwithcontaminatedwater(forexample,thesewagepollutedwaterinwhichtheoystersgreworwereheldcropirrigation).

Protectionstrategy: Personalhygieneavoidinghighriskfoods.

NORWALK

Whatisit? Virus.

Signsandsymptoms: Suddenonsetofvomiting(maybeprojectile),explosivediarrhoeaandabdominalpain.

Timetosicknessafterconsuming: 1572hoursbutgenerally2436hours.

Illnesslasts: About3days.

Favouritefoods: Orangejuice,water,oystersandsalads.

Howdiditgetthere? Persontopersontransmission,comesfromhumanintestine,poorfoodhandlingorbycontactwithsewagecontaminatedwater.

Protectionstrategy: Useonlytreatedwaterorboiledwaterforwashingsalads,foodpreparationanddrinkingavoidrawseafood.

YeastsandMoulds

Yeastsandmouldsarelivingmicroorganisms,likebacteria.Yeastscanmakefoodgo'off',accompaniedbybubbling,sometimesslime,andanaromasomethinglikebeerorwine.Thereareusefuland'good'yeasts(suchastheonesusedwhenbreadismadeorbeerisbrewed),aswellasbadyeaststoavoid.Yeastsarenotusuallyassociatedwithfoodpoisoning:onlyfoodspoilage.

Mouldsareamongthemostobvioustypesoffoodspoiling.Youhaveprobablyseentheirspidery,bluegreenpowderonoldbreadontheskinsofrottingorangesonthetopofjamsandpreservesoronthesideofablockofcheese.Theirsmellcanbepungent,likeawetdogorawetcardboardbox.

Infactonsomefoodsyouaremorelikelytofindmouldsratherthandangerousbacteria.(Generally,bacterialikeawetfoodwithplentyofmoisturetohelpthemmovearound.Oneofthewaystocontrolbacterialgrowthisbydryingtheproduct,forexample,thecuringofham.)Mouldswillhappilygrowatmuchlowermoisturelevels.Theyturnuponfoodslikenuts,grains,peanuts,cereals,bread,cheeseandjams.

Moulds,likesomeferns,spreadbyforming'spores'whichblowawaytocoverotherpartsofthehostfood,eventuallygrowingtomaturityandproducingfreshspores.

Themouldwehaveheardmostaboutinthemediaistheoneassociatedwithpeanutsandpeanutbutter.ThemouldAspergillusflavusgrowsnaturally,inthefieldorevenafterthecrophasbeenharvested,andcanproduce'aflatoxin',mostcommonlyinpeanutandcorncrops.Themouldproducesthetoxininitshighestandmostdangerouslevelsinyearsofdroughtorothertraumawhichhasdamagedthosecrops.

Foodstandardsplaceanupperlimitontheamountofaflatoxinwhichispermittedinpeanuts(notmorethan15partsperbillioninAustralia),andmostmanufacturershaveequipmenttodetectit.However,whoischeckingthepeanutsinsmallhealthfoodshops(whereyoucangrindyourownpeanutpaste)orinlocalstreetmarkets?

Anotherfamoustoxinproducedbyamouldispatulin,whichturnsupinapple

ASPERGILLUSFLAVUS

Whatisit? Mouldthatproducesaflotoxins.

Signsandsymptoms: Largeexposurescanproduceabdominalpain,swellingduetofluidretentioninbodytissues(oedema),liverdamage,hepatitiscanleadtolivercancerandimpairedimmunesystem.

Timetosicknessafterconsuming: Severaldaysorevenyears,dependingondose.

Illnesslasts: Canbelongtermillness.

Favouritefoods: Peanuts,peanutbutter,peanutoil,corn,nuts,figs,cocoabeans.

Howdiditgetthere? Naturalmouldonthecrop,particularlyindroughtconditions.

Protectionstrategy: Governmenttestingofcrops.

juice,organicciderandfruitssuchasmouldyapples,apricots,cherries,grapes,peaches,pearsandplums.Studiessuggestitmaybeacarcinogen.(However,don'tconfuseamouldytasteorodourwiththesafebutsour,vinegarliketastethatfruitjuicesacquire.Thissourness,whichindicatesfermentationistakingplace,isnotahazard.)

Whatshouldyoudowithmouldyfoods?Inmostcases,throwthemawayorputtheminthecompost.(SeealsoChapter10.)

Parasites

Bacteriaandvirusesarearguablywhatmostpeoplethinkaboutwhentheyturntheirmindstofoodborneillness.Whilethesearethemostcommoncausesoffoodpoisoningthereareotherproblemswhichcomewithfood.

Tapeworm,roundwormandflukesaretypesofparasiteswhichliveinsidecattle,sheep,pigs,fishandthelike,andcanalsobefoundinvegetableswhichhavebeenirrigatedorfertilisedusingsewagecontaminated

CRYPTOSPORIDIUMPARVUM

Whatisit? Protozoan.

Signsandsymptoms: Profuse,waterydiarrhoea,abdominalpain,vomiting,lowgradefever,weightloss,lossofappetite,anorexia.Itcanleadtodeathinsomepeoplewithlowimmunity.


Illnesslasts: 23weeksbutcanlast6weeks.

Favouritefoods: Waterusedfordrinking,foodpreparationorforswimmingrawmeat(particularlysausagesandoffal),unpasteurisedmilk,fruitandvegetables.Itcanpassfrompersontopersoninplaceslikechildcarecentres.

Howdiditgetthere? Fromliveanddeadanimals,persontopersoncontact,contaminatedrawfoodsandthewatersupply(arguablyfromfarmandwildanimals).

Protectionstrategy: Specialfiltrationofwatersupplyitresistschlorinetreatment.Itisinactivatedbydryingheat,suchascookingorboiling,andbyfreezing.

GIARDIALAMBLIA(ORGIARDIADUODENALIS)

Whatisit? Protozoa.

Signsandsymptoms: Diarrhoea,weakness,nausea,excessivesmellysulfurousburps,wind.


Illnesslasts: Afewdaystoafewweeks.

Favouritefoods: Water

Howdiditgetthere? Itisfoundwidelyinnaturefaecalcontamination.

Protectionstrategy: Filtrationanddisinfectionofdrinkingwateruseofbottledwaterboilwaterforoneminuteandallowtocool.Donotwashsaladsinuntreatedwater.

water.Oftenthisismoreaproblemindevelopingnations.

Parasitesaboundinnature,butoftenourproductionpracticesmaketheproblemworse.Inaquaculture(anemergingindustrywherefish,oftenforsushi,areraisedintanks)theenvironmentcanbecontrolled.Unfortunatelyaquaculture,throughitscreationofamonoculturalenvironment,mayactuallycontributetothespreadofpathogenssincemanycompetingorganismshavebeenremovedfromthefoodchain.Someaquacultureavoidsthisbyusingoceanpens.

Iffoodisservedraworundercookedsushi,sashimi,rawbeefslices,salmonandsoontheparasitescansurvivethekitchenandpasstothediner.Onceinside,theyheadforplacesliketheliver,intestineorlung,wheretheygrowandcauseproblemslikemalnutrition,hungerpains,increasedappetite,musclepain,headache,vomiting,respiratoryproblemsandconvulsions,dependingonthetypeofparasiteandtheageoftheperson.

Thereisaparasitewecanacquirefromhandlingrawmeat,orfromcats.Toxoplasmagondiicanbepickedupifwehandleorcomeincontactwithinfected,stalecatfaeces(inthegarden,forexample),givingussymptomssimilartoaboutoftheflu(called'toxoplasmosis').Generallythesymptomspassquickly.Butpeoplewithlowimmunity,orpregnantwomen,shouldbemorecarefulandweargloveswhenpreparingrawmeat,gardeningorhandlingkittylitter.Indeedifthemothergetsinfectedthebabymightbebornwiththeparasitewhichmightinterruptthenormaldevelopmentofthechildatsomestage.Peoplewithreducedimmunitycanbecomeblindor,intheworstcases,mightdiefromtoxoplasmosis.

Cookingkillsmostoftheparasiteswecomeacross.Freezingisnotalwaysaseffective.

AccidentalExtras

Youeatameal,yougetsick,youblamethebugs.Butyoumaybewrong.Thereareallsortsofchemicalswhichgetintothefoodsupply.Somearequiteharmless,whileothersbecomepoisonousiftheyarethereintherightamountoriftheygotintothefoodatasensitivetime.

Forexample,farmersusechemicalpesticidesandherbicidestocontrolweeds,diseasesandinsectpestswhichmightotherwisedevourorruintheircropsoffruitandvegetables.Werelyonsuchchemicalsforthewideandcheapavailabilityoftheseimportantfoods,althoughthedemandisgrowingforfruitandvegetablesthatare'pesticidefree'and'organicallygrown'.

AJanuary1999USDepartmentofAgriculturesurveyofpesticideresiduesinfoodfoundlowlevelsofresiduesin57percentoffruitandvegetablesamples,87percentofsoybean,80percentofwheatand15percentofmilksamples.Thesamplescamefromfoodsoriginatingin43statesoftheUnitedStatesand23foreigncountries,soitwasafairlylargepoolthatwassurveyed.Puttingthistogether,theresearchersfoundlowlevelbutwidespreadpesticideresiduesinasmanyas28foodseatenbyAmericans.Onequarterofthepesticideresiduesfoundinfruitandvegetableshadbeenaddedafterthefoodhadbeenharvested(forexample,whileinstorage,tokeeppestsatbay).Itisahugeissue,andonedaywemayhavedifferentideasaboutwhatallthesepesticidesaredoingtousevenatlowlevels.

Scientistsandchemicalmanufacturersknowthegenerallyaccepted'safe'dosesofthesechemicals,butthereisnothing(otherthantheirhighcost)tostoptheindividualfarmerusingtoomuchofthepoison.Educationaboutagriculturalchemicalsisessentialforfarmers,thoughitislackinginmanypartsoftheworld.

Asecondproblemoccursifthechemicalsareusedatthewrongtime.Themostobvi

ousdangeriswhenacropfindsitswayintotheshopsbeforethechemicalshavehadsufficienttimetobecomeharmless.Pesticidesandagriculturalchemicalshavewhat'sknownasa'withholdingperiod':aperiodofanumberofdaysduringwhichthefruitorvegetablesmustnotbeeatenasitmaybepoisonoustohumans.

Otherpoisonouschemicalswhichmaygetintofoodinclude:

leadandmercuryheavymetalsandotherpollutantsinthesea.

disinfectantsandcleaningchemicals,suchascausticsoda,usedinthefoodprocessingmachinerytocleanandsterilisetheworkplaceortheircontainers(suchasglassbottles)laterusedforfoodordrink.Benchtops,pots,pansandknivescanbecontaminatedinthesameway.

thecontaineritself,whichcanintroduceapoisonintothefood.Oneexampleisthetincoatingusedtopreventcorrosionofcans.Acidicfoodsmaydissolvesomeofthetin.

monosodiumglutamate(MSG),usedasaflavourenhancer.ItisastapleoftherestauranttradeandiswellknownforgivingthedineraterrificthirstaftereatingamealhighinMSG.TheremaybeothermoreseriousreactionstoMSG,suchasatypeoffoodallergyreaction,andasthma.However,theresearchisnotconclusive.Italsooccursnaturallyandathighconcentrationsintheskinsofsomefruits.

Summary.

Foodborneillnessmaybeduetobacteria,avirus,amould,fungusoranonlivingtoxinreleasedbyamicroorganism.Sometimesprotozoaareatfault.

Thereisoftenarelationshipbetweenparticularfoodsandparticularpathogens.

Werelyondifferenttoolsandtechniquestoneutraliseorcontroldangerousmicroorganisms.Thetechniquesareusuallysimpletoimplementeveninthehomeandhighlyeffective.

Chapter3WhoIsMostVulnerable?

Intrackingdownthecauseofaparticularboutoffoodpoisoning,itishandytoknowthatsomeillnesseshitcertainagegroupsmoreoftenorwithgreaterseveritythanothers.

Forexample:

theelderlyandtheunbornareatparticularriskfromListeria

forSalmonellaitischildrenagedunderoneyear

forCampylobacter,itistheonetofouragegroup

symptomsofGiardialambliaaremoresevereinchildrenthanadults

E.coli's'enterohaemorrhagic'formsappeartohavetheirmostprofoundeffectonyoungchildren,particularlyaroundtheageoffourorfive.

Children

NowherewastherealityofanagelinkseenmoreforciblythanintheGaribaldimettwurstincident(seepage49).Herewasasalamithatwaseatenbyadultsandchildren,yetalmostallthoseaffectedstronglybyfoodpoisoning(inthiscaseE.coli)werechildrenagedfromfourmonthsto12years,withmostcasesinagrouparoundfouryearsofage.Wedon'treallyknowalotaboutwhythishappens.Theconnectionshaveonlybeenpickedupbyresearcherswhoaddupthenumbersofreportedcases.

Onetheoryisthatchildrenhaveareasintheirlargeintestineswhichbindthebacteriaoritstoxin,whereasinadultsthesesiteshaveclosed.Accordingtothisview,thesereceptorsmayopenagaininoldage,helpingtoexplainwhytheelderlyareatheightenedrisk,oncemore,fromcertainbacteria.

'Itisacomplexsituation,largelyuninvestigated,'saysAssociateProfessorScottCameron,ClinicalAssociatewiththeDepartmentofHealthattheUniversityof

Adelaide,'Theremaysimplybeabiasinthesystembecausewerushofftothedoctorandgetthechildtestedbutnottheadult.'ProfessorCameronsuggeststwobroadreasonswhychildrenareoftenmoreaffectedbycertainpathogens.Firstly,thereistheideathateveryoneisexposedtothesepathogens,andwedevelopasymptomaticillnessatthetimeoffirstexposurewhenwearechildrenbeforedevelopingsomekindofimmunitythatprotectsuslaterinlife.

Secondly,itmaybethatveryyoungchildrenaremorelikelythanadultsandolderchildrentoeatcontaminatedfood.'Behaviouralaspectsmakeitmorelikelyforonegrouptobecomesick,'headds.Forexample,it'sthechildwhoismostlikelytolickthecakemixoutofthebowl,consumingsomeraweggatthesametime.

Parentsshouldalsobearinmindthatbacteriasurviveandgrowonthevariousbitsandpiecesofbabyfeedingequipment,frombottlesandteatstononspillcupswithnarrowopeningsorplasticstrawswhichcanbedifficulttoclean.Oftenthesethingsarenotsterilisedtheymayevenbouncearoundinsidethenappybag,pickingupbacteriaandmicrobesfromallaround.Littlechildrenalsolikeexploringtheirenvironment,therebyexposingthemselvestorisks.

Areweputtingnaturalimmunityatrisk?

IntheUnitedStateswinterof1997,sevenchildrenacquiredapathogenicstrainofE.colifromadaycarecentreinSpokane,Washingtonfromplayingwithcontaminatedmodellingclay,toys,sandandsoil.AnotherpathogenicE.colioutbreak,thistimeinAtlantaGeorgia,saw26childrencomedownsickafterplayinginapoolatthelocalwaterparkonechilddevelopedkidneycomplicationsanddied.Aleakingnappywassuspectedofbeingthesourcewhichintroducedthepathogenintothepool.

Acurrentcontroversialhypothesis,underinvestigation,isthatbytryingtoridourlivesofthepresenceofbacteria,weriskreducingourimmunity.Thisisperhapsmerelythescientificcommunityputtingaglossonwhatparentsalreadyknow:ifyousendyouryoungchildtoapreschoolorplaygrouptheywillcomehomewithallmannerofcoldsandillnesseswhichsomehowhelpthechildgrowupwithamorerobustconstitution.

Therecentdebate,however,hascentredmoreonhealthproblemswhichseemtorelatetoaffluenceandcleanliving.Publichealthauthoritiesknowthattheratesofasthma,hayfever,childhoodeczemaandotherallergiesaregenerallyincreasingindevelopednationssuchasWesternEurope,Australia,JapanandtheUnitedStates.Accordingtothehypothesis,bycleaningupourimmediateenvironmentsothoroughlywithantibacterialsurfacecleansers,soapsandevenantibacterialpillowschildrengrowupwithoutthestimulinecessarytoputtheirimmatureimmunesystemstothetest.Itisthesetests,itisargued,whichhelpdeterminewhetherinfutureaperson'simmunesystemwillrespondtoanallergenortoxininawaywhichreleaseshistaminesinsidethebody.(Histaminestriggersomeveryfamiliarsideeffects,includingitchyeyes,arunnynoseandwheezybreathing.)

Itisaninterestingproposition.Ifwearenotexposedtoaverywiderangeofbacteriaandothermicroorganismsatanearlyage,doourdefencemechanismsproperlydevelopallroundprotectiontechniques,oronlyalimitedresponsetobodilythreats?Arewecleaningourselves,ourhomesandevenourfoodstothepointofourownharm?Shouldwegetupfrominfrontofthetelevisionandspendmoretimeoutside,playinggames,rollinginthedirt,swimmingatthebeachandsocialisingwithawiderangeofpeople?Perhapsitistruethatthemoreweisolateourselvesfromtheenvironment,themoresicklywemightbecome.

Ofcoursethereismoretothisissuethanasinglesimpleanswer.Wedon'treallywanttogobacktoexperiencingpolio,measlesoralifethreateningboutoffoodpoisoning.Nor

shouldweignoretheroleourgenesplayindeterminingourhealthandaffinityforcertainillnesses.Hopefully,furtherresearchwilltellushowtodevelopourimmunesystemstotheirfullestpotential.

ThosewithReducedImmunity

VibriovulnificusandtheparasiteCryptosporidium,generallyfairlyharmlesstoahealthyperson,couldcauseseriousillness,perhapsevendeath,inapersonwithlowimmunity.Peoplewithlowimmunityinclude:children,pregnantwomen,nursingmothers,theaged,transplantrecipients,thoseusingimmunosuppressantdrugstotreatcancerorevenasthma,peoplewithHIV.

Itisrecommendedthatpeoplewithlowimmunityboilalldrinkingandcookingwater(onastoveorinakettlewithoutanautomaticcutoff).OneofthemainreasonsistokillCryptosporidiumparvum,whichisparticularlydangerousforthosewithreducedimmunity.Normallytheillnessassociatedwiththisprotozoanrunsitscourseofdiarrhoea,weightlossandabdominalpainwithintwoorthreeweeks.However,ifapersonhasreducedimmunityitcanlasttwiceaslongorcanevenbecomeachronichealthproblem,withinfectionofthebody'sorgansandtissues.Atpresentthereisnoknowneffectivemedicaltreatmenttocombatthisillness.

Cryptosporidiumisfoundinthewatersuppliesofmanytowns,citiesandcountries,particularlyindevelopingnationsbutalso,onoccasion,inindustrialisedcitiesandtowns.ItwasinvolvedintheSydneywaterscareofJulySeptember1998.(ItisimportanttonotethatthereareanumberofdifferentstrainsofCryptosporidium,butnotallstrainscauseillness.Somearepathogenic:othersarenot.)

BecauseitissocommoninplaceslikeAfricaandAsia,itisbelievedtobeamajorcauseoftravellers'diarrhoea.Thisprotozoanisresistanttochlorinetreatment(asusedbywaterauthorities)and,thankstoitsminutesize,canevadeallbutthemostsophisticatedfiltrationsystems.Itisariskforeveryonebutamostparticularriskforchildren,theelderly,peoplewithHIV,thoseundergoingcancertherapy,andotherswithlowimmunity.

WhyAreOlderPeopleatGreaterRisk?

Therearesomeideasastowhywebecomemorevulnerabletofoodpoisoningaswemoveintooldage.Forexample,anolderpersonsecreteslessacidintheirstomachwheneating,andstomachacidisoneofthetoolsourbodyusestocombatbacteriainfoodanddrink.Generalimmunitycangointoagradualdeclinetoo.

Sometimesoursensesdeteriorateasweage,particularlyourresponsetosmellandtaste.Whilethismightmeanwebecomemoreatriskofeatinganddrinkingspoiledfood(likesourmilk)thisshouldnotbeconfusedwithanyabilitytospotfoodwhichmightleadtopoisoningorinfection.

Olderpeoplecanalsobeatincreasedriskoffoodborneillnessforawholerangeofsocialandeconomicreasons,includingincreasedreliance(forthehomebound)onfoodpreparedelsewhereandbroughtover,orfromtryingtosavemoneybyhangingontoleftoversorfoodpastitsusebydate.

PregnantWomen

Listeria,inparticular,isadangerousformoffoodpoisoningforanyonewhoispregnant:theunbornchildcanbeaffected,andmiscarriagecanoccur.Listeriosiscanevenbefataltotheadult.Sometimestheauthoritiesissuespecificwarnings:theBritishDepartmentofHealthadvisespregnantwomennottoeatpatewhilepregnant.Formosthealthy,nonpregnantadults,however,Listeriaisnotmuchofaproblem.

VirusessuchashepatitisAandhepatitisE,whichcanbefoodborne,maycauseamoresevereillnessinpregnantwomen,resultinginahighmortalityrate.Figuresforwomenindevelopingnationsshowdeathratesofabout17percentforhepatitisAandashighas33percentforhepatitisE.Indevelopednationsthedeathrateswouldnotbethisgrim,butthewarningremainspertinent.

Summary

Theelderlyandpregnantwomenshouldbewaryoffoodslikesoftcheeses,pateandcoleslaw.

BeparticularycarefulwithfoodslikechickenforchildrenunderoneyearofagebecauseoftheheightenedsusceptibilityofthisagegrouptoSalmonellainfection.

Rawmeatsareaspecialproblemforthoseagedonetofouryears.

Thosewithlowimmunityshouldboiltheirdrinkingwater.

Chapter4HowDoIProtectMyself,MyFamilyandFriends?

Genrallyspeaking,peoplewhoarestressed,overtired,recoveringfromillness,aswellastheveryyoungandtheelderly,aremoresusceptibletofoodpoisoningandfoodborneillnessthanarehealthypeople.

Maintainingyourgoodgeneralhealthisyourfirstlineofdefence.Thisinvolves:

havingaproperdiet

drinkingplentyofcleanwater

gettingadequaterestandrecreation

gettingregularexercise

breathingcleanair

havingapositiveattitudeonlife.

HowYourBodyProtectsItself

Ourtechniquesandtricksformakingfoodsafetoeatareonlypartoftheequation.Indeed,themostspectaculardefencesoccurnaturally,withinourbodies.

Thebody'sfirstlineofdefenceistheacidinourstomachs.Stomachacid,whichistypicallyaroundapHof3,killsmanyharmfulbacteriabeforetheyreachtheintestinewheretheyfindmorefavourableconditionsforgrowth.Ontheotherhand,fatinfattyfoodslikechocolatecanhelpprotectbacteriafromstomachacids,therebylettingthemmaketheirwaytotheintestinewheretheygrow.Theuseofantacidmedicines,orsimplyhavingalottodrinkwithyourmeal,candilutestomachacidsandleadtothesameresult.

TIPColdstoragemerelybuysyoutime:notsafety!

Anotherlineofdefenceisthemultitudeofharmlessbacteriawhichnaturallyliveinourdigestivesystem.Thesebacteriacompeteforavailablenutrientsandtherebylimitthegrowthofanypathogenicbacteria,whichthendieofforpassoutofthebodybeforetheygetachancetomultiplyandcauseproblems.Theuseofantibioticscanleadtoareductioninthelevelsofgoodbacteriainourdigestivesystemandtherebymakeusmorevulnerabletofoodpoisoningforafewweeksaftertakingthetreatment.Thisiswhereeatinga'probiotic'food,suchasayoghurtcontaininglivebacteria,mayhelpbuildupthenumbersofgoodbacteriaandincreaseourresistancetofoodpoisoning.Thispracticeisparticularlybeneficialwhenrecoveringfromillness,orbeforegoingoverseas.

Somebacteriamultiplytolargeandharmfulnumbersoncetheyreachourintestine:forexample,Salmonellatyphi(whichproducestyphoidfever)andVibriocholera.Oneofthebody'sdefencestosuchbacteriaistheproductionofwhitecellswhichconsumeanddestroytheinvaders.Whitecellsarealsoanimportantdefenceagainstfoodpoisoningcausedbyviruses.Theimmunesystemalsoproducesantibodieswhichdestroythevirusparticles.

Someofthesymptomstraditionallyassociatedwithfoodpoisoningvomitinganddiarrhoeaaremechanismsusedbythebodytoriditselfoftoxicsubstancesbeforetoomuchpoisonhasbeenabsorbed.Andtheyactquicklytomovelargevolumesout.

Theliverisanothermajorplayerinourdefenceagainsttoxinssuchaspesticideresidues,orchemicalssuchasleadandarsenicwhichmaybeinourfoodanddrink.Oncethesechemicalshavebeenabsorbedbythebodytheygenerallypasstotheliverwheretheyare'detoxified',orconvertedtoaformwhichcanbeexcretedfromthebodyinurineorfaeces.

Insomeinstances,suchaswhere'heavy'metalsareinvolved,thedetoxificationprocesstransportstheelementtoyourhair,whereitcanbestoredoutofharm'swayuntilthehairfallsoutoriscut.Itbecomes,inaway,geographicallyisolated.

FoodStorage,PreparationandPreservation.

Livinginadevelopednationitiseasytogainahighlevelofprotectionagainstfoodpoisoningandfoodintoxication.Ofcourse,youcanneverhavefoolproofprotectionfromfoodborneillness,butyoucangetalongwaybylearningtherules.Herewewillrunthroughwhatworksandwhatdoesn'ttosolvetheproblems.

Cold

Freezingwillnotkillbacteria,butitwillstopthemgrowingandreproducing,holdingtheminakindoflimbo.Howcoldiscoldenough?Youneedtokeepfoodatatemperaturebelow5C(40F)intherefrigeratororbelow18C(0F)ifitistobeputinthefreezerforlongertermstorage.Ofcourse,thismeansyouhavetobecarefulwhenyoutakefoodoutofthefridgeorfreezerasitmightcontainbacteriajustwaitingfortherighttemperatureandconditionstomultiplyrapidly.

Coldfixesnothingandmakesnofoodsaferthanitwaswhenitfirstwentintothefridgeorfreezer.

HeatandCooking

Cookingisperhapsournumberonehomeprotection.Cooking(toasufficientlyhightemperatureandforasufficientperiodof

TIPCookingisyourmostimportantallyinthefightagainstfoodpoisoning.Itisnottheperfectanswerforallsituations,butitdealseffectivelywithmostofthecommonproblems.

time)willeffectivelykillawholehostoforganismsandvirusescontaminatingfood,including:Salmonella,Campylobacterjejuni,Clostridiumperfringens,Clostridiumbotulinum,Cryptosporidiumparvum,Giardialamblia,Listeriamonocytogenes,Staphylococcusaureus,Vibriocholerae,E.coli,hepatitisA,Norwalkvirus,yeastsandmoulds.

Tokillyeastsandbacteriayoumustheatfoodabove60C(140F)for15minutes.Virusescanrequirehighertemperaturesstill:atleast80C(176F).Manymouldswillgiveupifheatedabove60C(140F)for10minutes.Somebacterialsporesmaysurviveevenhoursofboiling,asinstewsandsoupsforexample.However,ifyoueatthesoupsoonafterheating,thebacteriawillnothavesufficienttimetobecomeaproblem.

'Pasteurisation'isaformofcookingusedextensivelyinthefoodprocessingindustry,particularlyfordairyfoods,cannedfoodsandjuices.Takingmilkasanexample,pasteurisationinvolvesheatingthemilktoahightemperature(butnotboiling)ofatleast72C(162F)for15seconds(oraslightlyhighertemperatureforaslightlylowertime)themilkisthencooledquicklytobelow5C(40F).Milk,evenwhenpasteurised,needstobekeptintherefrigerator,assomebacterialsporesandevensomebacteriacansurvivepasteurisation.UHTmilkis'ultraheattreated'to133C(271F)andthenplacedinasterilepack.Thepackagingisapapercartonorplastictublinedwithpolytheneoraluminiumtokeepoutoxygenandlight.Asaresultofthisprocessandcare,acartonofUHTmilkdoesn'tneedrefrigerationuntilopened.

Butsomeorganismscansurviveattackswhichwouldkillmostothers.Forexample,cookingwillnotalwayskillBacilluscereusandClostridiumperfringensspores.Heatalsohaslittleeffectontoxinsitmightkillthebacteria,butnotthechemicaltoxinsproducedbythosebacteria.NorwillheatdestroytoxinsproducedbyStaphylococcusaureus(thatcontaminatesfoodbycoughsandsneezes).

Drying

Anothermethodofcontrol,withoutnecessarilykillingbacteria,istodrythefood.Byremovingmoisturefromthefooditmakesithardformicroorganismstogrow.Thisistheprocessusedforfoodssuchasdriedsultanas,currants,apricotsandsoon,aswellaspowderedmilkandsundriedtomatoes.Sugar,asusedinjamsandfruitpreserves,alsodriesupanymoisture.'Smoking',wherefoodishungorpacedonarackoverasmoky,woodfire,isanothertraditionaltechniquefordehydratingmeatandfish.

Salting

Saltingisoneoftheveryoldestformsoffoodpreservation.Itisoftenusedincombinationwithdryingthefood,asisthecasewithdehydratedandsaltedmeatslikebeefjerky.Byreducingtheavailablewater,wemakeitdifficultforbacteria,yeastsandmouldstogrow.However,certainlacticacidbacteria,yeastsandmouldscaneithertolerateoradapttomoderatesaltlevelsandstillgrow,causingfoodspoilage.Saltinggenerallydoesnotkillbacteria,sosalted,rawfoodsshouldstillbecookedbeforeeating.

Acid

Acidfoods(measuredasalow'pH'value)alsomakeitdifficultfororganismstogrowandmultiply.ManufacturerswilloftenusevinegarorcitricacidtoturnfoodsfromalkalineorneutralintoamoreacidicpH.

TIPDon'tthinkfoodissaferbecauseitisspicier.

Curriesaresaferfromthelongcookingtime,notthespices.

Spices

Inthemain,spicesdolittletopreservefood,actingprimarilytooverpoweranyunpleasanttastesthatmightdevelopasthefoodgetsolder.However,sometraditionalspices,includingchilli,cinnamon,cloves,garlicandmustardseeds,dohaveamildpreservativeaction.

Alcohol

Alcoholisapreservative.Youmighthaveseenfruit,suchasprunes,keptinajarwithalcohol:itimpartstheflavouroftheliquoraswellaspreservingthefruit.FruitcakesandChristmaspuddingsalsobenefitfromalittlealcohol,althoughthecooking(heat)andhighsugarcontent(fromthedriedfruits)alsoplayapart.

ArtificialPreservatives

Oneofthecommonandbestknownartificialpreservativesissulfurdioxide.Asusedwithfoodsfromprawnstodriedapricotsandwine,itisaveryeffectivepreservative,butpeoplewhosufferfromasthmamaybeunluckyenoughtoexperienceanasthmaattackbroughtonbyeatingfood,oropeningacontainerorpackoffood,preservedusingthiscompound.

Manysalamisusenitratesandnitritesaspreservativesandtogiveapinkcolour(theycanalsobepartofthe'curing'processforhams).Someartificialpreservativeshavelittleornothingtodowithmakingfoodsafe:rather,theyareusedtomaintainadesirableandattractivetaste,textureandappearanceofthefoodsoverthelongperiodfromprocessingtoeventualconsumption.

Manyconsumers,however,wouldrathernothavesomeofthesearguablyunnecessaryadditives.Insomecasespeoplehavefoundtheirhealthorthehealthorbehaviouroftheirchildrenhasimprovedonceartificialadditivesareremovedfromthenormaldiet.

Whenyoueat,doyousometimesfeeldiscomfortandbloatedwithgaswhichsmellslikerotteneggs?GailVines,in'AGutFeeling'inNewScientistforAugust1998,reportedresearch,byJohnCummingsandothersattheDunnNutritionUnit,Addenbrooke'sHospital,Cambridge,lookingataharmfulroleforsulfurdioxide.Thisresearchindicatedthatdietshighinsulfurouscompoundslotsofmeat,takeawayfoods,beer,wine,cider,driedfruitsandmanyotherprocessedfoodscanencouragebadbacteriatoflourishintheintestine,pushingasidetheessentialgoodbacteriaweneedtogenerateprotectivesubstances.Thesuggestionisthatsomegutdiseaseandillness,fromcolitisandCrohn'sdiseasetoirritablebowelsyndromeandpossiblycoloncancer,mightbeencouraged,maintainedoratleastnotpreventedbythesebacteria.Researchcontinuesinthisarea.

UltravioletLight

Ultravioletlightisapurplishlightfromoneendofthelightspectrum:lookforitabovetherowsofhamandslicedmeatsinyourdelicatessen.Itisoflimiteduse,butwillkillsomebacteriaonthesurfaceoffoodshitdirectlybythislight.ItisusedeffectivelyagainstListeriamonocytogenes.

Irradiation.

Radiationkillslivingthings,includingbacteriaandinsectsinfood,andcanstopthemreproducing.Thisisthesimpleideabehindtheprocessofirradiationusingtheradioactiveelementcobalt60.Itcanbeusedondriedfoodssuchasriceandspices,somemeat(hamburgermince),chicken,prawnsandsomefruitandvegetablessuchasstrawberriesandmushrooms.WhilefoodirradiationisnotpermittedinAustraliaatpresent,someimportedfoods,suchascertainprawnsandspices,mayhavebeenirradiated.

VacuumPacking

Vacuumpackingisonewaywemakelifedifficultforthosetypesofbacteriawhichrequireoxygen.Whensomefoodsarecanned,theairissuckedoutofthecontainerjustbeforethelidissealed.Inthecanningindustry,heattreatmentusuallyfollows,andthesealed,airlesscanisheatedtoahightemperature.Foodsarealsosealedinplasticbags,thenvacuumpacked.

Antibiotics

Justasweuseantibioticmedicinestostopthespreadofabacterialinfectioninourbodies,sodofoodmanufacturersintheirfoods.Cheeseandcrumpets,forexample,relyontheantibioticNisin.

GeneticEngineering

Althoughnotnecessarilyanaidinthefightagainstfoodpoisoning,researc

Risky Foods, Safer Choices Avoiding Food Poisoning

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