ChemicalEngineeringandProcessing:ProcessIntensificationVolume47,Issue12,November2008,Pages2256–2261ExtractionofisoflavonoidsfromPuerariabycombiningultrasoundwithmicrowavevacuumYangHua,TaoWanga,MingxiaoWangb,SufangHana,PingyuWana,MaohongFanc,aBeijingUniversityofChemicalTechnology,Beijing100029,ChinabGeneralHospitalofChinaNationalCoalGroupCorp.,Beijing110013,ChinacSchoolofMaterialsScienceandEngineering,GeorgiaInstituteofTechnology,Atlanta,GA30332-0245,USAReceived24December2006.Revised30September2007.Accepted12December2007.Availableonline11January2008.dx.doi.org/10.1016/j.cep.2007.12.013,HowtoCiteorLinkUsingDOIPermissionsReprintsAbstractThisstudyproposesanewmethodtoquicklyextractanddryisoflavonoidsfromPuerariaLobataOhwi(Pueraria)bycombiningultrasoundandmicrowavetechnologies.Thetimerequiredtoextractisoflavonoidsatcomparablelevelsofproductionbyultrasounddisruptionwas20shorterthanbyconventionalrefluxextraction.Moreover,testresultsfordryingtheextractedsubstancefromPuerariashowthatthemicrowave-vacuummethodis10fasterthantheconventionaltwo-...stepvacuumapproach.Finally,differentinstrumentalanalysesofisoflavonoidsobtainedfromPuerariausingtheproposednewmethodshowthatextractionbyultrasounddisruptionandmicrowave-vacuumdryingaffectsneitherthestructurenorthecompositionoftheextractedsubstance.Keywords：Extraction;Isoflavonoids;Microwavedrying;Ultrasound1.IntroductionUltrasoundhasbeenusedtoextractcompoundsfromthevariouspartsofplantsformorethanthreedecades[1].Duetothedisruptionofcellwallsandenhancedmasstransferofcellcontents,ultrasoundisabletoacceleratetheextractionoforganiccompoundsfromthebodiesofplants[2]and[3].Comparedwithconventionalsolventextraction,theuseofultrasoundmakestheextractionofvaluablecompoundsmoreefficientbymeansofshortertimeframesandlowerextractiontemperatures.Ultrasoundiscurrentlyemployedtoextractsuchpharmacologicallyactivecompoundsaspolysaccharides,cellulose,flavonoids,saturatedhydrocarbons,fattyacidesters,andsteroidsfromplantmaterials[4].Microwavedryingisoftenusedtoevaporatewaterinwood,foodstuffs,drugs,andores,amongothercommodities[5]and[6];itcanalsobeusedfordistillation[7]andextraction[8],[9]and[10].Combiningtheapplicationofmicrowaveswithvacuumtechniquesfordryingofferstwomajoradvantages,namely,rapiddryingduetotheabilityofmicrowavestoheatsolventsinstantaneouslyandhomogeneously,andenhancedrateandextentofmasstransferatsub-atmosphericpressureandlowtemperatures,whichisessentialforthermo-labileproducts.Suchdryingtechnologiesarethereforeimportantforindustriessuchaspharmaceuticals[11].ThepresentstudyoftheextractionofisoflavonoidsfromPuerariabyultrasounddisruption,togetherwiththeirdryingbymeansofcombinedmicrowaveandvacuumtechnologies,offersanalternativetoconventionaltechnologiesforextractinganddryingisoflavonoidsfromPueraria.2.Experimental2.1.PlantmaterialsandchemicalsPuerariacollectedinChina'sHenanprovincewaswashed,dried,andcutinto5mmsegments.ThestandardsampleofPuerarinwassuppliedbyChina'sNationalInstitutefortheControlofPharmaceuticalandBiologicalProducts.Analyticalreagent-gradeethanolandethylacetatewereusedinallexperiments.2.2.ExtractionFig.1showsthecombinedmicrowave-ultrasoundexperimentalsetupusedforextraction.Theapparatusconsistsmainlyofanextracti...oncomponent(a),amicrowavedryingcomponent(b)andasolventrecyclingcomponent(c).Ultrasoundextractionwasc...