5辣椒碱辣椒碱-工艺-提取

JournalofSupercriticalFluids22(2002)87–92Phaseequilibriumforcapsaicin+water+ethanol+supercriticalcarbondioxideCatarinaM.M.Duarte*,MarceloCrew1,TeresaCasimiro,AnaAguiar-Ricardo,ManuelNunesdaPonteDepartamentodeQuı´mica,CentrodeQuı´micaFinaeBiotecnologia,FaculdadedeCieˆnciaseTecnologia,Uni
ersidadeNo
adeLisboa,2829-516Caparica,Lisboa,PortugalReceived21February2001;receivedinrevisedform18July2001;accepted17August2001AbstractThepossibilityofextractingcapsaicinwithsupercriticalcarbondioxidefromahydroalcholicmixturecontainingthealkaloidwasinvestigated.High-pressurephaseequilibriumonthequaternarysystemCO2+ethanol+water+capsaicinwasmeasuredinordertoobtaintheseparationfactorofthenaturalproductfromhydro-alcoholicmodelmixtures.Experimentsonphaseequilibriumbehaviorwereperformedatseveralpressures(12,15and18MPa)andtemperaturesof40and50°C.Theseparationfactorsforthreemixturesofdifferentcomposition—0.40water+0.60ethanolmassfractionand0.9water+0.10ethanolmassfraction,containing0.02%ofcapsaicinand0.40watermassfractioncontaining0.04%ofcapsaicin—arecompared.Theeffectofthewatercontentintheselectivityoftheextractionprocessisdiscussed.©2002ElsevierScienceB.V.Allrightsreserved.Keywords:Capsaicin;Alkaloids;Hydroalcoholicmixtures;Vapor–liquidequilibrium;Supercriticalfluidextractionflu1.IntroductionExtractionwithsupercriticalcarbondioxidehasfoundmanyapplicationsintheprocessingofnaturalproducts[1,2].Mostoftheseapplicationsinvolveextractionfromsolidmaterialsinlargehigh-pressurevessels,inbatchorsemi-batchmode.Fractionationofliquidsincountercurrentextractioncolumnsisamoreadvantageouspro-cess,asitmaybeperformedcontinuouslyandusingmuchsmallervolumesunderpressure.However,inmostcasesthetargetsubstancestoberecoveredfromnaturalproductsaretrappedinsolidmaterial.Fractionationcanonlybeusedasasecondarystep,afteraprimaryextractionwithaliquidsolvent.Supercriticalcarbondioxideisperceivedasanon-toxicsolvent.Ifitistobeusedonlyinasecondstepofaprocess,thefirstextractionshoulduseoneofthefewothersolventsthatarealsoconsideredsuitableforcontactwithproductsforhumanconsumption.Hydroalcoholicmixtures*Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](C.M.M.Du-arte).1OnleavefromtheDepartmentofChemistry,UniversityofNottingham,UK.0896-8446/02/$-seefrontmatter©2002ElsevierScienceB.V.Allrightsreserved.PII:S0896-8446(01)00114-0C.M.M.Duarteetal./J.ofSupercriticalFluids22(2002)87–9288areinthiscategoryandtheyarecurrentlyusedtoextractmanydifferentsubstancesfromplants.Moreover,phaseequilibriumintheternarysys-temwater+ethanol+carbondioxidehasbeenextensivelystudied[3].Inordertoexaminethefeasibilityofthesecondaryextraction,theparti-tioncoefficientofthesubstanceofinterestbe-tweenhigh-pressurecarbondioxideandwater+ethanolmixturesmustbedetermined.Thisworkispartofastudydesignedtoprovidethesedataforaseriesofsubstancesthatarecommonlyextractedfromplants,inparticularalkaloids.Stahlandcollaborators[4]werethefirsttostudythesolubilityofthesesubstancesinsu-percriticalcarbondioxide.Atropine–benzeaceticacid,
-(hydroxylmethyl)-8-methyl-8-azabicyclo[3.2.1]oct-3-ylesterendo(+/−)-andcapsaicin(8-methyl-N-vanillyil-6-nonenamide)areamongthemostsoluble.Atropinewasthesubjectofapreviousreport[5].Capsaicinisthe‘hot’componentofpaprikaandchilipeppersandhasfoundnumerousappli-cations[6].Itcanbeextractedfromthoseplantsusingdifferentsolvents,includingsupercriticalcarbondioxide[7]andwater+ethanolmixtures[8].ZeljkoandSteiner[9]reportedsolubilitiesofcapsaicinindenseCO2atseveralexperimentalconditions.Phaseequilibriumintheternarysystemwa-ter+ethanol+carbondioxidehasbeenexten-sivelystudied[3].However,thedesignofthesupercriticalextractionprocesstocarryoutthesecondstageseparationrequiresadetailedknowl-edgeofthevapor–liquidequilibriumcomposi-tionsofthequaternarymixturesCO2+ethanol+water+naturalproduct.Thebestoptimizedconditionsfortheextrac-tionfromthesolidbotanicalsourcewithahy-droalcoholicsolventwerefoundtobe0.40water+0.60ethanolmassfraction.Afterthepri-maryextraction,thecompositionoftheresultinghydroalcoholicmixturecanbechangedbyevapo-ration.Asthesolutionisevaporateditbecomesmoreviscous.Thecompositionof0.90water+0.10ethanolmassfractioncorrespondstothelimitofacceptableviscosityforthesecondstageextractionwithcarbondioxideinacontinuousmode.High-pressurephaseequilibriumexperimentsonquaternarymixturesCO2+ethanol+water+capsaicinwereperformedatseveralpressures(12,15and18MPa)andatthetemperaturesof40and50°C.Theseparationfactorsforthreemix-turesofdifferentcomposition—0.40water+0.60ethanolmassfractionand0.90water+0.10etha-nolmassfraction,containing0.02%ofcapsaicinand0.40watermassfractioncontaining0.04%ofcapsaicin—arecompared.Theeffectofthewatercontentintheselectivityofthesecondstageex-tractionprocessisdiscussed.2.Experimental2.1.MaterialsThesubstancesusedinthisworkwere:98%purecapsaicinsuppliedbySigma[404-86-4]CAS;99.8%ethanolfromMerck;99.8%methanolfromMerck;99.998mol%carbondioxidefromAirLiquide.Doublydistilledwaterwasalsoused.2.2.Equilibriumdeterminati