EFFECT OF SACCHARIDES ON GELATINIZATION AND RETROGRADATION OF MODIFIED POTATO STARCH.docx
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EFFECTOFSACCHARIDESONGELATINIZATIONANDRETROGRADATIONOFMODIFIEDPOTATOSTARCH
ElectronicJournalofPolishAgriculturalUniversities(EJPAU)foundedbyallPolishAgricultureUniversitiespresentsoriginalpapersandreviewarticlesrelevanttoallaspectsofagriculturalsciences.Itistargetforpersonsworkingbothinscienceandindustry,regulatoryagenciesorteachinginagriculturalsector.CoveredbyIFISPublishing(FoodScienceandTechnologyAbstracts),ELSEVIERScience-FoodScienceandTechnologyProgram,CASUSA(ChemicalAbstracts),CABIPublishingUKandALPSP(AssociationofLearnedandProfessionalSocietyPublisher-fullmembership).PresentedintheMasterListofThomsonISI.
2008
Volume11
Issue1
Topic:
FoodScienceandTechnology
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Copyright©WydawnictwoAkademiiRolniczejweWroclawiu,ISSN1505-0297
GałkowskaD.2008.EFFECTOFSACCHARIDESONGELATINIZATIONANDRETROGRADATIONOFMODIFIEDPOTATOSTARCH,EJPAU11
(1),#19.
AvailableOnline:
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EFFECTOFSACCHARIDESONGELATINIZATIONANDRETROGRADATIONOFMODIFIEDPOTATOSTARCH
DorotaGałkowska
DepartmentofAnalysisandEvaluationofFoodQuality,AgriculturalUniveristyofCracow,Poland
ABSTRACT
Thegelatinizationandretrogradationofnativepotatostarchandmodifiedpotatostarches(oxidizedstarch,distarchphosphate,andacetylateddistarchadipate)inthepresenceofsaccharides(glucose,fructose,sucrose,andlactose)werestudiedbydifferentialscanningcalorimetry(DSC)andbyturbidimetricanalysis,respectively.Theobviouseffectsarisingfromthepresenceofsaccharidesinthestarchsystemswereashiftinthetransitiontemperaturesofthegelatinizationendothermtohighertemperaturesandincreaseingelatinizationenthalpy.Theextentoftemperatureshiftandenthalpychangewasdependentonboththekindofstarchpreparationandthekindofsaccharideaddedtothestarch-watersystem.However,thegreatestelevatingeffectofsaccharideonthegelatinizationtemperaturesoftheoxidizedstarchandthedistarchphosphatewasobservedinthecaseoffructose.Theadditionofthesaccharides,exceptforlactose,ledtothereductionintherateofretrogradationoftheoxidizedstarchandthedistarchphosphatestarch.
Keywords:
modifiedstarches,saccharides,calorimetricanalysis,retrogradation.
INTRODUCTION
Theinfluenceofsaccharidesonstarchgelatinizationhasbeenstudiedbymanyinvestigators,anditiswellknownthatgelatinizationcharacteristicsaremarkedlyalteredbytheadditionofsugars.Ingeneral,gelatinizationofstarchofdifferentorigininthepresenceofsaccharidesproceedsinhighertemperaturesandrequiresmoreenergyinput(ΔH)thanwithoutsolutes[2,3,4,5,8,19,27,28,32].However,theoppositeeffectofsaccharidesonthevaluesofenthalpyofstarchgelatinizationcanalsooccur[7,18].Moreover,intheworksofEvansandHaisman[11]andMaaurfetal.[20]theenthalpyofgelatinization(ΔH)hasbeenreportedtobeunaffectedbytheadditionofsaccharides.
Theeffectsofdifferentsugarsonstarchgelatinizationvary:
ingeneral,monosaccharidesdelaygelatinisationlessthandisaccharides,exceptmaltose,whichactslikeamonosaccharide[18,26,28].Anumberofpossibleexplanationsforthiseffecthavebeenproposed.Oneofthemsuggeststhatthereisacompetitionbetweenthesugarsandstarchforavailablewater[9,15].InopinionofBiliaderisetal.[6]adecreaseinmoisturecontentresultsinanincreaseintheglasstransitiontemperatureofthebulkamorphousphaseofstarchresultinginanincreaseinthetemperatureoftheoverallendothermicprocessofgelatinization.Whensolutessuchassaccharideareaddedtotheaqueousphase,lesswaterisavailabletoactasplasticizer,andconsequentlythetemperaturesassociatedwithgelatinizationincrease.Sugarsolutionactsasanantiplasticisingcosolventcomparedwiththeactionofwaterasadiluent,andthusgreaterenergyisrequiredtoovercometheantiplasticisingeffectandmeltthestarchcrystals.Theelevatingeffectofsaccharidesongelatinizationtemperatureshasalsobeenattributedtoinhibitionofswellingofthestarchgranules[4,32].SpiesandHoseney[28]suggestedthatthedelayingelatinizationiscausedbythedecreasedwateractivityofthesugarsolutioncomparedwithwater.Theyexplainedthatwhensugarsareaddedtowater,theabilityofwatertointeractwithothercomponentsinthesystemdecreases,resultinginhigherenergyrequirements.
Starchretrogradationprocessisconditionedbythebotanicalsourceofstarchaswellasbythepresenceofothersubstancesinthestarchpaste[13,16,23].Intheaspectoftheeffectofsaccharidesontheretrogradationofstarchesofdifferentbotanicalsources,severalresearchersreportedinconsistentresults.Someofthemhaverevealedthatsaccharidesenhancedstarchretrogradation[3,17,19,25],whiletheothersreportedthatsugarspreventedstarchretrogradation[1,10,17,19,25].Thereareseveralmechanismsthroughwhichsaccharidesmayaffectstarchretrogradation.Itisconsideredthatthemainfactorsaffectingstarchcrystallizationaretheinteractionsofstarchandsaccharide,aswellastheinteractionsofsaccharideandwater[2,3,10,25].
Becausemostofthestudiesongelatinizationandretrogradationofstarchinthepresenceofsaccharidesareonnativestarches,andthereislackofinformationconcerningthepropertiesofcommercialmodifiedstarch-saccharidesystems,theobjectiveofthisworkwastostudygelatinizationandretrogradationofthemodifiedpotatostarchesinthepresenceofmonosaccharidesanddisaccharides.
MATERIALSANDMETHODS
Thestarchesusedintheexperimentswerenativepotatostarch(SuperiorStandard)andmodifiedpotatostarches,i.e.oxidizedstarch(puddingstarchE1404),distarchphosphate(LubostatE1412),andacetylateddistarchadipate(starchthickenerADE1422),producedbyWPPZS.A.(Luboń,Poland).SucroseandglucoseanhydrouswerepurchasedfromChempur(PiekaryŚląskie,Poland),D-(–)-fructosewaspurchasedfromRiedel-de HaënSigma-Aldrich(Seelze,Germany),andlactosemonohydratewasobtainedfromPOCh S.A.(Gliwice,Poland).
Amylosecontents,asdeterminedbythemethoddescribedbyMorrisonandLaignelet[22],ofthestarchsampleswere30.3,18.1,12.4,14.3%(drybasis)forthenativepotatostarch,theoxidizedstarch,thedistarchphosphate,andtheacetylateddistarchadipaterespectively.
TheDSCmeasurementswerecarriedoutinaPerkin-ElmerDSC 7(Connecticut,USA).Starchsamples(approximately10mgdrybasis)wereweightedintothetarredstainlesssteelpansandsaccharidesolutionswereaddedwithmicrosyringetogiveaprecaltulatedstarch-to-water-to-saccharideratioof1 :
3 :
1.Thecontrolsampleswerepreparedbyaddingwatertothesamplepansinsteadofsaccharidesolution.Aftersealing,thepanswereequilibratedfor1hatroomtemperatureandscannedatarateof10°C·min-1from30to120°C.Anemptypanwasusedasareferencetobalancetheheatcapacityofthesamplepan.Thecalorimeterwascalibratedusingindiummetal.Thecharacteristiconset(To),peakmaximum(Tp)andend(Te)temperatures,aswellasoverallenthalpy(ΔH,expressedasJ·g-1drystarch)associatedwithstarchgelatinization,weredetermined.Theaccuracyofthetemperaturemeasurementwas±0.5°Candtheerrorinthecalculationoftheenthalpywas±0.05J·g-1.
RetrogradationofstarcheswasexaminedbyturbidimetricanalysisofJacobsonetal.[16].Thestarchpastescontainingsaccharideswerepreparedasfollows:
theappropriateamountsofsacharideandwaterwereaddedtothestarchsothattheweightratioofstarch(drybasis)tosaccharidewas1 :
1andthestarchsolidsconcentrationofthestarchdispersionwas2%(w/w).Thecontrolsampleswerepreparedinthesamemanner,exceptthatthesamplesdidnotcontainedsaccharide.Eachsamplewasstirredfor5minat300r.p.m.atambienttemperaturebeforebeingheatedto95°C±1°Cinwaterbathfor1h.Afterheatingthesamplewascooledbyplacingthebeakercontainingthesampleundercontinuousstirringinawaterbathheatedto25°C±1°C.Allsampleswerestoredinarefrigeratorat8°C.Onthedayofsamplepreparationandafter1,3,5,7,14,and21daysat8°CtheturbidancevalueofeachsampleweredeterminedusingtheJascoV-530spectrophotometer(Tokyo,Japan)atwavelengthof640nm.Normalizedturbidancewascalculatedas:
whereS0,Sx,S21areturbidancesofthefreshpaste,pasteafterXdays,andpasteafter21days,respectively.
Inthiswork,eachvalueofturbidancerepresentstheaverageoftriplicatedeterminations.Themaximumstandarddeviationofanymeasurementwas<3.5%oftheaveragevalue.
RESULTS
Differentialscanningcalorimetrywasusedtostudytheeffectofsaccharidesonthegelatinizationofnativeandmodifiedpotatostarches.ThegelatinizationtemperaturechangesasaresultofthiseffectaregiveninTable 1.Starchsamplescontainingsaccharideexhibitedhigheronset(To),peak(Tp),andend(Te)temperaturesandinvolvedgreaterenthalpychanges(ΔH)thanthecorrespondingcontrolsamples(withoutsaccharide).
Amongtheinvestigatedstarchsamples,theacetylateddistarchadipatewascharacterizedbythelowestonset,peak,andendtemperatures.Thehighestgelatinizationtemperatureswererecordedinturnforthedistarchphosphatesample(seeTable 1).Thisphenomenacanbeexplainedasbeingduetopresenceofphosphatecross-linksthatstabilizeandstrengthenstarchgranulesandthusmakethemmoreresistanttoswellingandpasting[29].Theacetylateddistarchadipatealsohadthelowestgelatiniz