ISO 2448-1998 Fruit and vegetable products - Determination of ethanol content《水果和蔬菜制品 乙醇含量的测定》.pdf
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1、A Referencenumbe r ISO2448:1998 (E) INTERNATIONAL STANDARD ISO 2448 Secondedition 19980801 Fruitandvegetableproducts Determinationofethanolcontent ProduitsdrivsdesfruitsetlgumesDterminationdelateneur enthanolISO2448:1998(E) ISO1998 Allrightsreserved.Unlessotherwisespecified,nopartofthispublicationma
2、ybereproducedorutilizedinanyformorbyan ymeans,electronic ormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromthepublisher. InternationalOrganizationforStandardization Casepostale56 CH1211Genve20 Switzerland Internet isoiso.ch PrintedinSwitzerland ii Foreword ISO(theInternati
3、onalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhas therighttoberepresentedon
4、thatcommittee.Internationalorganizations,governmentalandnongovernmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. DraftInternationalStandardsadoptedbythetechnicalcommitteesarecircul
5、atedtothememberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. InternationalStandardISO2448waspreparedbyTechnicalCommiteeISO/TC34,Agriculturalfoodproducts, SubcommitteeSC3, Fruitandvegetableproducts. Thissecondeditioncancelsandreplacest
6、hefirstedition(ISO2448:1973),whichhasbeentechnicallyrevised. AnnexAformsanintegralpartofthisInternationalStandard.INTERNATIONALSTANDARD ISO ISO2448:1998(E) 1 FruitandvegetableproductsDeterminationofethanolcontent 1Scope ThisInternationalStandardspecifiesamethodforthechemicaldeterminationofethanolinf
7、ruitandvegetable products. Themethodisnotapplicabletoproductscontainingmorethan5%( m/m)ofethanol. Inthecaseofproductscontainingessentialoils,itisnecessarytoremovethelatter(seeannexA). 2Definition ForthepurposesofthisInternationalStandard,thefollowingdefinitionapplies. 2.1 ethanolcontent massofthesub
8、stancesdeterminedbythemethodspecifiedinthisInternationalStandard,expressedasa percentagebymassforsolidproductsorasgramsper100mlforliquidproducts 3Principle Separationoftheethanolbydistillation,followedbyoxidationbypotassiumdichromateinasulfuricacidmedium. Determinationoftheexcessdichromatebyammonium
9、iron( II)sulfateinthepresenceofiron( II)1,10 phenanthrolineasindicator. 4Reagents Useonlyreagentsofrecognizedanalyticalgrade,unlessotherwisespecified,anddistilledordemineralizedwateror waterofequivalentpurity. 4.1 Sulfuricacid (H 2 SO 4 ), r 20 =1,84g/ml. 4.2 Dilutesulfuricacid, r 20 =1,49g/ml,conta
10、ining500mlofsulfuricacid(4.1)perlitre. 4.3 Calciumhydroxide Ca(OH) 2 ,suspensionobtainedbyshaking110gto112gofcalciumoxidein1litreof water. 4.4 Potassiumdichromatesolution, containing42,572gofK 2 Cr 2 O 7 perlitre.1mlofthissolutionisequivalentto 0,01gofethanol. 4.5 Potassiumpermanganatesolution, cont
11、aining1,372gofKMnO 4 perlitre.10mlofthissolutionisequivalent to1mlofammoniumiron( II)sulfatesolution(4.6). 4.6 Ammoniumiron( II)sulfatesolution (NH 4 ) 2 Fe(SO 4 ).ISO2448:1998(E) ISO 2 Dissolve170,2gofammoniumiron( II)sulfate hexahydrateinwater.Add20mlofsulfuricacid(4.1)anddiluteto 1litrewithwater.
12、 Stabilizebytheadditionofaluminiumchips.2mlofthissolutionisequivalentto1mlofpotassiumdichromate solution(4.4). 4.7 Iron(II)1,10phenanthrolinesolution . Dissolve0,695gofiron( II)sulfateheptahydrate(FeSO 4 . 7H 2 O)in100mlofwater.Add1,485gof 1,10phenanthrolinemonohydrate(C 12 H 8 N 2 . H 2 O)andheatto
13、aidsolution. Thesolutionkeepswell. 5Apparatus Usuallaboratoryapparatusand,inparticular,thefollowing. 5.1 Distillationapparatus,comprisinga500mlflasksurmountedbyafractionationcolumnandacondenser endinginaslightlytaperedextensionpiecelongenoughtoreachtothebottomofa100mlvolumetricflask. Anyothersteamdi
14、stillationapparatusmaybeused,providedthatitsatisfiesthefollowingcriterion. Nolossofethanolgreaterthan0,02%shalloccurinthecourseofadistillation;i.e.200mlofa10%(V/V) ethanol/watermixturedistilledfivetimesinsuccessionshallcontainatleast9,9 %ofethanolafterthelast distillation. 5.2 Heatingapparatus, whic
15、hdoesnotcauseevenslightdecompositionoftheextractablematerialscontainedin theflask. 5.3 Volumetricflasks, ofcapacity100ml. 5.4 Pipettes,ofcapacities5ml,10mland20ml. 5.5 Burettes, of capacity50ml,fittedwithastopcock. 5.6 Wideneckedflasks, ofcapacity250ml,fittedwithgroundglassstoppers,clean,dry,freefro
16、mgreaseand airtight(absolutetightnesscanbeensuredwiththeaidofapolytetrafluorethylenesleeve). 5.7 Blender. 5.8 Balance, capableofweighingtothenearest0,01g. 6Sampling Itisimportantthelaboratoryreceiveasamplewhichistrulyrepresentativeandhasnotbeendamagedorchanged duringtransportorstorage. Samplingisnot
17、partofthemethodspecifiedinthisInternationalStandard.AsthereisnospecificInternational Standarddealingwithfruitandvegetableproducts,itisrecommendedthatthepartiesconcernedcometoan agreementonthesubject. 7 Preparationoftestsample 7.1 Solidorthickproducts (pure,marmaladeorjam,fruits,vegetables) Blendmech
18、anicallythewholeofthesamplesupplied.Takecarethatthetemperatureoftheproductdoesnotrise. Takeasufficientquantityoftheproducttoenabletwoparalleldeterminationstobecarriedout.ISO ISO2448:1998(E) 3 7.2 Liquidproducts (juices,pulpsandsyrups) Thoroughlymixthesample.Takeasufficientquantityoftheproducttoenabl
19、etwoparalleldeterminationstobe carriedout. 8Procedure NOTE Ifitisrequiredtocheckwhethertherepeatabilityrequirement(clause10)ismet,carryouttwodeterminationsin accordancewith8.2.1to8.2.3. 8.1Test portion Weigh,tothenearest0,01g,amassofthepreparedsample,ortakeavolumeofitsuchthatthequantityofethanol col
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