Adsorption-and-ion-exchange-basic-principles-and-t

pubs.acs.org/JAFCPublishedonWeb12/07/2010©2010AmericanChemicalSociety22J.Agric.FoodChem.2011,59,22–42DOI:10.1021/jf1032203AdsorptionandIonExchange:BasicPrinciplesandTheirApplicationinFoodProcessingJUDITHKAMMERER,REINHOLDCARLE,ANDDIETMARR.KAMMERER*HohenheimUniversity,InstituteofFoodScienceandBiotechnology,ChairPlantFoodstuffTechnology,Garbenstrasse25,D-70599Stuttgart,GermanyAcomprehensiveoverviewofadsorptionandionexchangetechnologyappliedforfoodandnutra-ceuticalproductionpurposesisgiveninthepresentpaper.Emanatingfromthesefieldsofapplica-tion,themainadsorbentandion-exchangeresinmaterials,theirhistoricaldevelopment,industrialproduction,andthemainparameterscharacterizingthesesorbentsarecovered.Furthermore,adsorptionandionexchangeprocessesaredetailed,alsoprovidingprofoundinsightsintokinetics,thermodynamics,andequilibriummodelassumptions.Inaddition,themostimportantindustrialadsorberandionexchangeprocessesmakinguseofvesselsandcolumnsaresummarized.Finally,anextensiveoverviewofselectedindustrialapplicationsofthesetechnologiesisprovided,whichisdividedintogeneralapplications,foodproductionapplications,andtherecoveryofvaluablebio-andtechnofunctionalcompoundsfromthebyproductsofplantfoodprocessing,whichmaybeusedasnaturalfoodadditivesorfortheirpotentialhealth-beneficialeffectsinfunctionalorenrichedfoodsandnutraceuticals.KEYWORDS:Kinetics;equilibriumisotherms;industrialapplication;polyphenols;byproducts;proteins;tocopherols1.INTRODUCTIONTheaimofthepresentreviewistoprovideacomprehensiveandsystematicoverviewoftheapplicationofadsorbentandionexchangetechnologyinthefoodindustry.Thiscomprisesnotonlythecharacterizationofthemainadsorbentandionexchangematerialspermittedforfoodapplication,theirpreparation,andadescriptionofthehistoricaldevelopmentofthistechnologybutalsoadetailedtreatiseofthedifferentkinetics,thermodynamics,andequilibriummodels,whicharecommonlyusedtodescribeadsorptionandionexchangephenomenaindifferentsystems.Inaddition,themajorapplicationsofadsorptionandionexchangetechnologydescribedintheliteraturearereported,andthisde-scriptionhasbeenrestrictedtosolid-liquidsystems.Thissectionissubdividedinto“generalapplications”,givinganinsightintothepotentialuseofthistechnology,“foodproductionapplica-tions”,and“recoveryofvaluablebio-andtechnofunctionalcompoundsfromthebyproductsoffoodprocessing”.Theclear-cutdifferentiationbetweenthelattertwoareasofapplicationwasmadebecauseoftherisingaccumulationofbyproductsduetoanincreasedproductionquantityofindustrialfoods,whichisasso-ciatedwithincreasingcostsforthedisposalofsuchwastestreams.Ontheotherhand,plant-processingbyproductsareofincreasinginterestbecauseoftheirhighcontentsofsecondaryplantmetab-olites,whichhavebeenintenselydiscussedinthepastdecadesduetotheirhealth-promotingproperties.Thisinterestisassociatedwithagrowingmarketofnaturalfoodadditivesandnutraceuticals.Additionally,consumerexpectationsincreasinglyforcefoodproducerstoabstainfromtheuseofsyntheticfoodadditivesandtoapplynatural“healthy”foodcomponents,whichcanbededucedfromanincreasingimportanceofthe“functionalfoods”sector.Theprocessesexemplifiedinthepresentpaperaremainlybasedontheapplicationofsyntheticresinsandweretakenfromscientificpublications,patents,andapplicationbrochuresofresinmanufacturers.2.HISTORICALDEVELOPMENTOFADSORPTIONANDIONEXCHANGETECHNOLOGYAdsorptionphenomenawerealreadyexploitedbytheEgyp-tiansandSumerians,whousedcharcoal3750B.C.forreducingcopper,zinc,andtinlevelsduringbronzemanufacturing.Follow-ingthis,theEgyptiansandlaterHippocratesusedcharcoalforfirstmedicalpurposesbeforethefirstapplicationforpotablewatertreatmentwasdescribedbythePhoenicians.Suchapplica-tionswereratherempirical,andamoresystematicapproachwasnotdevelopeduntil1773,whenthefirstquantitativestudiesofadsorptionphenomenawereperformed.Nowadaysindustrialapplicationsofadsorptiontechnologyrevealgreatdiversity,andsuchtechniqueshavebecomecommonpracticeforgaspurifica-tion,forexample,toremoveobnoxioussmellsfromtheairoringasmaskstoprotectmilitarypersonnelfrompoisonousgasandfurthertodecolorizeaqueousororganicliquids,whichisfurtherdetailedbelow.Numerousgas-solidandliquid-solidphaseadsorptionsystemsusingcharcoal,clay,carbonofanimalorigin,zeolite,and,morerecently,alsoactivatedcarbon,syntheticzeolites,andfurthersyntheticresinsbasedonpolystyrene,polyacrylicesters,orphenolicshavebeendescribed,givingrisetoverydiversefieldsofapplication(1-3).*Correspondingauthor[phoneþþ49-(0)711-459-22995;faxþþ49-(0)711-459-24110;[e-mail]].ReviewJ.Agric.FoodChem.,Vol.59,No.1,201123TheapplicationofionexchangephenomenacanalsobetracedbacktotheOldTestament,intheSecondBookofMoses(Ex15,23EU),wherethepreparationofpotablewaterfrombitterbrackishwaterisdescribed.Thiswasprobablyduetotheremovalofbittercationsthroughionexchangebyapieceofwoodcontainingrottedcellulose;processedcelluloseisknowntodaytobeaveryefficientionexchangematerial.Aroundathousandyearslater,Aristotle(384-322B.C.)describedinhisProblematathedecreaseofthesaltconcentrationofseawaterwhenperco-latingthroughsand.Th