1、BRITISH STANDARD BS EN 13708:2002 Foodstuffs Detection of irradiated food containing crystalline sugar by ESR spectroscopy The European Standard EN 13708:2001 has the status of a British Standard ICS 67.050 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN 13708:2002 This B
2、ritish Standard, having been prepared under the direction of the Consumer Products and Services Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 14 January 2002 BSI 14 January 2002 ISBN 0 580 38397 0 National foreword This Brit
3、ish Standard is the official English language version of EN 13708:2001. The UK participation in its preparation was entrusted to Technical Committee AW/-/3, Food analysis Horizontal methods, which has the responsibility to: A list of organizations represented on this committee can be obtained on req
4、uest to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of
5、the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. a
6、id enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document c
7、omprises a front cover, an inside front cover, the EN title page, pages 2 to 9 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN1
8、3708 October2001 ICS67.050 Englishversion FoodstuffsDetectionofirradiatedfoodcontainingcrystalline sugarbyESRspectroscopy ProduitsalimentairesDtectionparspectroscopiede RsonanceParamagntiqueElectroniquedaliments ionisscontenantdessucrescristalliss LebensmittelESRspektroskopischerNachweisvon bestrahl
9、tenLebensmitteln,diekristallinenZuckerenthalten ThisEuropeanStandardwasapprovedbyCENon20August2001. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographica
10、lreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManag
11、ementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION
12、 COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2001CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN13708:2001EEN13708:2001(E) 2 Contents Foreword2 1 Scope 3 2 Principle3 3 Apparatusandequipmen
13、t. 3 4 Procedure .4 5 Evaluation.4 6 Limitations5 7 Validation6 8 Testreport . .7 AnnexA (normative) Figures .8 Bibliography 9 Foreword ThisEuropeanStandardhasbeenpreparedbyTechnicalCommitteeCEN/TC275“ FoodanalysisHorizontalmethods “, thesecretariatofwhichisheldbyDIN . ThisEuropeanStandardshallbegiv
14、enthestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyApril2002,andconflictingnationalstandardsshallbewithdrawnatthelatestby April2002. ThisEuropeanStandardwaselaboratedonthebasisofaprotocoldevelopedfollowingaconcertedaction supportedbytheCommissionofEurope
15、anUnion(XIIC.).ExpertsandlaboratoriesfromE.U.andEFTAcountries, contributedjointlytothedevelopmentofthisprotocol. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland
16、, France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,Sweden, SwitzerlandandtheUnitedKingdom.EN13708:2001(E) 3 1Scope ThisEuropeanStandardspecifiesamethodforthedetectionoffoodscontainingcrystallinesugarswhichhave beentreatedwithionizingradiation,byanalysingtheele
17、ctronspinresonance(ESR)spectrum,alsocalledelectron paramagneticresonance(EPR)spectrum,ofthefood,see1to7. Interlaboratorystudieshavebeensuccessfullycarriedoutondriedfigs,driedmangoes,driedpapayasand raisins1to3. 2Principle ESRspectroscopydetectsparamagneticcentres(e.g.radicals).Theyareeitherduetoirra
18、diationortoother compoundspresent.Anintenseexternalmagneticfieldproducesadifferencebetweentheenergylevelsofthe electronspinsm s =+and m s =,leadingtoresonanceabsorptionofanappliedmicrowavebeaminthe spectrometer.ESRspectraareconventionallydisplayedasthefirstderivativeoftheabsorptionwithrespecttothe a
19、ppliedmagneticfield. Themagneticfieldandmicrowavefrequencyvaluesdependontheexperimentalarrangements(samplesizeand sampleholder),whiletheirratio(i.e.gvalue)isanintrinsiccharacteristicoftheparamagneticcentreanditslocal coordination.Forfurtherinformation,see1to7. Radiationtreatmentproducesradicalswhich
20、canbedetectedinsolidanddrypartsofthefood.Theintensityofthe signalobtainedincreaseswiththeconcentrationoftheparamagneticcompoundsandthuswiththeapplieddose. 3 Apparatusandequipment Usuallaboratoryapparatusand,inparticular,thefollowing: 3.1CommerciallyavailableXBandESRspectrometer includingmagnet,micro
21、wavebridge,consolewith fieldcontrollerandsignalchannel,rectangularorcylindricalcavity 3.2Gvalue measurement unit includingfrequencycounter,magneticfieldprobe(nuclearmagnetic resonance(NMR)Gaussmeter),oranyotherbuiltingvaluemeasurementunit. 3.3 ESRtubes, ofinternaldiameterabout4,0mm(e.g.Suprasil1)qua
22、rtztubes) 3.4Balance, accuratetothenearest1mg(optional) 3.5 Laboratoryvacuumoven,orfreezedryer 3.6Scalpel 4Procedure 4.1Samplepreparation Preparesuitablepieces(50mgto100mg)ofthefruit,e.g.usingascalpel. 1)Suprasil isanexampleofasuitableproductavailablecommercially.Thisinformationisonlygivenforthe con
23、venienceofusersofthisInternationalStandardanddoesnotconstituteanendorsementbyCENofthis product.EN13708:2001(E) 4 NOTEVariouspartsofthefruitscancontaindifferentquantitiesofcrystallinesugars.Itcanbeadvantageoustotakethete st samplefromtheouterpartsofthefruits. TransferatestportiondirectlyintotheESRtub
24、e(3.3)andstartthemeasurement. Difficultiesintuningthespectrometercavitycanbeexperiencedifthesampleisinsufficientlydry.Inthiscaseeither reducethesamplequantityordryitfurther.Samplesshouldbedriedinalaboratoryvacuumovenatapproximately 40Cunderreducedpressureorinafreezedryer. WARNING:Excessiveheatingcan
25、reducethesignal. 4.2ESRSpectroscopy 4.2.1Spectrometer settings UseatimeconstantandsweeprateappropriateforESRsignalswithlinewidthsof0,2mTto0,4mT.Forexample, thefollowingESRspectrometersettingshavebeenfoundtobesatisfactory: Microwaveradiation: 9,78GHz 2) ,power5mW Magneticfield: 348mTcentrefield 2 ) ,
26、sweepwidth10,0mTto20,0mT; Signalchannel: 50kHzor100kHzmodulationfrequency, 0,15mTto0,4mTmodulationamplitude; 100msto200mstimeconstant 3) sweeprate5mTmin 1 to10mTmin 1 oraccumulationof3to5spectraatgreatersweeprateandshortertimeconstant; Gain: between10 4 and10 6 ; Temperature: ambienttemperature. 4.2
27、.2 Analysisofsample Analysethesamplepreparedasdescribedin4.1inanESRtube(3.3). 5Evaluation 5.1Identificationofirradiatedsamples 5.1.1General IrradiatedfoodcontainingcrystallinesugarshowtypicalmulticomponentESRspectrareflectingthepresenceof radiationinducedradicalsinthesample.Driedfruitsoftencontainsu
28、garparticlesincrystallineform,andtherefore theappearanceofatypicalmulticomponentESRspectrum(seeannexA)indicatesradiationtreatment.Dueto differentmonoanddisaccharidesandduetothechangesinsaccharidecompositionvariousESRspectrumtypes canoccur. OtherirradiatedsugarcontainingfoodstuffsrevealESRspectrawhic
29、hhavesimilarstructures.Sincetheoverall spectrumstructuredependsontheradicalcompositionandonthecrystallinityofthemonoanddisaccharides presentinthesample,variationsinthespectrumcharacteristicsoccur. 2) Thesevaluesareforthespecifiedmicrowavefrequencyandmagneticfield;ifthefrequencyishigher(lower) themag
30、neticfieldstrengthwillbehigher(lower). 3) Thesevaluesareforthespecifiedsweeprate .EN13708:2001(E) 5 FormonocrystallinesamplestheorientationwithintheESRcavitycaninfluencetherelativeintensitiesoftheESR linesandthusthespectralshape.Howeverinthemajorityofdriedfruitsamplesrandomlyorientedmicrocrystalline
31、 sugarsproduceapowdertypespectrum.Thisproducesbroaderlinesandspectralshapeswhicharelesssensitive toorientation.Typicalcharacteristicsaredescribedin5.1.2and5.1.3,andillustratedinfiguresA.2andA.4.Where similarfeaturesareobservedthesamplecanbeidentifiedasirradiated. 5.1.2 Irradiateddriedmangoesanddried
32、papayas AnESRspectrumshowninfigureA.2andhavingthefollowingcharacteristicsissignificantforirradiateddried mangoesanddriedpapayas: overallspectrumwidth: 7,4mTto7,8mT gvalue(centreofspectrum): 2,00350,0010 5.1.3 Irradiateddriedfigsandraisins AnESRspectrumshowninfigureA.4andhavingthefollowingcharacteris
33、ticsissignificantforirradiateddriedfigs andraisins: overallspectrumwidth: 8,7mTto9,1mT gvalue(centreofspectrum): 2,00350,0010 5.1.4 Unirradiatedsamples Unirradiatedsamplesofdriedmangoes,driedpapayas,driedfigsandraisinsshownoESRspectrumatallora broadsingletasshowninfiguresA.1andA.3withagvalueof2,0040
34、0,0010. 5.2 Gvaluemeasurement ForthecharacterisationoftheESRspectrum,especiallyasregardstheidentificationofirradiatedsamples,itis helpfultomeasurethegvaluesoftheESRsignals. Agvalueofasignal, g signal ,iscalculatedusingequation(1): signal g = B v ESR 448 , 71 (1) where: ESR isthemicrowavefrequency,in
35、gigahertz(GHz); B isthemagneticfluxdensity(magneticfieldsettingofthespectrometer),inmillitesla(mT) (10Gauss=10G=1mT). TheprocedureforcalculatingthegvalueoftheESRspectrumofdriedfruitsistopositionthefieldinthecentreof theESRspectrum(CFinfiguresA.1toA.4)andtomeasurethefrequency v(e.g.frequencycounter)a
36、ndthe fieldB(e.g.gaussmeter)atthispoint. 6Limitations Whilethegeneralformationprocessesofradiationinducedradicalsareknown,identificationofthespecificradicals responsibleforindividualsignalshasnotyetbeenachieved.Nevertheless,theassociationbetweenradiation treatmentandthesignalsillustratedinclause5and
37、figuresA.2andA.4hasbeendemonstratedinanumberof studies1to7. MulticomponentESRspectraprovepriorirradiationbuttheabsenceofthespecificspectrumdoesnotconstitute evidencethatthesampleisunirradiated.DifferentmonoordisaccharidesmaydominateinthesampleproducingEN13708:2001(E) 6 differentESRspectraafterirradi
38、ation.Moreover,ifnosugarcrystalsarepresentinthesample,irradiationwillnot producespecificESRsignals. Detectionofirradiateddriedfigs,driedmangoes,driedpapayasandraisinshasbeenvalidated.Thelowerlimitof detectionmainlydependsonthecrystallinityofthesugarinthesample.Detectionofirradiationtreatmentisnot si
39、gnificantlyinfluencedbystorageofatleastseveralmonths. Theapplicabilityofthismethoddependsonthepresenceofsufficientquantitiesofcrystallinesugarinthesample atallstagesofhandlingbetweenirradiationandtesting.Confirmationofsensitivitytoradiationcanbeachieved, wherenecessary,byirradiatingaportionofthesamp
40、leandretesting.Itisimportantthatdriedfruitshavenotbeen rehydratedpriortotesting. 7Validation ThisEuropeanStandardisbasedontwointerlaboratorytests,onewithdriedpapayasandraisins,1,2,andone withdriedmangoesanddriedfigs3. InaninterlaboratorytestcarriedoutbytheCommunityBureauofReference(BCR)1,2,21laborat
41、ories identifiedcodedsamplesofdriedpapayasandraisinswhichwereeitherunirradiatedorirradiatedtoabout0,5kGy, 1kGy,2kGy,4kGyor7kGy(seeTable1). Table1Interlaboratorydata Product Noofsamples Nooffalsenegatives a Nooffalsepositives b Raisins 126 7 c 1 Driedpapayas 126 2 d 0 a Falsenegativesareirradiatedsam
42、plesidentifiedasunirradiated. b Falsepositivesareunirradiatedsamplesidentifiedasirradiated. c Obtainedfromthe19samplesirradiatedat0,5kGy. d Obtainedfromthe21samplesirradiatedat0,5kGy InanotherinterlaboratorytestcarriedoutbytheGermanFederalInstituteforHealthProtectionandVeterinary Medicine(BgVV)3,17l
43、aboratoriesidentifiedcodedsamplesofdriedmangoesanddriedfigswhichwereeither unirradiatedorirradiatedtoabout1kGy,3kGyor5kGy(seeTable2) Table2Interlaboratorydata Product Noofsamples Nooffalsenegatives a Nooffalsepositives b Driedmangoes 184 0 0 Driedfigs 184 2 0 a Falsenegativesareirradiatedsamplesidentifiedasunirradiated. b Falsepositivesareunirradiatedsamplesidentifiedasirradiated. 8 Testreport Thetestreportshallcontainatleastthefollowing:EN13708:2001(E) 7 a) informationnecessary
