DOC

Sorghum as Dry Land Feedstock for Fuel Ethanol Production

By Maria Sims,2014-02-18 22:15
13 views 0
Sorghum as Dry Land Feedstock for Fuel Ethanol Productionas,AS,Dry,Land,for,Fuel,dry,land,fuel

    Sorghum as Dry Land Feedstock for Fuel

    Ethanol Production

    Dec.2010JournalofNortheastAgriculturalUniversity(EnglishEdition)Vo1.17No.483

    96

    SorghumasDryLandFeedstockforFuelEthanolProduction

    WANGDonghai.andWUXiaorong

    BiologicalandAgriculturalEngineering,KansasStateUniversity,Manhattan,KS66506,USA

    PostdoctoralResearchAssociate,BiologicalandAgriculturalEngineering,KansasStateUniversity,Manhattan,KS66506,USA

    Abstract:Drylandcropssuchassorghums(grainsorghum,sweetsorghumandforagesorghum)havebeenidentifiedas

    promisingfeedstocksforfuelethanolproduction.Themajorissueforusingthesweetsorghumasfeedstockisitsstabilityatroom

    temperature.Atroomtemperature,thesweetsorghumjuicecouldlosefrom40%to50%ofitsfermentablesugarsfrom7to14days.

    Nosignificantsugarcontentandprofilechangeswereobservedinjuicestoredatrefrigeratortemperatureintwoweeks.Ethanol

    fermentationefficienciesoffreshandfrozenjuicewerehigh((93%).Concentratedjuice(?

    25%sugar)hadsignificantlylower

    efficienciesandlargeamountsoffructoseleftinfinishedbeer;however,wineryyeaststrainsandnovelfermentationtechniquesmay

    solvetheseproblems.Theethanolyieldfromsorghumgrainincreasedasstarchcontentincreased.Nolinearrelationshipbetween

    starchcontentandfermentationefficiencywasfound.Keyfactorsaffectingtheethanolfermentationefficiencyofsorghuminclude

    starchesandproteindigestibility,amylose

    lipidcomplexes,tannincontent,andmashviscosity.Lifecycleanalysisshowedapositive netenergyvalue(NEV)=25500Btu/galethano1.Fouriertransforminfrared(FTIR)spectroscopyandXraydiffraction(XRD)were

    usedtodeterminechangesinthestructureandchemicalcompositionofsorghumbiomasses.Dilutesulfuricacidpretreatmentwas

    effectiveinremovingthehemicellulosefrombiomassesandexposingthecelluloseforenzymatichydrolysis.Foragesorghumlignin

    hadalowersyringyl/guaiacylratioanditspretreatedbiomasswaseasiertohydrolyze.Upto72%hexoseyieldand94%pentose

    yieldwereobtainedbyusingamodifiedsteamexplosionwith2%sulfuricacidat140~Cfor30minandenzymatichydrolysiswith

    cellulase.

    Keywords:diluteacidpretreatment,drylandfeedstock,FTIR,fuelethanol,sorghum,XRD CLCnumber:S216.2:S514Documentcode:AArticleID:10068104(201O)O4

    14 0083

    IntrOdUCtiOn

    Astheworld'sfossilfuelproductionfromthecurrent

    majorenergysources(coal,crudeoil,andnaturalgas)

    isapproachingitspeakl_2

    ,

    peoplemoreandmore

    worryabouttheirfutureenergysupplies.Thesolution

    iseithertodevelopnewtypesofenergysourcesor

    producesubstitutefuelsfromalternativerenewable

    feedstocks.Thefuelethanolproductionisoneofthese

    options,whichexperiencedastronggrowthof8.1%,

    whiletheworldtotalenergyconsumptionfelloff1.1%

    during2009Thefuelethanolcanbeproducedfrom

    eithersugarrichfeedstocks(sugarcane,sugarbeetand

    sweetsorghum),starchrichfeedstocks(cerealgrains,

    potatos,cassavas,etc.),orlignocellulosicfeedstocks (agriculturalandforestresidues,municipalwaste, dedicatedenergycrops,etc.).In2009,approximately 95%ofmorethan10billiongallonsoffuelethanolin theUnitedStateswasproducedfromcorn.and(4%

    wasproducedfromgrainsorghum_jJ.TheRenewable FuelStandard(RFS)intheEnergyIndependenceand SecurityActof2007specifiesthatlignocellulosic

    derivedethanolwil1reach16billiongallonsby2020 Received24August2010

    SupportedbyNationalResearchInitiativeoftheUSDACooperativeStateResearch,Educati

    onandExtensionService(20043550414808)

    WANGDonghai(1959

    ),male,Ph.D,professor,engagedintheresearchofbiofuelsandbiomaterials.E

    mail:dwang@kstate.edu

    http://publish.neau.edu.cn

    ?84?JournalofNortheastAgriculturalUniversity(EnglishEdition)Vo1.17No.42010

    whilethecerealgrainderivedethanolwillremainat 15billiongallons.Tokeepupwithsuchachallenging goal,highperformancecropswithexcellentagro

    nomictraitsforfuelethanolproductionareingreat need.Sorghums(grainsorghum,sweetsorghumand foragesorghum)havebeenidentifiedaspromising feedstocksforbioethanolproductionbecauseofits lowfertilizerrequirement,highwaterefficiency,and otherfavorableagronomictraitsf4J.

    Differentfeedstocksrequiredifferentapproaches orprocedurestoconvertthemaincomponentsin thefeedstocksintofuelethano1.Sweetsorghumcan readilyproducefermentabledisaccharide(sucrose)

    andmonosaccharides(glucoseandfructose)inits juice,starchinitsgrain,andlignocellulose(cellulose andhemicellulose)initsstalk,whichcanbeusedin bothcurrentstarch-basedethanolplantsandfuture cellulosicethanolplants.2030dryt?hm(ofbiomass.

    approximately40%45%arefermentablesugarand

    starch.Ifallfermentablesugarinsweetsorghumis convertedtoethanol,potentialethanolyieldcouldbe 600650gal/acre.Theresearchhasbeenconducted oneffectsofagriculturalpractices5j'harvestapproa-

    ches[6.andjuicerecoverytechniquesonjuiceyield.

    Performanceofdifferentyeaststrains[9-10andfer

    mentationteqhniques[11-16]werea1s0evalUated. Ethanolproductionfromsorghumgrainnormally followssimilardrygrindproceduresascorrlethanol production,whichinvolvesthehydrolysisofstarch intofermentablesugar(glucoseandmaltose)through starchhydrolyzingenzymes(thermalstableamylase

    andamyloglucosidaseorrawgranulehydrolyzing

    amylase)andfermentationofglucoseintoethanol byusingyeast(Saccharomycescerevisiae).Ethanol yieldfromsorghumgrainisgenerallyconsidered comparabletothatfromcorn.Thatis,thehigherthe starchcontentinthegrain,thehighertheethanol yielditwillgenerate.However,fewresearcheshave beenconductedonsorghumgrainregardingfactors impactingtheethanolfermentationperformanceof sorghumvarieties.Alaboratorydrygrindprocedure

    hasbeendevelopedtoevaluatetheethanolproduction

E-mail:xuebaoenglish@neau.edu.ca

    performanceofgrainsorghuml7],whichwillbe

    usedtoevaluatetheperformanceofsomenewly developedgrainsorghumlinesandhybridsforethanol production.

    ProductionoffuelethanolfromlignOcellu1Osic biomassusingthebiologicalrouteinvolvespretreat

    ment,enzymatichydrolysis,andfermentationll8_

    Pretreatmentisacriticalstepthatbreaksupthelignin seal,hydrolyzeshemicellulose,andrenderscellulose inthebiomassmoreaccessibletocellulaseshydro

    lysis[.".

    Idealpretreatmentsshouldbecosteffective.

    causenoorlittlecarbohydratedegradationorloss,and formnooraslittleinhibitorysubstancesaspossible[21.

    Despitemanyotherpretreatmenttechniquesavailable, diluteacidpretreatmentisstillconsideredarelatively inexpensiveandeffectivepretreatmentmethodfor severaltypesofbiomasst.

    Theworkdescribedinthispaperincludesthe

    investigationofchemical,physical,andmicrobial characteristicsofsweetsorghumjuiceunderdifferent preprocesses,storageconditionsandperformanceof thejuiceinethanolfermentation;theevaluationof ethanolfermentationperformanceofsomenewgrain sorghumvarieties,whichmaygeneratethehelpful informationforsorghumbreedersandtheethanol industry,andmayleadtoasystemapproachfor breedingsorghumcultivarsforbioethanolconversion andgraindistillersfeed;thestudyofchangesin

    chemicalcompositionandstructuresinbiomasses fromgrainsorghum,foragesorghum,sweetsorghum, photoperiodsensitivesorghum,andbrownmidrib (BMR)sorghumafterpretreatmentbyusingfourier transforminfraredspectroscopy(FTIR);andXray

    diffraction(XRD)techniquestoanalyzetherelation- shipsamongcomposition,microstructureandfer

    mentablesugaryield.

    MaterialsandMethods

    Materials

    Sweetsorghumjuice:sweetsorghum(M81E)was handharvestedinthelateOctoberandpressedafter WANGDonghaieta1.SorghumasDryLandFeedstockforFuelEthanolProduction?85?

    headsandleaveswereremoved.Juicesampleswere keptinarefrigerator(4?)andfreezer(-20~C)im.

    mediatelyafterharvest.ThebacterialloadandpH valuesofjuicestoredintherefrigeratorandatroom temperatureweremonitoredfor2weekstoevaluate thestoragestabilityofthejuiceunderdifferenttem

    peratures.Seventysorghumsampleswithvarying chemicalcompositionsandphysicalpropertieswere usedinthisstudy.Fourtypesofforagesorghum(stems andleaves)providedbyTexasA&MUniversitywere evaluated.FS1isaphotoperiodsensitiveBMRforage sorghumr4EvergreenBMR);FS2isaphotoperiod

    sensitive,nonBMRsorghum/sudangrass;FS3isa

    BMRforagesorghumclassifiedasamediumearly

    maturinghybrid;andRSisregularforagesorghum(as thecontro1).

    Methods

    RVAtest:RVAtestswereperformedwithaModel S4ARVAanalyzerusingThermoclineforWindows ver.3.10software(NewportScientific,Warriewood, NSW,Australia)usingStandardProcedurel(holding at50?for1min,heatingto95?at1O??min(,

    holdingat95?for2min.andcoolingto50V).

    DSCanalysis:DSCanalysesofselectedsorghum floursampleswereconductedonaPerkinElmer DiamondDSCbyweighing-9mgofflourinto

    stainlesssteelpansonaPerkinElmerautobalance (ModelAD6;PerkinElmerLifeandAnalytical Sciences,Shelton,CT,USA).Theflourwasthen mixedwithdistilledwatertoformaslurrywitha moisturecontentof75%.Thetemperatureprogram

    for3minandthenrampedupto washoldingat3O?

    180?at1O??min(.

    Bacterialcounts:sweetsorghumjuicewasserial dilutedwithsterilewaterr1:10dilution).Bacterial loadsinjuicesamplesweredeterminedbyusinga3M Petrifilmaerobiccountplatebyfollowingthemanu- facturer'sinstructions(3MCorporateHeadquarters,St. Paul,MN).Attheendofthestorageperiod,bacteria inthejuicestoredatroomtemperaturetendedtobe mostlylacticbacteria,whichwereenumeratedby dilutingthejuiceinMRSbrothandincubatingthe PetrifilmplatesinaGasPackiarwithanEZanaerobe pouch.Plateswithcolonynumbersbetween25and 250werechosenforcolonycounting.

    Ethanolfermentation:theethano1fermentation proceduresforsorghumgrainswerethelaboratory

drygrindproceduresdescribedbyWuetal【引.

    Theethano1concentrationinthefinishedbeerwas determinedbyHPLCafterdistillationasdescribedby Wuet,【钔.Theconversionefficiencywascalculated fromthetheoreticalyieldof56.72gofethanolpro

    ducedfrom100gofdrystarch(assuming1gofstarch couldbehydrolyzedinto1.11gglucose,andeach gramofglucosecouldgenerate0.511gofethano1). Forsweetsorghumjuice,100mLofjuice(fresh, autoclaved,orconcentrated)wereweighedinto 250mLErlenmeyerflasksandsupplementedwith 0.3gofyeastextractperflask.Theinoculationand fermentationproceduresandconditionswerethesame asthelaboratorydrygrindprocess.Thehydrolyzing enzymes,Liquozyme(ahightemperaturenamylase

    producedbyBacilluslicheniformis)andSpirizyme (aglucoamylaseproducedbyAspergillusniger), wereprovidedbyNovozymes(NovozymesNorth America,Inc.,Franklinton,NC).Theyeastusedfor ethanolfermentationwasEthanolRedfromFermentis (LesaffreYeastCorp.,Milwaukee,WI).

    Pretreatmentofbiomass:diluteacidpretreatment wascarriedoutinaParrpressurereactor(ParrInstru- mentCompany,Moline,IL)witha1Lreactionvesse1.

    Thegroundsorghumbiomassesweretreatedwith2% dilutedsulfuricacid(w/v)at10%solidloadand140?

    for30min.Pretreatedbiomasswaswashedfourtimes withthehotdistilledwaterandcentrifugedtoremove dissolvedsugarandsulfuricacid.Thesupernatant wascollectedandanalyzedforsugar(glucoseand

    pentoses)contentafterbeingneutralizedtopH-6with CaCO.

    Enzymatichydrolysis:pretreatedbiomasssamples werehydrolyzedinsodiumacetatebuffer(50mmol?. pH4.8,with0.02%(w/v)sodiumazidetopreventthe microbialgrowth.Thehydrolysiswascarriedoutin http://publish.neau.edu.crl

    ?

    86?JournalofNortheastAgriculturalUniversity(EnglishEdition)VO1.17No.42010

    125mLflaskswith50mLbufferslurryat5%solid loadofpretreatedbiomassesina50.Cwaterbath shakeroperatingat140r'min(for96h.Theenzyme

    loading(Accellerase1000TM,GenencorInc.,Rochester, N.Y.,was1mL?g(ofcellulose.Duringenzymatic

    hydrolysis,thehydrolysisslurriesweresampledand analyzedperiodicallyupto96h.Theconversion efficiencyofcellulosewasexpressedintermsofthe percentageofcelluloseenzymaticallyconvertedto glucose(i.e.,enzymaticconversionofcellulose;ECC), whichwascalculatedasdescribedbyVargaetal. XRDtests:foragesorghumsamplesbeforeand aftertreatmentswereanalyzedbyXRDinaBruker AXSD8difraetometer.Pregeneeoferystallinityina samplecanbedetectedbyabsorptionpeaks,andcry' stallinityindex(CrI)wasusedtocomparethecrystalli

    nityamongsamples.

    FTIRspectroscopy:FTIRmeasurementwasper' formedintheoriginalandtreatedforagesorghums usingaThermoNicoletNexusM670FTIRspectro.

    photometerequippedwithaSmartCollector.Reagent

    KBrandsamplesweredriedfor24hat50~Cand thenpreparedbymixing2mgofsamplewith200mg ofspectroscopicgradeKBr.Theanalysiswascarri

    edoutinthewavenumberrangeof400.4000cm(.

    withdetectorat4cmresolutionand32scansper

    sample.

    SEMimages:imagesofpretreatedsurfacesand untreatedforagesorghumwereexaminedusinga HitachiS-3500Nscanningelectronmicroscope(SEM) (Hitachinaka,lbarakiPref.Japan).Specimenswere mountedonconductiveadhesivetape,sputtercoated with4nlrlof60%goldand40%palladiummixture, andobservedusingthevoltagefrom15to20kV. Methodsforanalysesofcrudeprotein,lipid,andash wereAOAC990.03,920.39and942.05,respectively. Crudefiberwasanalyzedbythefilterbagtechnique byusingANKOMA200(http://www.ankom.corn/ media/documents/CrudeFiber

    1108(

    A200.pdf).

    Chemicalcompositionsofuntreatedandpretreated biomassesweredeterminedbyfollowingNRELlabora- toryanalyticalprocedures[.

    E-mail:xuebaoenglish@neau.edu.crl

    ResultsandDiscussion

    Sweetsorghum

    AveragedrymassyieldforsweetsorghumM81Ein

    .Themassranges RileyCounty(KS)was-24t.hm(

    werefrom20to26t.hm(.Drymassyieldforthesame

    sweetsorghuminDoniphanCounty(KS)rangedfrom

Report this document

For any questions or suggestions please email
cust-service@docsford.com