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VegetableOilsandFatsforEdibleUseR.O.Feupe

Crudeediblevegetable ilsareub-jectedoariousypesfrocessingforeveraleasons.nesonsumerpreference.Mostpeoplepreferoeatlight-coloredandblandoils.Thepref-erencetemsartlyromheppar-entlyreasonablebutincorrectassump-tionhatnlycolorless,dorless,ndtastelessoilsandfatsarepure.Itistruethatsuchproductscanbeusedwithoutmaskingordetractingromhechar-acteristicflavorandpalatabilityofthefoodsowhichheyhavebeenadded.InheUnitedStatesheonlynotableexceptionsliveoil,whichsprizedprimarilybecauseofitsownodor,la-vor,andcolor.Fromheoilprocessor'sstandpoint,purificationofcrudeoilsisadvantage-ous.omeonsumersouldeer-suadedoccept ewilsavingcharacteristiclavorsnddors,utmarketingawidevarietyofoilsofdif-ferentriginssreatlyacilitatedypurifyingpracticallyallofthemtothepointwhereheiroriginsnotevidenttoheenses.Twoactorsbesidespreferenceandconvenienceareresponsiblefortheex-istencefegetable-oilefineries.numberofoils,ncludingomeofourmostommonndlentifulils,repracticallynediblenhecrudetateandusterocessedoecomeedible.heupplyofnaturallyiquidoilssgreaterhanheupplyofnat-urallysemisolid,orplastic,fats,butthe

demandsustheeverse.Therefore,inorderoupplyhebigdemandorthecarcelasticats,hebundantliquidoilshavetobeconvertedtosemi-solidatsfgood]uality.

Becausefhoseequirements,largendidelyispersedndustrynowonvertsrudeilsromanysourcesntoavarietyofrefinededibleproducts.hendustryayppearcomplex,utctuallytonsistsfnumberfmoreresstandardizedoperations,orunitprocessesrefining,bleaching,hydrogenating,winterizing,anddeodorizing,whicharecombinedandmodifiedomeetpecialondi-tions.earlylldibleegetableilsareirstubjectedoefiningndbleaching.Thenheymaybedeodor-izedandgoirectlyoonsumers,rtheymaybeprocessedurthertoyieldeitherwinterizedoilsorso-calledhard-enedats.egardlessofhekindndnumberofintermediateteps,deodor-izationsnearlylwaysheinaltepinprocessinganyediblefatofvegetableorigin.

PURRFATSROILSompriseamix-tureoffattyacidschemically combinedtoormhathehemistallsri-glycrides.efiningshereforeon-cernedwdththeremovalofundesirablenonglycerideomponents.negeta-bleoils,hempuritiesormallyon-sistofoil-solublesubstances,whichareextractedfromtheseedalongwiththeoil,articlesfeal,ummyub-stances,ndegradationroductsftheoilitself.Theamountsandkindsofthempuritiesependmainlynhetypeandoriginofheeedprocessedandhemethodofextraction.Theun-desirableconstituentsgenerallyamounttoesshan0ercentyweightftherudeilmoreftenonlyto5percent.The oldest and most important

520

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VEGETABLE OILS AND FATS FOR EDIBLE USE 521methodfefiningegetableilsoredibleuseconsistsintreatingthecrudeoilwithaolutionofcausticoda.tlooksikeaimpleprocess,uttn-volvescomplicatedchemicalandphys-icalhenomena.heausticodareactswiththefreefattyacidsthatarepresentinhecrudeoiloormoaps,whichrensolublenheilndthereforeendopassntohewaterphasewherehydrationabsorptionofwater)egins.owever^heconcen-trationoftheremainingcausticsodainthewaterisso high thatthe soapiskeptoutorishrownoutofthewatersolu-tiony henomenonalledaltingout.THEESULTfheiffrenteac-tionsisthetransformationofthewater,thecausticsoda,andthesoapintonu-

merousminute,oft,elatinousar-ticles.imultaneouslyhetheron-fatubstancesphosphatidcs,protein,protein-degradationroducts,ndotherummyubstancesareorcedoutofolutionnheormofcoarseparticlessuspendedintheoil.Someofthecausticodaeactswithaportionofthefatoroiltoformmoresoapandfreelycerin.lmostsoonshevariousypesfparticlesreormedtheyeginolumpogether,ro-alesce.Astheparticlesgrowinsizeandgathernheolorbodiesndthercollodialmpurities,heylsodsorb(occlude)omeoftherefinedoil.Theoilemainingaftercompletionofheoperationsmuchighterncolorandretainsnlyracesfonfatom-pounds.

Insomeoftheolderandsmallerre-fineries,thistreatmentofcrudeoilwithcausticsodaiscarriedoutinlargeopenkettles.Generally,thekettlesarecylin-drical,havecone-shapedbottoms,andhold60,000poundsofoilapiece.Eachkettlehasateamcoilorheatingthechargend tirrerormixing.ilslikeottonseed,oybean,ndeanutarechargedintothe kettleatatemper-atureofabout70F.Afterthebubblesofairhavescapedromheil,hestirrersetorapidmixing,andhe

causticsodaisadded.Amilklikeemul-sionformsmmediately;asthemixingcontinuesmallarticlesfoapp-pearandstarttogrow.Afteramixingperiodof0to45minutes,thesurfaceofthemixtureofoilandcausticolu-tiongraduallyassumesalightlygran-ularextureecausefhelumpingtogetherfoaparticles.hissknownsheinreak.tirringssloweddown,andsteamisturnedintotheheatingcoilsoaiseheempera-turefheilobout40.,twhichointelativelyargelakesfsoftoaporm.Heatingandagitationareiscontinued,ndhemixturesallowedtoseparateintoanupperlayerofclear,efinedoilandaowerayerofcmisolidoaptock,alledoots.Thewoayersreeparatedftercoolingndardeningfheoapstock.Theefinerwhoemployshebatchmethodgenerallyusesenoughcausticsodaoneutralizehereeattyacidsintheoilandprovideanexcessof0.2to0,6percent,basedonheweightofthecrudeoil.Theexactexcessofcaus-ticneededistheamountthatwillpro-ducehedesiredcolornheoilwiththeowestefiningoss.nxcessf0.2 percentisoftensufficientforpeanutoil,utottonseedilftenequires0.5percent ormore.Theconcentrationofcausticodaordinarilyusedore-finings8.0o6.4percent,whichsdeterminedandexpressedonanarbi-trarypecific-gravitycalesegreesBaumeinhisase,2o0Baume.Theowerconcentrationsareusedorhepurerandmoreeasilyre-finedoils.

CONTINUOUSethodsfefiningvegetableilswthausticodaavelargelyeplacedhebatchmethodntheUnitedStates.Continuousefiningw^asirstdvocati^dnuropenhe1890's.Onlynheearly930's,how-ever,didhedevelopmentncontinu-ouscentrifuges,roportioningpumps,andeneralechanicalquipmentreachapointwheretheprocessbecamepracticalandeconomicallyeasible.

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522 1950-1051 YEARBOOK OF AGRICULTUREContinuousperationashed-vantagefliminatingargendn-termittentlyunusedequipmentinfavor

ofmallerndontinuouslyworkingapparatus.lsohemountofmate-rialctuallyeingrocessedtnymomentiselativelymall,ohatheprocessisflexibleandresponsivetothewillfheperator.nheatchmethod,nrrornudgmentmightnecessitatere-refininga batchof60,000poundsfoil,utnheontinuousmethodaimilarerrorcanbedetectedandorrectedeforenppreciableamountfilsamaged.notherimportantadvantage,ofcontinuousop-erationisthattheover-alltimeofcon-tactetweenilndausticodasonly or minutes,andheattackontheoiltselfbyhecausticodaconse-cjuentlyseptominimum.hecentrifugalorceemployedneparat-ingheoaptockndilsremen-douslygreaterhanheorceofgrav-ity,whichctsuringettlingnhekettleprocess.Becausetherateofsepa-ratingheefinedoilandoaptockishigherncentrifuginghannettlingbygravity,heexcesscausticodahaslesstimeinwhichtoattacktherefinedoilndherebyncreaseheefiningloss.Inheontinuousrocess,heilandcausticodasolutionbothat75^to5.)rceliveredoeparatemeasuringdevices,whichusuallycon-sistfositiveisplacement-typepumporheilnd ynchronizedadjustableeteringumporhecausticodaolution.AftertheproperproportionsoftheoilandcausticsodaaremeasuredbytherespectivepumpSjthetwostreamsarecombinedanddis-chargedintoamixingchamber,wehereanmulsionsormed.fteraboutminutenheixinghamber,hewater-oil emulsionisforcedintoatube-typeheatexchanger,wherehotwater,orow-pressureteam,juieklyeatstheemulsiono40.ndausesttobreak,reparate,ntooaptocksuspendedintheoil.Theoilandsoap-stockmixturesowonveyedospecial, high-speed centrifuge,which

separateshemixturendischargestwocontinuousstreams,oneconsistingofefinedilhatontains mallamountofoaptockandw^a ter ,ndtheotherconsistingofamallamountofheemisolidoaptock.Normally,lessthan3minuteselapsefromthetimethecrudeoilentersheproportioningdevicentiltmergessefinedil.Theoilromherefiningcentrifugecanbeettled,iltered,ndtored.tisustomary,ow^ever ,owashtl-mostmmediatelyncerwicewith5to0percentofhotwater180F.),Washingslsoarriedutontinu-ouslyymixingheefinedilwithhotwaterndentrifuginggainose].)aratethesoapyw^ashw^a t e randoil.Thewashedoil,ontainingabout0.5percentofmoisture.Howsoanauto-maticvacuum-drierystem,whichsaverticalcylindricaltankinwhichalow-pressure]o nchesofmercur\^)smaintainedyteam-ejectorumps.Theheated,wetoilissprayedintothistank,wherehewatersvaporated,andheoil,^hichontainsesshan0.1percentofmoisture,semovedatthebottom,Amodificationofthecontinuousre-finingrocessasntroducedbout1942.tsaidoeduceheefininglossofanilonearlyheheoreticalminimum.Thenewprocess,knownsthecontinuousodashprocess,ub-jectsanilowoeparatecfinings.Inheirst, olutionfodash(whichsmuchweakeralkalihancausticsodaand,herefore,cannotat-tackheoil)emovesmostofhereefattyacidswithwhichtcancombinetoormoaps.heecondefining,whichscarriedoutwithcausticodasolution,removesthepigmentsandtheremainderabout .1ercent)fhefreefattyacids.

Whilemostvegetable ilsprocessedinheUnitedStatesoredibleusearerefinedbyoneofthesethreeprocesses,ormodificationsoftht m,everalotherprocessesresed,oo.heimplestofhesesaw^a t e r vashingordegum-ming,whichseferredosefiningbyhydration.Warm,dilutesolutionsof

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VEGETABLE OILS AND FATS FOR EDIBLE USEweakalkaliesorsaltsmaybeused,buta saruleonlywarmwaterisemployed.Warmvatereactswithomeoil-sol-ubleubstances,uchasphosphatidcs,proteins,ndothergummymaterials,toormelativelynsolubleroducts,wliichcanbesejDaratedfromtheoilbycontinuousccntrifuging.Waterwashingbeforealkalirefiningreducesthetotalrefininglossofanoil,buthatadvantageprobablysappre-ciablennly ewnstances.omeoilsalwaysostduringwashing,ndthewashedoilmaybemoredifficulttorefineecausef reaterendencytoormtableemulsionsoremulsionsthatarehardobreak.Crudesoybeanandcornoilsarewashedprimarilyoseparateandrecoverthephosphatides.At>ou.t illionoundsfoybeanphosphatides,alledecithinnhetrade,nd alfmillionoundsfcornphosphatidesareproducedannu-allyintheUnitedStatesbythisprocess.Certaincrudeoilsthat containminoramountsofmpuritiesotherthanreefattyacidscanbeefinedbyaprocessknownsteamefining.tsmerelyaigh-temperatureteamistillationundereducedressure.herudevegetableoilsheatedoabout450F.andmaintainedunderapressureof0.25inchofmercuryorlesswhile steamispassedhrought.heteamtripsthereeattyacidsoutofheoil.The]:>roccssisusedsomewhatinEuropebutnotoftenintheUnitedStates.

Solventefininghasbeendevelopedsorecentlythatonlyaewplantshavebeenbuilttouseit.Bysuchamethod,crudeilsrereateditholventsthathavethepropertyofpreferentiallydissolvingcithertheoilitselfortheim-puritiesintheoil.Eachtypeofsolventfindssennernotherrocessbasedonhepropertyofheolvent.Forexample,reeattyacidsmay(;separatedfromcrudeoilsbyamixtureofwaterandsopropanol,analcohol.Inthismixturethefattyacidsarerela-tivelyolublendheilelativelyinsoluble.Anotherprocessofthistypeemployspropane, impleetroleumydro-

carbon.Aspro]3aneisagasatordinarytemperaturesndtmosphericres-sure,heprocessmustbeoperatedatahighpressure,atwhichh ( ^ .propaneisiquid.tillnotherprocess,whichinvolvesothefiningndractiona-tionoftheoil,employsfurfural.

BLKAGHINGsecessaryoemovethecolorbodies,orpigments,ote-movedromrudeilsuringlkalirefining.igmentsommonomanyvegetableoilsncludehecarotenoids.whichreedndellow,ndhechlorophyllidesandpheophytin,whicharegreen.Inaddition,refinedoilscon-tainegradationroductsfariouscolorsndnknownharacter.omeoilsayontainncommonig-ments ;orexample,gossypol, yellowpigment,soundnlynottonseedoil.

Theamountofanyonepigmentobeemovedyleachingslwayssmall.orxample,bjectionablygreenilsayontainnly.0002percentf hlorophyllidc.efinedcottonseedilsuallyontainsnlyabout.0003ercentfarotcnoid.Crudealmilas elativelyighcontentofthosepigments,owhichitowestseep,range-redolor,uteventscontentofi-carotenesonly0.005to0.20percent.Bleachingisgenerallyaccomplishedbyhectionfbleachingarths,rclays,rariousormsfarbon.Thoseubstancescanadsorbonheirsurfacesheigmentshatrcis-solvedintheoil.Theexactmannerbywhichthisadsorptionisbroughtaboutisnotullyunderstood.However,tsknovv^nhatnheleachingrocc\sstheamountofcolorbodieswhichareremovedromheoildependsonhenatureoftheadsorbentused,itssurfacearea,heoncentrationfheolorbodiesntheoil,andhetemperature.

Almostnyolidaterialhatschemicallynerttowardheoilcanbeusedodsorbheolorbodies,ro-videdhatheolidmaterialsnstateofsubdivisionfineenoughtopro-videhenecessaryurfacearea.How-

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524 19o0-1951 YEARBOOK OF AGRICULTUREever,variouseconomicfactorslimittheselectionfdsorbentsorleachingoilsoeveralypesflaysndoactivatedcarbon.

Theearliestclayusedinthebleach-ingofvegetableoilswasuller'searthywhichoccursnaturallyinextensivede-posits.Themineralissemiplasticwhenwetandrocklikew^hendry.TheactiveadsorbingingredientisacomplexformofydrousluminumiUcatc.smined,hemineralusuallycontains40to60percentoffreemoisture,andtspr(parationa sanadsorbentconsistsinheatingtoemoveoisturendgrindingitoainepowder.Grindingdoesnotproduceheurfaceareae-quiredordsorption,uterelymakesitmoreaccessible.Inecentyc^ars,fuller'searthlargelyhasbeensupplantedbyactivatedclays,w^hichremoreffectivedsorbents.Theclaysarenactivesmined.Highadsorbingpowersmpartedohembytreatmentwith strong mineralacids,afterwhichtheyarerinsedwithwaterandground.ctivatedclaysntendedforremovinghegreenpigmentsfromvegetableilsreeftlightlycidicafterwashingwithwateroemovemostofhetrongmineralacid.Activatedcarbon,orcharcoal,isthethirdtypeof adsorbentcommonlyused.Itisefifectiveinremovingcertaintypesofcompounds,buttsexpensiveanditadsorbslargeamountsofoilthatarenotremovedromhespentcarbon.

Oilsarealmostalwaysbleachedbybatchmethodsinkettleswithcapacitiesof15,000o35,000poundsofoil.Thekettlesmaybepen,rheymaybeconstructedohathebleachingcanbeerformednderacuum.neitherase,heyrequippedithsteamcoilsorheatingthechargeandwithgitatorsorntimatelyixingtheadsorbentandoil.Theiloeleachedsumpedintoheettlendeatedolightlyabove212F.beforetheclayisadded,usuallynmountsangingrom0.5to4.0percent.Justenoughclayisusedtoroduceheesiredegreefbleaching.factivatedcarbonisused,

itsusednconjunctionwithheclayandnmountsof o0percentofthemountoflayused.fteraddi-tionoftheadsorbent,theoil-solidmix-tureisagitatedor5to20minutes.Alongercontactperiodendsodarkenth(^oilndpartlyefeathepurposeoftheoperation.Attheendofthemix-ingeriod,heleachedilndd-sorbentareeparatedbyiltration.ftheleaching'a sonductedndervacuum,heoilscooledbeforeilter-ing.Thelantrocesssontrolledylaboratoryrefiningandbleachingtests,designedode^terminehowmuchandwhattypesofadsorbentsarenecessarytoroduceheesiredolornhebleachedil.hemountfpermis-sibleolorependsnheypendqualityfhendroduct.orn-stance,oilstobemadeintohigh-gradecreamyhorteningsmustbebleachedtoaverylightcolor;ilsntendedorcookingpurposesanbedarker;ndoilsintendedfor useinmayonnaiseandotheraladressingsanerightyellow.Wheneverpossible,oilshavingaminimumcolorbeforebleachingareselectedorrocessingntoight-coloredproducts.Determinationofthecolorofvege-tableoilsismadebymatchingthecolorofheilgainst ombinationfstandardizededndellowlasses.Theedglassesormaeriesofmallincrementsfolorncreasingnn-tensitynaccordancewithatandardcolorcale.heellowlassesormanothereries,but,becauseheeyeslessensitiveoariationsnellow,thedifferencesintheyellowglassesaremanyimesreaterhannheedglasses,ndheilseednlyallwithinelativelywideimits.

AFTERREFININGANDBLEACHING,anoilmayeurtherrocessedynyonefeveralrocedures,ependingontsinalse.Onestseparationintohehighersemisolid)ndower(liquid)eltingractionsyrystal-lization.heobjectofsuchaprocess,called winterization or desteariniza-

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VEGETABLE OILS AND FATS FOR EDIBLE USEtion,soproducealadoilshatwillremainiquidrbright"nouse-holdrefrigeratorsat40o50F.Oilsthatremainliquidatrefrigeratortem-peraturesarepreferredbyhousewivesfortoragenheefrigerator.Manu-facturersfayonnaisendthersaladdressingsusetheseoilstopreventthemulsionromreakingndhesei^arationoftheoilandwateringredi-entsoncooling.Anoilisconsideredtobeadequatelywinterizedftwillemainerfectlyclearheneptt2.or/2hours.Usuallyacommerciallywinter-izedoilwdllemainclearor2hoursoronger.othimeandemperaturemustbepecified,ecauserystalsffatsgrowverylowlyncoldoils.tspossibleoranoiltoredatalowtem-peratureoemainperfectlyclearorseveralweeksutoolidifypartiallyaftertorageoreveralmonths.Cottonseedoilispracticallytheonlyvegetableoilnowwinterizedonalargescale.oybeanandcornoilsntendedforsesaladilsrehilledndfilteredoemoveracesfwax,utthatisnottruewinterization.Soybean,corn,esame,ndunflowerilsrenaturalaladilsndootequirewinterization.ice-branilsela-tivelyasilyinterized,uttsfminorimportancebecauseofitslimitedproduction.Peanutoilcannotbewin-terizedyherdinarymethodsedfcrottonseedilecauseelatinousandonfilterablerystalsreormedwhentischilled.Winterizations batchprocess,nwhich0,000oundsfilmayetreatedatonetime.Theoilispumpedintoong,arrowanksnaefriger-atedroom,orintolarge,well-insulatedmetalankshatcontaincoolingcoils.Initherase,heanksreon-structedohatoartfheilsmorehan ew ^eetrom coolingsurface.Thecoolingsystem,isarrangedsothatasmalltem]D(TaturediTerential(usually0o25.)anbem.ain-tainedconstantlybetweenhecoolingsurfaceandtheoil.Theemperaturefheilsc-

ducedopproximately0.trateofabout0.5.nhour,whichrequires or days.Atabout40.,crystallizationcommencesandeleasesheat,ohatheemperaturefhemassofoilrises2or3F.,eventhoughtheateofheatemovalskeptcon-stant.Afterahorttime,heempera-tureoftheoilstartstogodownagain;whenteachesapointlightlybelowthatatwhichcrystallizationbegan,theoilsilterednilterpressesirecooledtoatemperaturelightlybelow^thatoftPieoil.Theyieldofwinterizedcotton-seedoilusuallyrangesbetween5and75)ercent.Thepresentwinterizationprocessstheeastatisfactoryofheprocessingoperations.tslow.aremustetakenuringhehillingoroducetheighttypeandc^uantityofcrystals.Filtrationsifficult.mproperan-dlingofhechilledoilcausesheoftcrystalsobreakandmakesheepa-rationofheoilandcrystallinemate-rialalmostmpossible.Hardening,rydrognation,heprocesswhichconvertsnaturallyliquidoilsntomorevaluablelasticats,swidelyemployed.Thetechniqueshaveadvancedoheointwhereydro-genatedvegetableoilshavecharacter-isticsuperiortothoseofhogandbeeffats,whichtheyoriginallyweremeanttoimitate.nact,hydrognationnowpermitsprocessorstoturnoutavarietyofplasticatswdthesirablehysicalcharacteristicsthatarespecifiedbeforetheoperationstartstailor-made,sotospeak.heharacteristicsightecontrolledplasticityoverdefiniteem-peratureranges,orcompleteandrapidmeltingat pecifiedemperature,orsuperioremulsifyingproperties.

Besidesardening,woncidentalbenefitsarcobtained :hecolorofthefinalproductisightened,andgreaterresistanceoancidificationandotherdeteriorativerocessesuringtorageanduseisimparted.Chemically,hydrognationisthead-ditionofgaseoushydrogenopartofthearbon-to-carbonoubleondswhichormartfhemoleculef

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526liquidats.headditionofhydrogenatthedoublebondsoccursrapidlyonlyinhepresenceofacatalyst, oreignsubstancehichtselfemainsn-changedduringthereactionandise-movedfromthefatafterthehardeninghasbeencompleted.Nickelandseveralothermetals^withpeciallyreparedsurfaces,rclTectiveatalysts.en-erally,hydrognationscxomplishedbyintimatelymixingthefinelydividedmetalliccatalyst,hydrogen^andoilandheatinghemixtureatatmosphericorhigherpressure.

Thecatalystusedincommercialhy-drognationtoformplasticfatsconsistsofinelydividednickel.Theprepara-tionofthenickelvariessomewhat,andspecialsubstancesmaybeaddedoin-creasetsatalyticctivity.heim-plestformofnickelcatalystismadebysuspendingickelormatennil,generallyavegetableoiloftheypeobehydrogenated,andheatingthemix-tureobout00.thatem-perature,theorganicpartofthenickelsaltdecomposes,withheformationofveryinelydividedmetallicnickel.nanotherethodfreparation,naluminum-nickellloysecomposc^dwithcausticodaolution,whichdis-solvesheluminumnhealloyandleavesthenickelinfinelydividedform.Afterllfhelkalindaltavebeenashedut,heickelsus-pendednilndried.tshenreadyoruse.nothermethods,vari-ousompoundsfickelsuchsnickelhydroxideornickelcarbonate)areprecipitatedondiatomaceousearth,themixturesdriedandground,andtheickelompoundseducedthighemperaturewithgaseoushydro-gen,fterhichheinelyividednickelisaddedtotheoil.Commercialegetable-oilarden-inglantsseremendousuantitiesofpurehydrogen.Manymanufacturetheirownhydrogen.Whereelectricityischeap,hydrogencanbeproducedbyelectrolyzing diluteolutionofcaus-ticoda.Oxygensabyproductoftheprocess,and itis usually collected,com-pressed,andoldnteelcylinders.

1950-191 YEARBOOK OF AGRICULTUREThesteam-ironprocessofmanufac-turinghydrogenistheonemost videly

used.Init,watergasispassedthroughabedofhotronre.hewatergasreducestheoretometalliciron.Steamisassedhroughheeducedron,reoxidizingheronoronoxideandliberatingydrogenhroughimulta-neousreductionofthewatersteam).Thexidation-reductionyclese-peatedoverandover.Otherrocessesorroducingy-drogenncludehewater-gascatalyticprocessndheydrocarbon-reform-ingprocess.nheatterprocess,nat-uralas,rhydrocarbonsromthersources,arecrackcidcatalyticallyinthepresencefteamoroducearbondioxideandhydrogen.Thecarbondi-oxideseparatedromhehydrogenbyhemicalmeans.nhewater-gascatalyticprocess,teamspassedoverhotcokeoproduce mixtureofhy-drogenandcarbonmonoxide.Thecar-bononoxidenheixedassconvertedoarbonioxidendy-drogenynotheratalyzedeactionwithteam.

Allommercialydrognationfvegetableilsnhenitedtatesscarriedoutbythebatchprocessintall,gastight,ylindricalesselsnownsconverters.Theconverters,whichhaveacapacityupo30,000poundsofoil,areequippedwithheatingandcoolingcoils,echanicalgitatorsrthermixingevices,nd eviceordis-tributinghencomingydrogenthroughheoil.Thepreviouslyrefinedandbleachedoilsmixedith mallmountfcatalyst0.05o0.50percentnickel)andpumpedntoheconverter.Thenthereepaceboveheilsvac-uated,gitationstarted,ndteamisntroducedntoheeatingoils.Whenheesiredemperaturesreachedgenerally200o400.),heatingstopped,ndydrogensintroducedandallowedobuildupapressureof0o75poundspersquareinchabovethatoftheatmosphere.Hydrognationsanexothermice-actionthatis,heatisgeneratedinthe

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VEGETABLE OILS AND FATS FOR EDIBLEUSEcatalyst-oilmixturesoonshee-actioncommences.fhehydrogna-tionemperaturesoeepton-stant,heoilscooledsheeactionproceeds.nomenstances,heem-peraturefheilsllowedon-crease;fteachesnnsafeevel,hydrognationsnterruptedempo-rarily.henheesiredegreefhardeninghasbeenattained,helowofhydrogenstopped,hehargescooled,ndheatalystsemovedfromtheoilbyfiltration.Thepointat whichhydrognationisdiscontinuedependsnheypefproductdesired.Forinstance,ifanoilisntendedorusenmargarine,ustenoughhydrogensaddedandcondi-tionsareemployedtomakeafatwhichisemisolidtoomemperaturebutliquidtodyemperature.orheproductionofshortenings,heoilmaybehardenedtoardlikcconsistency,oritmayeardenedompletelyomaterialwhichmeltsat140^F.andis glassliketoomemperature.hecompletelyardenedaterialsblendedwithunhardenedoilsopro-duceo-calledompoundypesfshortenings.Themeltingpointofaiquidatsverysensitivetotheadditionofhydro-gen.Themeltingpointofasimplefatthatontainsnlyrioleinanechangedrom41o61^.yheadditionofonly0.68percentofhydro-gen,whichsheamountrequiredorcompleteaturationofallhecarbon-to-carbonoublebonds. varietyofintermediatemeltingpointscanbeob-tainedbysmalleradditionsofhydrogen.Inheproductionofaemisolid,orplastic,at,hemountfydrogenaddedisthefirstconsideration,butalsoofimportancearetheconditionsunderwhichthehydrognationisconducted.Theemperature,ydrogenressure,typeofcatalyst,concentrationofcata-lyst,ndegreefgitationfhechargellnfluencehemannernwhichhydrogencombineswiththeoil.

Deodorizationsheastprocessingstepnheproductionofediblevege-tableilseforeackaginghemori)(>272251> r j

shipmenttotheconsumer.tsprimarypurposesoemovellndesirableodorsndlavors.everalncidentalbenefitsarehadbydeodorization.Forexample,testroysnyxidationproductspresentintheoil,herebyin-creasingheesistancefheilorancidification.Also,temovesracesofreeattycids,whichrehem-selvesdorlessndasteless,ut,fallowedtoremaininthefinishedprod-uct,wouldowerheemperaturetwhichheilwouldeginomokewhenusedinfrying.Finally,itfurtherreducesheolorfheilhroughdecompositionfomefheig-mentshatemainfterefiningandbleaching.

Odorsnrocessed,utndeodor-ized,atsandoilsncludehoseromtheoriginalrudeil,hoseesultingfrombreakdownofheoiltself,ndthosethatdevelopduringrcnn'mgandbleaching.efiningandbleachingn-duceracesftrong,haracteristicodors,particularlyodorscharacteristicofthebleachingearthused.Thequan-tityfdoriferousomponentsoeremovedromaproperlyprocessedoilissuallyesshan.1ercent.hechemicalatureofheompoundssnotcompletely known,but they includederivativesfheattyacids,swellasaldehydesandhydrocarbons.Ineodorization,heilsreeldundera vacuumandheatedtotemper-atureshatwilldriveoutheodorouscompoundswithoutinjuringtheoilit-self.eanwhile,teamslownthroughheilsocarryonhevola-tilecompounds.

Deodorizationisactuallyanapplica-tionofow-pressureteamdistillation,oftenemployedtoseparatecompoundsofveryowvolatilityromothershav-ingtillowerornovolatility.Thehysicalawsoverninghisformofdistillationmakeitpossibleopredict,mongotherhings,hathetimeequiredodeodorizeabatchofoilataixedemperatureandteam-ingratesdirectlyproportionaloheamountfileingeodorized,i-rectly proportionaltotheabsoluteprs-

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528surethichheperationson-ducted,nverselyroportionalohevolatilityofhepureodoriferousub-stancesjndirectlyroportionalotheogarithmofheatioofnitialofinalconcentrationofthevolatilesub-stancesintheoil.Deodorizationsusuallycarriedoutinlosed,nsulated,erticalteeltankhatolds0,000o0,000poundsofoil.Thelowersectionofthetankisprovidedwithanetworkofcoilsforintroducingsteam.Theupperpartisequippedwithbafflestotrapandre-turnanyoildropletsentrainedbyhevaporeavingheank.Equipmentorroducinghevacuumequiredoreodorizationgenerallyonsistsfultiple-stagesteamejectorsconnectedtoabaromet-ricondenser.uchnpparatusssatisfactoryoremovingheon-densableaporsndimultaneouslykeepinghepressureinhedeodorizerbelow0.12poundpersquareinchabso-lute, whichisacommonandacceptablepressurencommercialdeodorization.

Specialequipmentmustbeprovidedforeatingndmaintaininghee-quiredemperaturefheil.teamisordinarilynotavailableatpressureshighnoughoprovidehenecessarvtemperatures400o00.).nanearlymethodheoilwascontinu-ouslyirculatedetweenheeodor-izernd ystemofubeseatedbydirectheat.nanimprovementonthemethod,mineraloilsheatedandcir-culatedthroughcoilsinthedeodorizer.

1950-1951 YEARBOOK OF AGRICULTUREThemostmodernmethod,owever,utilizesthehotvaporsofahigh-boilingmixturefworganicompounds.Theaporsfhisroduct,whichscalledDowtherm,supplythenecessaryheatyondensingnheoilsfthedeodorizer.Batcheodorizersaveeveralun-desirablefeatures.Theoilinthevesselsiseveraleeteep,husausingpressureradienthroughheilothatnotalloftsdeodorizedthelowressurexistingboveheil.Also,heilmusteeptt ightemperatureoranundesirableengthoftime1o6hours)ocompletethedeodorization.Continuousdeodorizers,whichavoidthedefectsnherentnatcheodor-izers,havebeendeveloped.Acounter-currentlowfilndteamsachievednhem.heontinuousunits,whichoperateatheameem-peraturesndressuressatche-odorizers,akesef ystemfshallowrays.Theoilsdeodorizedasitlowsownwardromneraytothenextwhilethesteamtravelsup-wardhroughhehinayersfil.Thedeodorizedoilscollectedthebottomfheeodorizerandson-tinuouslyemovedhrough uitabletrap.Meanwhile,anequalamountofundeodorizedoilentersheopofhedeodorizer.

R.O.FEUGEis amemberofthetech-nicaltafffheouthernRegionalResearchLaboratory.

TEMPE, stapleoodoftheNewGuineandonesians,smadebyermentingsoybeanswrappedinbananaleaves.Aspecialkindofmold,astrainofRhizopusoryzae,sused.DuringheJapaneseoccupationofNewGuinea,hemoldwaslost.Withoutt,henativeswouldnoteattheoybeansmportedoeedhem.ThemoldwaseturnedoNewGuineabyairmailromSurinam,afteritwaslearnedhatJavaneseaborersherewerecultivatingt.LewisB.Lockwood,NorthernRegionalResearchLaboratory.