MicroencapsulatedIronFortificationandFlavorDevelopmentinCheddarCheese
H.S.Kwak*,Y.S.Ju,H.J.Ahn,J.AhnandS.Lee11
DepartmentofFoodScienceandTechnology,SejongUniversity,98Kunja-dong,Kwangjin-ku,Seoul,143-747,Korea
1DepartmentofFoodandBiotechnology,HanseoUniversity
360Daegok-ri,Haemi-myun,Seosan-si,
Chungchungman-do,356-706,Korea.
Runninghead:IronfortificationinCheddarcheese
Correspondingauthor:H.S.Kwak,Dept.ofFoodScienceandTechnology,SejongUniversity,98Kunja-dong,Kwangjin-ku,Seoul,143-747,Korea.
E-mail:
Tel:(822)3408-3226
Fax:(822)497-8931
ABSTRACT:ThisstudywasdesignedtoexaminetheeffectofmicroencapsulatedironfortifiedCheddarcheeseandvitCasabioavailablehelperofirononchemicalandsensoryaspects.CoatingmaterialwasPGMS,andferricammoniumsulfateandvitCwereselectedascorematerials.ThehighestefficiencyofmicroencapsulationofironandvitCwere72%and94%,respectively,with5:1:50ratio(w/w/v)ascoatingtocorematerialtodistilledwater.TBAabsorbancewassignificantlylowerincapsulatedtreatmentsthanthoseinuncapsulatedtreatmentsduringripening.Theproductionsofshort-chainfreefattyacidandneutralvolatilecompoundwerenotsignificantlydifferentbetweenmicroencapsulatedanduncapsulatedCheddarcheeseduringripeningperiods.Insensoryaspects,bitterness,astrigencyandsournesswerehigherinCheddarcheesefortifiedwithmicroencapsulatedironanduncapsulatedvitCthanothers.ThepresentstudyindicatedthatfortificationofironaswellasvitCdidnotshowanydefectproblemtoCheddarcheese,andsuggestedthepossibilityofironfortificationofCheddarcheese.
Keywords:Cheddarcheese,MicroencapsulatedIron,PGMS,VitaminC
Abbreviationkey:PGMS=polyglycerolmonostearate.
INTRODUCTION
Today,cheese,amajorproductmadeofmilk,hasgainedwidespreadpopularityinworld,evenit'snutritionalandculinaryspecialtyhasbeenknownalongtimeago(Siggelkow,1981).Also,theconsumptionofcheeseandcheeseproductshasbeengraduallyincreasingoverthepastfewyears.Agreatpercentageofthatincreasehasbeenintheconsumptionofcheeseforsnacksorlunches(Wendorff,1981).
Althoughcheeseisanexcellentsourceofcalciumandprotein,itcontainsverylittleiron(Blanc,1981).
Fortificationofironincheesewouldhelpmeetthisnutritionalneed.Usingdairyfoodsasavehicleforsupplementingironseemstobeanadvantagebecausepeoplewhoconsumedietswithlowirondensityusuallyconsumemoredairyproducts(HekmatandMcMahon,1997).Futhermore,iron-fortifieddairyfoodshavearelativelyhighironbioavailiability(Woestyneetal.,1991).However,beforeanysuchfortificationisundertakenincheese,theeffectsofironfortificationonoxidationofmilkfat,andtheeffectofirononsensorycharacteristicsmustbeascertained.
Ironinfoodisabsorbedbytheintestinalmucosaandespecially,nonhemeiron,themajordietarypool,isgreatlyinfluencedbymealcomposition.ItiswellknownthatvitCisapowerfulenhancerofnonhemeironabsorption(LynchandCook,1980).Itsinfluencemaybepronouncedinmealsofironavailability.VitCfacilitatesironabsorptionbyformingachelatewithferricironatacidpHthatremainssolubleatthealkalinepHoftheduodenum.However,theadditionofvitCinfluencesonthequalityofyogurtduetoitshighacid.Therefore,ironandvitCneedmicroencapsulation.
Microencapsulation,whichshowspotentialascarriersofenzymesinthefoodindustry,couldbeagoodvehiclefortheadditionofirontomilk(JacksonandLee,1991;Bersen'evaetal.,1990).Currentlythereisaconsiderableinterestindevelopingencapsulatedflavorsandenzymes.Amongseveralfactorstobeconsidered,choiceofcoatingmaterialisthemostimportantanddependsonthechemicalandphysicalpropertiesofthecorematerial,theprocessusedtoformmicrocapsules,andtheultimatepropertiesdesiredinmicrocapsules.
Formicroencapsulationalthoughseveralresearchershaveusedcoatingmaterialssuchasmilkfat,agar,andgelatin,etc.responsibleforenzyme,flavorandironmicroencapsulationinfoods(BraunandOlson,1986;MageeandOlson,1981a,b),nostudyhasmeasuredtheefficiencyofironmicroencapsulationusingfattyacidesters,andthestabilityofmicrocapsuleitselfandinsidethebody.Therefore,theobjectiveofthisstudywastoexaminetheeffectofmicroencapsulatedironand/orvitCaddedCheddarcheeseonchemicalandsensoryaspectsduringripening.
MATERIALSANDMETHODS
Materials
Forthemicroencapsulationofironcomplex,polyglycerolmonostearate(PGMS)wasusedasacoatingmaterial.ItwaspurchasedfromIl-ShinEmulsifierCo.,LTD.(Seoul,Korea).Ascorematerials,water-solubleironcomplex,ferricammoniumsulfate(FeNH4(SO4)24H2O)andL-ascorbicacidwerepurchasedfromSigmaChemicalCo.(St.Louis,MO,USA)andShinyoPureChemicalCo.LTD(Osaka,Japan)andwereinfoodgrade.
Preparationofmicrocapsule
Microcapsulesofironweremadebypolyglycerolmonostearate(PGMS),whichwasselectedasamajorcoatingmaterialfromourpreviousstudy(Kwaketal.,2001).Also,ferricammoniumsulfateandL-ascorbicacidwereselected(Kwaketal.,2002).Otherexperimentalfactorswereasfollows:theratioofcoatingmaterialtocorematerialwas5:1,and50mLdistilledwaterwasadditionallyaddedbecausePGMSsolutionwashighlyviscous.Thespraysolutionwasheatedat55Cfor20min,andstirredwith1,200rpmfor1minduringspraying.Anairlesspaintsprayer(W-300,WagnerSprayTech.Co.,Markdorf,Germany)nebulizedacoatingmaterial-ironemulsionat45Cintoacyclindercontaininga0.05%polyethylenesorbitanmonostearate(Tween60)solutionat5C.Thediameterofthenozzleorificewas0.33mm.Thechilledfluidwascentrifugedat2,490xgfor10mintoseparateunwashedmicrocapsulesuspension.Microcapsuleswereformedaslipidsolidifiedinthechilledfluid.Themicroencapsulationofironandascorbicacidweredoneintriplicate.
Treatments
Fivedifferentgroupsinthisexperimentwereasfollowed:1)noadditionascontrol(C),2)20ppmuncapsulatedironadded(I),3)20ppmcapsulatedironadded(MI),4)20ppmcapsulatedironand100ppmuncapsulatedvitCadded(MIUC),and5)20ppmcapsulatedironand100ppmcapsulatedaddedvitC(MIMC).
Efficiencyofmicroencapsulation
Forironmeasurement,thedispersionfluidwasassayedforuntrappedironduringmicroencapsulation.Onemilliliterofthedispersionfluidwastakenanddilutedtentimesandtotalironcontentwasmeasuredat259.94nmwave-lengthbyinductivelycoupledplasmaspectrometer(ICP).Lactam8440Modelspectrometer(Plasmalab,Victoria,Austrailia)wasused.Asamplemeasurementwasrunintriplicate.
TotalvitCwasanalyzedspectrophotometricallyusingDNP(2,4-dinitrophenylhydrazine)testdescribed(KoreaFoodCode,2002).Sampleswerepreparedimmediatelybeforeanalysesandkeptcoldandprotectedagainstdaylightduringanalysis.AvitCstocksolutionwasprepareddailybydissolving10mgofvitCin100mLofdeionizedwater(100g/mL).Itwasdilutedwithdeionizedwatertoobtainthefinalconcentrationof10,20,30,40and50g/mL.TotalvitCwasdeterminedusingthecalibrationgraphbasedonconcentration(g/mL)vsabsorbance,prepareddailyrunningfreshstandardsolutions:
ManufactureofCheddarcheese
CheesemakingprocesswasdescribedbyMetzgeretal.(1994).Aftercheesemanufacturing,cheeseswereweighed,vacuumpackagedinabarrierbagandripenedat5Cfor0,1,3,5and7mo.Thecheesesamplesstoredinrefrigeratorfor12hwere0mo.Thecheesemakingexperimentwastriplicateondifferentdaysusingdifferentbatchesoftreatments.
Chemicalcompositionandcheeseyield
Cheesewasanalyzedformoisture,fat,proteinandashusingthemethodsofAssociationofOfficialAnalyticalChemists(AOAC,1990).Cheeseyieldwasdeterminedaswt.cheesex100/wt.milk.
Thiobarbituricacid(TBA)test
Oxidationproductswereanalyzedspectrophotometricallyusingthethiobarbituricacid(TBA)test(Hegenaueretal.,1979).TheTBAreagentwaspreparedimmediatelybeforeusebymixingequalvolumesoffreshlyprepared0.025MTBA(broughtintobyneutralizedwithNaOH)and2MH3PO4/2Mcitricacid.Reactionswereterminatedbypipetting5.0mLofyogurtsamplecontainingironmicrocapsulesintoaglasscentrifugetubeandmixedthroughlywith2.5mLTBAreagent.Themixturewasheatedimmediatelyinaboilingwaterbathforexactly10min,andthencooledonice.Then10mLcyclohexanoneand1mLof4Mammoniumsulfatewereaddedandcentrifugedat2,490xgfor5minatroomtemperature.Theorange-redcyclohexanonesupernatantwasdecantedanditsabsorbanceat532nmwasmeasuredspectrophotometicallyinan1-cmlightpath.Allmeasurementswererunintriplicate.
Analysisofshort-chainfreefattyacid
Cheesesamples(1g)wereremovedperiodicallyandextractedwithdiethyletherandhexanefor2hrandelutedthrougha10mmi.d.glasscolumncontainingneutralaluminaasdescribedbyKwak,JeonPark(1990).AHewlett-PackardModel5880AGCequippedwithaflameionizationdetectorwasused.ThepreparationofFFAwasachievedusinga15mx0.53mmi.d.Nukolfused-silicacapillarycolumn(SuplecoInc.,Bellefonte,PA,USA).TheGCwasoperatedwithheliumcarriergasat2ml/min,hydrogengas37ml/min,andairat300ml/min.Thecolumnovenwasprogrammedasaninitialholdingfor1minat110Candfirstlevelholdingto180Cat5C/minfor10minandholdingfor20min.Bothtemperaturesforinjectoranddetectorwere250C.AllquantitativeanalysesweredonebyrelatingeachpeakareaofindividualFFAtothepeakareaoftridecanoicacidasaninternalstandard.EachFFAwasidentifiedbytheretentiontimeofstandard.
Analysisofneutralvolatilecompounds
Samplesofcheese(40g)wereremovedperiodicallyandaddedwith10mldistilledwater.TwomlofeachdistillatewasusedtotakeheadspacegassampleasdescribedbyBassetteWard(1975).AHewlett-PackardModel5880AGCequippedwithaflameionizationdetectorwasused.Headspacegassampleswereanalyzedonacapillarycolumn(Supelcowax10,30mX0.32mmI.D.Bellefonte,PA).Thecolumnwasoperatedwithnitrogencarriergasataflowrateof1.2ml/min;hydrogengasflowratewas30.0ml/min;airwas300.0ml/min.Temperatureforbothinjectorportanddetectorwasmaintainedat230C.Thecolumnovenwasprogrammedatthreetemperaturelevels:initialholdingfor5minat35C/minandheatingto140Cat15C/min,holdingfor30min.Theconcentrationsofvolatilecompoundswereestimatedbyanalyzingcheesesamplesthatcontainedtheknownconcentrationsandthoseofcontainingnoaddedstandards.Thedifferencebetweenthetwotreatmentswasusedfortheestimationofconcentrationsofindividualvolatilecompounds.
Sensoryanalysis
Seventrainedsensorypanelistsevaluatedrandomlycodedcheeses.Texturewasevaluatedona9-pointscale(1=poorand9=excellent).TypicalCheddarcheeseflavor,acid,andbitternesswerescoredona9-pointscale(1=lowintensityto9=highintensity).
Statisticalanalysis
Datafromthedeterminationofoptimumconditionsofcheeseslurries,one-wayANOVA(SASInstituteInc.,Cary,NC,1985)wasused.Thesignificanceoftheresultswasanalyzedbytheleastsignificantdifference(LSD)test.Differenceofp0.05wereconsideredtobesignificant.
RESULTSANDDISCUSSION
Microencapsulation
Inthepresentstudy,theyieldofironandvitCmicroencapsulationwere72%and94%,respectively.Inourlaboratory,PGMSwasappearedtobehardtospray,therefore,wefoundtheoptimumratioofPGMStodeionizedwatertoreducetheviscosityofPGMSsolution.Inourpreviousstudy,theratioofPGMStoirontodistilledwaterwas5:1:50(w/w/v),efficiencyofthemicroencapsulationwas75%asthehighestvalue(Kwaketal.,inpress,양경미실험).Inaddition,Kimetal.(김박사실험)reportedtheefficienciesofmicroencapsulationforironwas73%and76%forvitC.
ThesizeofmicroencapsulatedironorvitCwithPGMSwasirregularfromnanotomicrometer,andtheaveragesizewasintherangeof2to5m(picturesnotshown).Microscopicexaminationofmicrocapsulesrevealedsphericalparticles.MicrocapsulescontainingironorvitChadsmoothsurfacesandevenlydistributedpockets.Theshapeofthemicrocapsuleswaslikelyaffectedbyencapsulatedconditions.
MageeandOlson(1981a),andBraunandOlson(1986)foundthatlipidandcoolingfluidtemperaturesaffectedtheshapeofmicrocapsulebycontrollingthecoolingrateoflipidcoatings.Theyobservedthatmicrocapsuleswerecylindricalwhenthelipidcoatingwasrapidlycooledandsphericalwhenthelipidwasslowlycooled.
Chemicalcompositionandcheeseyield
InthecompositionoftheChedarcheeses,nodifferencewasfoundbetweencontrolandiron-fortifiedcheese.Moisturecontentofcheesewas36%.
TBAtestduringripening
Theeffectofironfortificationincheddarcheeseonchemicaloxidation(asmeasuredbytheTBAtest)during7moripeningisshowninFig1.Inuncapsulatedironaddedgroup(I),TBAvalueincreaseddramaticallyfrom0.31(0mo)to0.53(7mo).InComparison,capsulatedironaddedgroups(MI,MIUCandMIMC),nodifferencewasfoundas0.12(0mo)and0.16(7mo).WhencomparedwithcapsulatedironwithuncapsulatedvitC(MIUC)andcapsulatedironwithcapsulatedvitC(MIMC),theTBAvaluewasnotsignificantlydifferentduring7moripeningperiod.
Inthisexperiment,TBAabsorbancewassignificantlylowerincapsulatedgroupsthanthoseinuncapsulatedgroup,regardlessofironandvitC,duringstorage.Thesedataindicatedthatoxidationprocessmaybefasterinyogurtsamplescontaininguncapsulatedironthaninthosecontainingcapsulatediron.
Ourpreviousstudy(Kwaketal.,inpress,양경미)showedtheeffectofironfortificationinmilkonchemicaloxidationduring15dstorage.TheyreportedthatTBAabsorbancewassignificantlylowerincapsulatedgroupthanthatinuncapsulatedgroupat15d.Similarresultwasobservedinanotherstudy(김박사)indicatingoxidationprocessmaybefasterinyogurtsamplescontaininguncapsulatedironthaninthosecontainingcapsulatediron.
JacksonandLee(1991)indicatedthatsamplescontaininguncapsulatediron(ferroussulfateandferricchloride)showed2-3timeshighinfattyacidproduction,comparedwiththosecontainingcapsulatedironcomplexwhenmilkfatwasusedasacoatingmaterial.Thereasonwhyironfortificationcausedseveralmodificationsindairyproductscouldbeexplainedthataddedironmayinteractwithcasein,resultinginiron-caseincomplexesandthepresenceofO2actsasaprooxidant,therefore,lipidoxidationincheddarcheesecanbeaccelerated.
Productionofshort-chainfreefattyacids(FFA)
Itiswellknownthatshort-chainfreefattyacids(FFA,C4throughC10)constitutethebackboneofCheddarflavor(LInandJeon,1987).Thertefore,theproductionofshort-chainFFAprofileswasconsideredtobeanimportantaspectinthisstudy.Theproductionsofshort-chainFFAincontrolandexperimentalcheesesripenedfor7moat7CareshowninTable2.Betweencontrolandtreatments,nodifferencewasfound(p0.05)ateveryperiodpoints.During7moripeningperiod,thetotalreleaseofshort-chainFFAproductionwasnotsignificantlydifferentat0and1moripening,however,thereleaseincreasedfrom3moripeningingroupsC,MI,andMIUC.Totalamountofshort-chainFFAwasintherangeof324.5to428,0ppm.Theseresultsindicatedthatlipolysisprocess,whichcontributesthedevelopmentoftheshort-chainFFA,iniron-fortifiedcheesewasnotdiffererntfromincontrol.
Productionofneutralvolatileflavorcompounds
Theproductionofneutralvolatilecompoundswasobservediniron-fortifiedcheeseinTable2.IngroupscontainingnovitC(C,I,andMI),acelaldehydeproductionincreasedsteadilyupto0.50-0.62ppmat7mo.Incomparison,vitCcontaininggroups,regardlessofmicroencapsulartion(MIUCandMIMC),acetaldehydeproductionwas0.26-0.35at7moripening.
Ethanolprductionwasthehighestamongflavorcompoundsmeasuredandshowedasimilartrendinallgroups.Also,theethanolproductionincreaseddramaticallyafter1moupto7moinallgroups.
Otherneutralflavorcompoundsdetectedwereacetone,2-butanone,and2-heptanone.During7moripening,thesecompoundproductionswerenotsignificantlydifferentinneitherbyripeningperiodsnorwithin5differentgroups.Thisstudyindicatedthatneutralvolatileflavorcompoundsiniron-fortifiedCheddarcheesewerenotdifferentfromthatofthecontrolCheddarcheese.
Sensoryanalysis
ThesensorycharacteristicsinfivetreatmentswereshowninTable3.Forbittertaste,ㅑtwasnotsignificantlydifferentamongtreatmentsduring7moripeningincontrol.However,GroupI.whichwasuncapsulatediron-fortifiedcheese,showedasignificantincreasebittertasteafter1moandthereafter.Also,microencapsulatedironfortifiedCheddarcheese(MI)showedahigherscoreat3moripening,comparedwiththoseofothergroups.
Foracidictaste,vitCaddedgroups(MIUCandMIMC,regardlessofironmicroencapsulation)showedsignificantlyhigherscoresat3mo,andat7moandthereafter,respectively,thanthoseofothers.
Forastringency,uncapsulatediron-fortifiedgroup(I)andmicroencpaulatedironandVitC-fortifiedgroup(MIMC)showedhigherscoresat3moandthereafterthanothervalues.
Formetallictaste,iron-fortifiedgroupswithoutVitC(IandMI),regardlessofmicroencapsulation,showedahigherscore.Especially,uncapsulatediron-fortifiedgroup(I)increaseddramaticallythemetallictaste,evenat1mo.
Themajordifferencebetweencontrolandexperimentalgroupswereobservedincolor.UncapsulatedironandVitCaddedgroups(IandMIUC)showedaprofoundcolorchangetoyellowgreen.GroupIwashighlychangedfrom0moupto7moripening,whilegroupMIUCshowedcolorchangeat5moripeningandthereafter.Interestingly,nodiffererncewasfoundbetweencontrolandmicrocapsulatedironaddedgroupsregardlessofVitC(MIandMIMC)throughallripeningperiods.
Cheddarflavorwasdevelopedwithoutadifferncewithripeningperiodinallgroups,exceptforuncapsulatediron-fortifiedcheese(I)ripenedat5and7moripening.
InUncapsulatediron-fortifiedCheddarcheese,cheddarflavordecreasedwithripeningtime.Texturescoreincreasedwithripeningperiodincontrol,however,thosedecreasedinallexperimentalcheeses.
Foroverallpreference,control(C)andcapsulatediron(MI)and/orvitC(MIUCandMIMC)containingtreatmentsshowedahighconsumerpreferenceinallstorageperiods.Howeverm,thescoresofuncapsulatedironcontaininggroup(I)weredramaticallylowercomparedwiththoseofothertreatmentsinallripeningperiods.Thisresultindicatedthatmicroencapsulationprocesswasveryeffectivetomaskoff-tasteandflavorofironandvitC.
Thesensoryqualityofiron-fortifieddairyfoodshasbeenshowntobeeffectivebythecapsulationofbothironandvitC.Twomajoroff-flavorshavebeenassociatedwithdairyproducts:oxidizedflavorresultedfromcatalysisoflipidoxidationbyiron,andsournesscontributedbyvitC.
Ironisknowntocatalyzelipidoxidationresultinginranciditywithdevelopmentofanunpleasantodorandflavor.TheTBAtesthasbeenextensivelyappliedtofoodinwhichtheabsorbanceofTBAreactionproductscorrelatespositivelywithsensoryevaluation.Fortificationwithironcomplexcausesoxidizedoff-flavorandhighTBAnumber.Toavoidoxidizedandmetallicflavorsandcolorchanges,microencapsulationtechniqueswereneeded.(Gaucheron,2000).
CONCLUSION
Thepresentstudydemonstratedthattheratioof5:1:50(w/w/v)ascoating(PGMS)tocorematerial(ironcomplex)todistilledwatershowedahighefficiencyofmicroencapsulationofironandvitCsuchas72%and94%,respectively.OurresultsindicatedthatlipidoxidationprocessmeasuredbyTBAtestwassignificantlyslowerincapsulatedironthaninuncapsulatediron-fortifiedChedarcheese.Insensory,weneedtopointoutthatnosignificantlyadverseeffectswasfoundinmicrocapsulatediron-andvitC-fortifiedCheddarcheeseduring7moripeninginthisexperiment.Therefore,thepresentstudyprovidesanimportantevidencethatmicrocapsulesofironandvitCwereaneffectivemeansoffortification,andcanbeappliedtoCheddarcheesewithoutanychangesinsensoryaspects.
ACKNOWLEDGEMENT
ThisresearchwassupportedbytheSmallMediumBusinessAdministration(SMBA)inSeoul,Korea.
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FigureLegends
Fig1.ChangesofTBAabsorbanceinmicroencapsulatediron-fortified
Cheddarcheesestoredat7Cfor7mo.C,control(no
addition);I,20ppmuncapsulatediron;MI,20ppmcapsulated
iron;MIUC,20ppmcapsulatedironand10ppmuncapsulated
vitC;MIMC,20ppmcapsulatedironand100ppmcapsulated
vitC.