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ISSN:0974-7435Volume10Issue20BioTechnologyAnIndianJournalFULLPAPERBTAIJ,10(20),2014[12129-12134]EffectsofChitosanonretrogradationpropertiesofwheatstarchLiXing-Ke1,LiuFang-Li2,*,WeiSong-Li1,ZhangHua11DepartmentofFood&BiologicalEngineering,ZhengzhouUniversityofLightIndustry,Zhengzhou4500022Departmentofnursing,HenanUniversity,Kaifeng,475000E-mail:liufangli1229@126.
comABSTRACTStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadinfluenceonthefoodquality.
Chitosanistheonlynaturalcationicpolysaccharidewhichcouldinhibitstarchretrogradation.
TheeffectsofchitosanonretrogradationpropertiesofwheatstarchwerestudiedandthepossibleinfluencemechanismofchitosanonwheatstarchwasinvestigatedbyX-raydiffraction(XRD)andFourierTransformInfraredSpectroscopy(FT-IR)inthepaper.
Resultsshowedthatiodinebluevalueincreasedwhilegelstrengthofwheatstarchdecreasedwithincreasingchitosancontent.
Meanwhilethegelatinizationtemperature,retrogradationenthalpyandretrogradationrateofwheatstarchreducedslightlyfrom62.
71to55.
85℃,4.
68J/gto2.
41J/gand54.
47%to19.
87%respectively.
Distinctivedifferencesbetweenwheatstarchgelswithoutorwithchitosanwereobserved.
Furthermoretheintensityofapeakcloseto16.
9°ofwheatstarchsampleswithchitosanweredecreasedandnarrowedcomparedwiththenativestarch,indicatingthedisappearanceofthetypicalB-pattern,whichimpliedthatchitosancouldretardtherecrystallizationortheretrogradationbehaviorofgelatinizedstarch.
Afterblendedwithchitosan,thestretchingvibrationpeakofhydroxylofwheatstarchshiftedfrom3427.
78to3419.
65,whichindicatedmorehydrogenbondsformedbetweenchitosanandwheatstarch.
KEYWORDSWheatstarch;Chitosan;Retrogradation;Properties;Effects.
12130EffectsofChitosanonretrogradationpropertiesofwheatstarchBTAIJ,10(20)2014INTRODUCTIONStarchisanimportantstructuralcomponentofwheatflour,whichstronglyinfluencesthetextureandshelflifeofthehostproducts.
Stalenessofwheatflourproductsisacomplexphenomenoninvolvingmanyfactorsandprocesses,buttheretrogradationofgelatinizedstarchduringstorageisbelievedtobeanimportantcontributor[1].
Thetermretrogradationreferstothechangesthatoccuringelatinizedstarchuponcooling,whichimpliesfullyreversiblerecrystallizationinthecaseofamylopectinandpartialirreversiblerecrystallizationinthecaseofamylase[2].
Retrogradationresultsinlossofimportantsensoryparametersofmanyfoodproductsmadefromwheatflour,likeflavorandtexture,andleadsmainlytoanincreaseofcrumbfirmnessandlossoffreshness.
Atpresent,manyresearchersareexploringtheuseofpolysaccharidestocontroltheretrogradationrateofstarch-basedproducts.
Thereareanumberofreportsconcerningtheapplicationofnaturalpolysaccharidestomodifytheretrogradationbehaviorofstarch,includingmixturesofteapolysaccharidesandpullulan,flaxseedgumandxanthan,soybean-solublepolysaccharideandgumarabic[1,3-6].
Chitosan[-(1,4)-2-amino-2-deoxy-D-glucopyranose]isacarbohydratederivedbydeacetylationofchitin,whichisthesecondmostabundantbiopolymerinnaturenexttocellulose[7].
Asanatural,nontoxicandbiodegradablebiopolymer,chitosanhasreceivedconsiderableattentioninthefoodindustryduetoitsphysiologicalproperties,nutritionalandbiochemicalactivitiesandhasbeenapprovedasafoodadditiveinmanycountries[8].
Weixin-linreportedthatchitooligosaccharides(averagemolecularweightof1390,degreeofdeacetylationof91%)hadobviousresistancetostarchaging[9].
Wuyueinvestigatedtheeffectofchitooligosaccharidesontheretrogradationofintermediateamylosericestarchandfoundthemolecularsizeofchitosandetermineditsanti-retrogradationcapabilityandchitosanwithmolecularweightbetween5kand10khadthebestanti-retrogradationabilitywhilechitosanwithmolecularweightunder5khadnoeffect[10].
KerchGhadtheoppositeconclusionthatChitosanoligosaccharidesandlowmolecularweightchitosanincreasebreadcrumbstalingrate[11].
Chitosanasfoodadditivewasseldomappliedinthewheatproducts.
Furthermoreapplicationofchitosaninfunctionalfoodsisanareaofparticularinterest.
Theaimofthisstudyistoinvestigatetheeffectofchitosanontheretrogradationpropertiesofwheatstarchandthepossiblemechanisminvolvedchitosanandwheatstarch.
MATERIALSANDMETHODSMaterialsWheatstarchwaspurchasedfromBaodingbrewingco.
,LTD(Shanghai,China).
Solublechitosan(averagemolecularweightof5000,degreeofdeacetylationof95%)waspurchasedfromgoldenshellpharmaceuticalco.
,LTD(Zhejiangprovince,China).
AllotheranalyticallaboratorychemicalsandreagentswerepurchasedfromSinopharmChemicalReagentCompany(Shanghai,China).
IodinebluevalueThebluevalue(BV)wasdeterminedaccordingtothemethodofZengJiewithsomemodifications[12].
Thesample(0.
10g)wasdispersedinboilingwaterfor10minandcooledrapidly.
Starchdispersion(5ml)wastakenina100mLvolumetricflaskalongwith50mLofdeionizedwater,1mol/Laceticacidsolution1mLandiodinereagent1mL(1.
0mgI2/mLand10.
0mgKI/mL).
Thevolumewasmadeupto250mLwithdistilledwaterandmixedimmediately.
Thenstanding30minandcolored.
Controlsolutionsweremadeinthesamewaybutwithoutsample.
Allsampleswerescannedat620nmwithanUV1100spectrophotometer(Mapadainstrument,Shanghai,China).
TheabsorbancevalueofpergramofstarchwasrecordedastheBV.
TexturecharacteristicsChitosanandwheatstarch(0/12、1/48、1/36、1/24、1/12)werepreparedandtransferredtoglassvials,coveredwithaluminumfoil,andheatedinawaterbathat95Cfor20min.
Afterbeingheated,theformedgelswerecooledandstoredat4Cfor24hbeforetest.
Priortothegelstrengthmeasurement,gelsampleswereallowedtoequilibrateattheroomtemperature(25±1C)for30min.
Gelswerepenetratedwithaflat-facedstainlesssteelprobe(10mmdia)attachedtoaModelTAXT2textureanalyzer(StableMicroSystemsLtd.
,Surry,U.
K.
)atacrossheadspeedof0.
3mm/s,Pre-andpost-testspeedwerecontrolledat1.
00mm/s.
Thedistanceofthecompressionwassetat10mm.
Thepenetrationforcewhichwasthepeakforcerequiredtorupturethegelswasexpressedasthegelstrength[8].
Differentialscanningcalorimetry(DSC)ThegelatinizationandretrogradationpropertiesofthesamplesweredeterminedfromtheDSCcurves.
DSCmeasurementswerecarriedoutusingaDSC-Q100apparatus(TAinstrumentCo.
Ltd.
,American).
Theweightratioofdrywheatstarchtowaterwasmaintained1:2andchitosan/wheatstarchmixingratioswere0/12、1/48、1/36、1/24、1/12.
Sampleswereplacedinascrew-topglassbottleanddispersedindistilledwaterbystirringfor2hatroomtemperatureusingamagneticstirrer.
Thecalorimeterwascalibratedwithanindiumstandard.
AllsampleswerepreciselyweighedonanaluminumDSCpan.
Thepanwassealedusingasample-encapsulatingpress.
Theheatingprogramincreasedthesampletemperaturefrom30℃to130℃atarateof5℃/min,followedbycoolingto30℃atthesamerate.
Heatingandcoolingwereperformedinanatmosphereofnitrogengas.
SamplesofthedispersionswereweighedintoanaluminumDSCpan.
Theonsettemperature(To),peaktemperature(Tp),andconclusiontemperature(Tc)weredeterminedfromthefirst-runheatingDSCcurves.
Thegelatinizationenthalpywasevaluatedbasedontheareaofthemainendothermicpeak.
Afterthefirst-runheating,thegelatinizedsampleswerecooledto30℃intheinstrumentandstoredat4℃for4days.
ThestoredsampleswerereheatedBTAIJ,10(20)2014LiuFang-Lietal.
12131toexaminetheeffectsofchitosanonretrogradation.
Theretrogradationratiowascalculatedbydividingthere-gelatinizationenthalpyofthesecondheatingrunbythegelatinizationenthalpyinthefirstheatingrun[1].
MicrostructureThewheatstarchintheabsenceorpresenceofchitosanwerepastedandagedfor7days.
Thenthesampleswerefreeze-driedinafreeze-dryer(Scientz-10N,China)for24hours.
Microstructuresofthefreeze-driedsampleswereobservedusingSEM(Quanta-200,FEI,Netherlands)atanacceleratingvoltageof25KV[13].
X-raydiffractionTherecrystallizationanalysisofthegelatinizedsamplesintheabsenceorpresenceofchitosanwascarriedoutusinganX-raydiffractometer(GeminiE,Agilent,England).
Thesampleswerestoredfor2weeksindesiccatorscontainingP2O5andpulverizedbeforetesting.
Theinstrumentwasoperatedat40kVand30mA.
DiffractogramswereobtainedusingCu-Karadiation,scanningfrom5°2èto35°2èatarateof4°/minandastepsizeof0.
3mm.
OriginPro8.
0SoftwarewasusedtoanalyzethediffractogramsaccordingtothemethodofWuyue[2].
FouriertransforminfraredspectroscopyToperformFT-IRmeasurement,thedriedretrogradedwheatstarcheswithandwithoutchitosan(Theratioofchitosan:wheatstarch1:12)withweightof2mgwerefirstgroundintoflourandthendispersedin200mgKBr(pelletprocedure).
KBrpelletizedstarchsampleswereanalyzedusingaNicolet5700infraredspectrometerintherange4000to400cm1.
TheIRspectraforstarchtreatedwithandwithoutalkaliproteasewererecordedonadiamondplatewith32scansandaresolutionof4cm1[14].
StatisticalanalysisAlldeterminationswererepeatedintriplicate,andthemeanvaluesandSDswerereported.
RESULTSANDDISSICUSIONEffectsofchitosanoniodinebluevalueofwheatstarch0.
000.
020.
040.
060.
080.
104812162024iodinebluevalue(%)chitosanconcentrationFigure1:EffectsofchitosanadditiononIodinebluevalueofwheatstarchFigure1showedthebluevalueofwheatstarchwithdifferentadditionofchitosan.
Withtheadditiondoseofchitosanincreasing,thebluevalueaddedcomparedwiththecontrol.
Theseresultsindicatedthatthecontentoffreestarchincreasedandchitosaninhabitedtheretrogradationofwheatstarch.
Effectsofchitosanongelstrengthofwheatstarchgels0.
000.
020.
040.
060.
080.
10100150200250300gelstrength(Pa)chitosanconcentrationFigure2:Effectsofchitosanadditionongelstrengthofwheatstarchgels12132EffectsofChitosanonretrogradationpropertiesofTofurtherelucidatetheroleofchitosanongelpropertieslevelsofchitosanswereevaluatedbygelstrengthgelsdecreased.
Starchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadinfluenceonthefoodquality.
Gelstrengthgels,whichsuggestedpossiblewheatstarchtexturecharactersandrestrainedtheretrogradationEffectsofchitosanonthermalpropertiesofwheatstarchTABLE1:EffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchsamplesT.
(℃)12/048/136/124/112/157.
96±0.
0446.
39±0.
0941.
75±0.
0340.
89±0.
0239.
85±0.
0362.
71±0.
0560.
76±0.
0260.
40±0.
0457.
16±0.
0355.
85±0.
06DifferentialScanningCalorimetrybehaviourofstarchgelatinizationandretrogradation.
asgelatinizationenthalpyisnecessarytobreakdomeltingenthalpyprovidesaquantitativemeasureoftheenergyusedtoenthalpytogelatinizationenthalpyisconsideredtobeorecrystallization[2].
FromTABLE1,To,TpandTcweresignificantlyretrogradationratioofwheatstarchdecreased.
otherresearchersandcouldbeinterpretedasfollows:interactdirectlywithstarchbyintermolecularhydrogenbondstostaChitosanwasefficienttoretardstarchretrogradationEffectsofchitosanonmicrostructureofwheatstarchgelswheatstarchFigure3:MicrostructureofwheatSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweengelswithoutorwithchitosan(1/12)wereobservedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographofwithchitosanadded(right)showedawellmicrostructuralchangeshelpedtoexplainthesedifferencesbetweenuniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocstructurewithlargepores.
TheseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandchitosanlikeabinderdisperseduniformlyandtightlyassociatedinthegelnetworkEffectsofChitosanonretrogradationpropertiesofwheatstarchTofurtherelucidatetheroleofchitosanongelpropertiesofwheatstarch,gelspreparedwithvariousconcentrationgelstrength.
Withincreasingamountofchitosanadded,gelstrengthStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadofwheatstarchgelsdecreasedproportionallywithmorechitosanwheatstarch-chitosaninteractions.
Therefore,itwaspresumedthatchitosanretrogradationofwheatstarch.
EffectsofchitosanonthermalpropertiesofwheatstarchgelsEffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchTp(℃)Tc(℃)Hg(J/g)retrogradationrati62.
71±0.
0560.
76±0.
0260.
40±0.
0457.
16±0.
0355.
85±0.
0672.
10±0.
0771.
34±0.
0370.
32±0.
0870.
19±0.
0266.
88±0.
054.
68±0.
124.
01±0.
093.
53±0.
233.
31±0.
162.
41±0.
0854.
47±0.
1240.
04±0.
2336.
70±0.
1527.
96±0.
0819.
87±0.
13ScanningCalorimetry(DSC)hasproventobeoneoftheeffectivemethodstodeterminethethermalbehaviourofstarchgelatinizationandretrogradation.
Duringthecourseofgelatinization,acertainquantityofheatexpressedgelatinizationenthalpyisnecessarytobreakdownthecrystallineareasofstarch.
Astoretrogradedstarch,thevalueofprovidesaquantitativemeasureoftheenergyusedtomelttherecrystallizedstarch.
Theenthalpytogelatinizationenthalpyisconsideredtobeoneusefulindicatortodeterminetheweresignificantlydecreasedwithincreasingtheadditiondoseofchitosan.
ofwheatstarchdecreased.
Thedecreaseofgelatinizationtemperatureswereconsistentwiththereportsofandcouldbeinterpretedasfollows:theavailablewaterwasreducedbythehydrationandintermolecularhydrogenbondstostabilizethecrystallineregionsofretardstarchretrogradation.
Effectsofchitosanonmicrostructureofwheatstarchgelschitosan-wheatstarchmixtureMicrostructureofwheatstarchandchitosan-wheatstarchmixtureSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweenwereobserved.
Thestructureofwheatstarchgels(left)showedgranularaggregatedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographof)showedawell-structuredmatrixwithahighlyinterconnectednetworkofstrands.
Thesemicrostructuralchangeshelpedtoexplainthesedifferencesbetweenwheatstarchgelswithoutorwithuniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocstructurewithlargepores.
Theseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandhitosanlikeabinderdisperseduniformlyandtightlyassociatedinthegelnetwork.
BTAIJ,10(20)2014,gelspreparedwithvariousconcentrationadded,gelstrengthofwheatstarchStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadwithmorechitosanincorporatedinchitosancouldenhancetheEffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchduringstorageretrogradationratio(%)54.
47±0.
1240.
04±0.
2336.
70±0.
1527.
96±0.
0819.
87±0.
13theeffectivemethodstodeterminethethermalgelatinization,acertainquantityofheatexpressedretrogradedstarch,thevalueofmelttherecrystallizedstarch.
Theratioofmeltingneusefulindicatortodeterminethedegreeofstarchwithincreasingtheadditiondoseofchitosan.
Andtemperatureswereconsistentwiththereportsoftheavailablewaterwasreducedbythehydrationandchitosancouldcrystallineregionsofwheatstarchgels[5,13].
wheatstarchmixturemixtureSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweenwheatstarch)showedgranularaggregatedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographofwheatstarchgelsetworkofstrands.
Thesegelswithoutorwithchitosan.
Afine,uniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocoarsestructurewithlargepores.
TheseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandwheatstarchandBTAIJ,10(20)2014LiuFang-Lietal.
12133Effectsofchitosanoncrystallinityofwheatstarchgels510152025303550100150200250300Intensity(counts)2-Theta12/012/1Figure4:X-raydiffractionspectraofwheatstarchandchitosan-wheatstarchmixtureInvestigationsusingXRDwereconductedtofurtherandpowerfullyprovethepreventingeffectofchitosanontheretrogradation.
TheXRDpatternsandcorrespondingcrystallinityareshowninFigure4.
OncenativeRSisgelatinized,itdevelopsa"B-type"diffractionpatternduringaging.
Retrogradedstarchgivesa"B-type"diffractionpatternandthisisaccompaniedbygradualincreasesinrigidityandphaseseparationbetweenthepolymerandthesolvent(syneresis).
B-typecrystallinityischaracterizedbyawell-definedpeakat16.
9°(2è).
Theformationofthispeakwastheresultofthecrystallizationoftheamorphousstarchmelt,mainlyoftheamylopectinfractionthatincreasedduringstorage[2].
AsshowninFigure4,theintensityofapeakcloseto16.
9°ofwheatstarchsampleswithchitosanweredecreasedandnarrowedcomparedwiththenativestarch,indicatingthedisappearanceofthetypicalB-pattern,whichimpliedthatchitosancouldretardtherecrystallizationortheretrogradationbehaviorofgelatinizedstarch.
Effectsofchitosanoninfraredspectraofwheatstarchgels0500100015002000250030003500400045000.
550.
600.
650.
700.
750.
80ransmittancewavenumers(cm-1)a:12/0b:12/1Figure5:Fourierinfraredspectraofwheatstarchandchitosan-wheatstarchmixtureFigure5showedtheIRspectraofretrogradedwheatstarcheswithoutandwithchitosan.
Thebandabsorbanceinstarchhavebeenassignedandmatchedwiththevibrationalmodesofthechemicalbondsandthestructuresofstarchmolecules[14].
IRspectraindicatedthattherewasnodifferencebetweenthewheatstarchandchitosan-wheatstarchmixture,whichsuggestedthattherewasnosignificanteffectofchitosanonthestructureofwheatstarch.
ButHydrogenbondspossiblyformedbetweenwheatstarchandchitosanduringretrogradation.
Formationofhydrogenbondsinretrogradedwheatstarchisidentifiedbylow-fieldshiftofwavenumbersforstretchingvibration(3415and3387cm1for–OH).
Afterblendedwithchitosan,thehydroxylstretchingvibrationpeakshiftedfrom3427.
78to3419.
65fromIRspectrawhichsuggestedthatmorehydrogenbondsformedinthesesamples.
CONCLUSIONSFromtheoverallresults,itcouldbeconcludedthattheadditionofchitosantowheatstarchcouldsignificantlyretardretrogradation.
Watermigrationcontributedalottothestarchretrogradation,whichneedsfurtherstudy.
Additionofchitosan12134EffectsofChitosanonretrogradationpropertiesofwheatstarchBTAIJ,10(20)2014towheatproductscreatesanopportunitytocombinebeneficialtechnologicalpropertieswithbeneficialbiologicalhealthpromotingproperties.
Hence,chitosancouldbesuitabletoaddtowheatproductsandsimultaneouslyenhancequalityandnutrition.
Thesestudiesareimportantforthedevelopmentofchitosanasthefoodadditiveinwheatproductstomakethemcompetemoreeffectivelyinthemarkets.
ACKNOWLEDGMENTSThisworkwassupportedbytheprojectofeducationaldepartmentofHenanprovinceandZhengzhouLightIndustryUniversityFundforKeyTeachers.
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ISSN:0974-7435Volume10Issue20BioTechnologyAnIndianJournalFULLPAPERBTAIJ,10(20),2014[12129-12134]EffectsofChitosanonretrogradationpropertiesofwheatstarchLiXing-Ke1,LiuFang-Li2,*,WeiSong-Li1,ZhangHua11DepartmentofFood&BiologicalEngineering,ZhengzhouUniversityofLightIndustry,Zhengzhou4500022Departmentofnursing,HenanUniversity,Kaifeng,475000E-mail:liufangli1229@126.
comABSTRACTStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadinfluenceonthefoodquality.
Chitosanistheonlynaturalcationicpolysaccharidewhichcouldinhibitstarchretrogradation.
TheeffectsofchitosanonretrogradationpropertiesofwheatstarchwerestudiedandthepossibleinfluencemechanismofchitosanonwheatstarchwasinvestigatedbyX-raydiffraction(XRD)andFourierTransformInfraredSpectroscopy(FT-IR)inthepaper.
Resultsshowedthatiodinebluevalueincreasedwhilegelstrengthofwheatstarchdecreasedwithincreasingchitosancontent.
Meanwhilethegelatinizationtemperature,retrogradationenthalpyandretrogradationrateofwheatstarchreducedslightlyfrom62.
71to55.
85℃,4.
68J/gto2.
41J/gand54.
47%to19.
87%respectively.
Distinctivedifferencesbetweenwheatstarchgelswithoutorwithchitosanwereobserved.
Furthermoretheintensityofapeakcloseto16.
9°ofwheatstarchsampleswithchitosanweredecreasedandnarrowedcomparedwiththenativestarch,indicatingthedisappearanceofthetypicalB-pattern,whichimpliedthatchitosancouldretardtherecrystallizationortheretrogradationbehaviorofgelatinizedstarch.
Afterblendedwithchitosan,thestretchingvibrationpeakofhydroxylofwheatstarchshiftedfrom3427.
78to3419.
65,whichindicatedmorehydrogenbondsformedbetweenchitosanandwheatstarch.
KEYWORDSWheatstarch;Chitosan;Retrogradation;Properties;Effects.
12130EffectsofChitosanonretrogradationpropertiesofwheatstarchBTAIJ,10(20)2014INTRODUCTIONStarchisanimportantstructuralcomponentofwheatflour,whichstronglyinfluencesthetextureandshelflifeofthehostproducts.
Stalenessofwheatflourproductsisacomplexphenomenoninvolvingmanyfactorsandprocesses,buttheretrogradationofgelatinizedstarchduringstorageisbelievedtobeanimportantcontributor[1].
Thetermretrogradationreferstothechangesthatoccuringelatinizedstarchuponcooling,whichimpliesfullyreversiblerecrystallizationinthecaseofamylopectinandpartialirreversiblerecrystallizationinthecaseofamylase[2].
Retrogradationresultsinlossofimportantsensoryparametersofmanyfoodproductsmadefromwheatflour,likeflavorandtexture,andleadsmainlytoanincreaseofcrumbfirmnessandlossoffreshness.
Atpresent,manyresearchersareexploringtheuseofpolysaccharidestocontroltheretrogradationrateofstarch-basedproducts.
Thereareanumberofreportsconcerningtheapplicationofnaturalpolysaccharidestomodifytheretrogradationbehaviorofstarch,includingmixturesofteapolysaccharidesandpullulan,flaxseedgumandxanthan,soybean-solublepolysaccharideandgumarabic[1,3-6].
Chitosan[-(1,4)-2-amino-2-deoxy-D-glucopyranose]isacarbohydratederivedbydeacetylationofchitin,whichisthesecondmostabundantbiopolymerinnaturenexttocellulose[7].
Asanatural,nontoxicandbiodegradablebiopolymer,chitosanhasreceivedconsiderableattentioninthefoodindustryduetoitsphysiologicalproperties,nutritionalandbiochemicalactivitiesandhasbeenapprovedasafoodadditiveinmanycountries[8].
Weixin-linreportedthatchitooligosaccharides(averagemolecularweightof1390,degreeofdeacetylationof91%)hadobviousresistancetostarchaging[9].
Wuyueinvestigatedtheeffectofchitooligosaccharidesontheretrogradationofintermediateamylosericestarchandfoundthemolecularsizeofchitosandetermineditsanti-retrogradationcapabilityandchitosanwithmolecularweightbetween5kand10khadthebestanti-retrogradationabilitywhilechitosanwithmolecularweightunder5khadnoeffect[10].
KerchGhadtheoppositeconclusionthatChitosanoligosaccharidesandlowmolecularweightchitosanincreasebreadcrumbstalingrate[11].
Chitosanasfoodadditivewasseldomappliedinthewheatproducts.
Furthermoreapplicationofchitosaninfunctionalfoodsisanareaofparticularinterest.
Theaimofthisstudyistoinvestigatetheeffectofchitosanontheretrogradationpropertiesofwheatstarchandthepossiblemechanisminvolvedchitosanandwheatstarch.
MATERIALSANDMETHODSMaterialsWheatstarchwaspurchasedfromBaodingbrewingco.
,LTD(Shanghai,China).
Solublechitosan(averagemolecularweightof5000,degreeofdeacetylationof95%)waspurchasedfromgoldenshellpharmaceuticalco.
,LTD(Zhejiangprovince,China).
AllotheranalyticallaboratorychemicalsandreagentswerepurchasedfromSinopharmChemicalReagentCompany(Shanghai,China).
IodinebluevalueThebluevalue(BV)wasdeterminedaccordingtothemethodofZengJiewithsomemodifications[12].
Thesample(0.
10g)wasdispersedinboilingwaterfor10minandcooledrapidly.
Starchdispersion(5ml)wastakenina100mLvolumetricflaskalongwith50mLofdeionizedwater,1mol/Laceticacidsolution1mLandiodinereagent1mL(1.
0mgI2/mLand10.
0mgKI/mL).
Thevolumewasmadeupto250mLwithdistilledwaterandmixedimmediately.
Thenstanding30minandcolored.
Controlsolutionsweremadeinthesamewaybutwithoutsample.
Allsampleswerescannedat620nmwithanUV1100spectrophotometer(Mapadainstrument,Shanghai,China).
TheabsorbancevalueofpergramofstarchwasrecordedastheBV.
TexturecharacteristicsChitosanandwheatstarch(0/12、1/48、1/36、1/24、1/12)werepreparedandtransferredtoglassvials,coveredwithaluminumfoil,andheatedinawaterbathat95Cfor20min.
Afterbeingheated,theformedgelswerecooledandstoredat4Cfor24hbeforetest.
Priortothegelstrengthmeasurement,gelsampleswereallowedtoequilibrateattheroomtemperature(25±1C)for30min.
Gelswerepenetratedwithaflat-facedstainlesssteelprobe(10mmdia)attachedtoaModelTAXT2textureanalyzer(StableMicroSystemsLtd.
,Surry,U.
K.
)atacrossheadspeedof0.
3mm/s,Pre-andpost-testspeedwerecontrolledat1.
00mm/s.
Thedistanceofthecompressionwassetat10mm.
Thepenetrationforcewhichwasthepeakforcerequiredtorupturethegelswasexpressedasthegelstrength[8].
Differentialscanningcalorimetry(DSC)ThegelatinizationandretrogradationpropertiesofthesamplesweredeterminedfromtheDSCcurves.
DSCmeasurementswerecarriedoutusingaDSC-Q100apparatus(TAinstrumentCo.
Ltd.
,American).
Theweightratioofdrywheatstarchtowaterwasmaintained1:2andchitosan/wheatstarchmixingratioswere0/12、1/48、1/36、1/24、1/12.
Sampleswereplacedinascrew-topglassbottleanddispersedindistilledwaterbystirringfor2hatroomtemperatureusingamagneticstirrer.
Thecalorimeterwascalibratedwithanindiumstandard.
AllsampleswerepreciselyweighedonanaluminumDSCpan.
Thepanwassealedusingasample-encapsulatingpress.
Theheatingprogramincreasedthesampletemperaturefrom30℃to130℃atarateof5℃/min,followedbycoolingto30℃atthesamerate.
Heatingandcoolingwereperformedinanatmosphereofnitrogengas.
SamplesofthedispersionswereweighedintoanaluminumDSCpan.
Theonsettemperature(To),peaktemperature(Tp),andconclusiontemperature(Tc)weredeterminedfromthefirst-runheatingDSCcurves.
Thegelatinizationenthalpywasevaluatedbasedontheareaofthemainendothermicpeak.
Afterthefirst-runheating,thegelatinizedsampleswerecooledto30℃intheinstrumentandstoredat4℃for4days.
ThestoredsampleswerereheatedBTAIJ,10(20)2014LiuFang-Lietal.
12131toexaminetheeffectsofchitosanonretrogradation.
Theretrogradationratiowascalculatedbydividingthere-gelatinizationenthalpyofthesecondheatingrunbythegelatinizationenthalpyinthefirstheatingrun[1].
MicrostructureThewheatstarchintheabsenceorpresenceofchitosanwerepastedandagedfor7days.
Thenthesampleswerefreeze-driedinafreeze-dryer(Scientz-10N,China)for24hours.
Microstructuresofthefreeze-driedsampleswereobservedusingSEM(Quanta-200,FEI,Netherlands)atanacceleratingvoltageof25KV[13].
X-raydiffractionTherecrystallizationanalysisofthegelatinizedsamplesintheabsenceorpresenceofchitosanwascarriedoutusinganX-raydiffractometer(GeminiE,Agilent,England).
Thesampleswerestoredfor2weeksindesiccatorscontainingP2O5andpulverizedbeforetesting.
Theinstrumentwasoperatedat40kVand30mA.
DiffractogramswereobtainedusingCu-Karadiation,scanningfrom5°2èto35°2èatarateof4°/minandastepsizeof0.
3mm.
OriginPro8.
0SoftwarewasusedtoanalyzethediffractogramsaccordingtothemethodofWuyue[2].
FouriertransforminfraredspectroscopyToperformFT-IRmeasurement,thedriedretrogradedwheatstarcheswithandwithoutchitosan(Theratioofchitosan:wheatstarch1:12)withweightof2mgwerefirstgroundintoflourandthendispersedin200mgKBr(pelletprocedure).
KBrpelletizedstarchsampleswereanalyzedusingaNicolet5700infraredspectrometerintherange4000to400cm1.
TheIRspectraforstarchtreatedwithandwithoutalkaliproteasewererecordedonadiamondplatewith32scansandaresolutionof4cm1[14].
StatisticalanalysisAlldeterminationswererepeatedintriplicate,andthemeanvaluesandSDswerereported.
RESULTSANDDISSICUSIONEffectsofchitosanoniodinebluevalueofwheatstarch0.
000.
020.
040.
060.
080.
104812162024iodinebluevalue(%)chitosanconcentrationFigure1:EffectsofchitosanadditiononIodinebluevalueofwheatstarchFigure1showedthebluevalueofwheatstarchwithdifferentadditionofchitosan.
Withtheadditiondoseofchitosanincreasing,thebluevalueaddedcomparedwiththecontrol.
Theseresultsindicatedthatthecontentoffreestarchincreasedandchitosaninhabitedtheretrogradationofwheatstarch.
Effectsofchitosanongelstrengthofwheatstarchgels0.
000.
020.
040.
060.
080.
10100150200250300gelstrength(Pa)chitosanconcentrationFigure2:Effectsofchitosanadditionongelstrengthofwheatstarchgels12132EffectsofChitosanonretrogradationpropertiesofTofurtherelucidatetheroleofchitosanongelpropertieslevelsofchitosanswereevaluatedbygelstrengthgelsdecreased.
Starchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadinfluenceonthefoodquality.
Gelstrengthgels,whichsuggestedpossiblewheatstarchtexturecharactersandrestrainedtheretrogradationEffectsofchitosanonthermalpropertiesofwheatstarchTABLE1:EffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchsamplesT.
(℃)12/048/136/124/112/157.
96±0.
0446.
39±0.
0941.
75±0.
0340.
89±0.
0239.
85±0.
0362.
71±0.
0560.
76±0.
0260.
40±0.
0457.
16±0.
0355.
85±0.
06DifferentialScanningCalorimetrybehaviourofstarchgelatinizationandretrogradation.
asgelatinizationenthalpyisnecessarytobreakdomeltingenthalpyprovidesaquantitativemeasureoftheenergyusedtoenthalpytogelatinizationenthalpyisconsideredtobeorecrystallization[2].
FromTABLE1,To,TpandTcweresignificantlyretrogradationratioofwheatstarchdecreased.
otherresearchersandcouldbeinterpretedasfollows:interactdirectlywithstarchbyintermolecularhydrogenbondstostaChitosanwasefficienttoretardstarchretrogradationEffectsofchitosanonmicrostructureofwheatstarchgelswheatstarchFigure3:MicrostructureofwheatSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweengelswithoutorwithchitosan(1/12)wereobservedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographofwithchitosanadded(right)showedawellmicrostructuralchangeshelpedtoexplainthesedifferencesbetweenuniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocstructurewithlargepores.
TheseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandchitosanlikeabinderdisperseduniformlyandtightlyassociatedinthegelnetworkEffectsofChitosanonretrogradationpropertiesofwheatstarchTofurtherelucidatetheroleofchitosanongelpropertiesofwheatstarch,gelspreparedwithvariousconcentrationgelstrength.
Withincreasingamountofchitosanadded,gelstrengthStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadofwheatstarchgelsdecreasedproportionallywithmorechitosanwheatstarch-chitosaninteractions.
Therefore,itwaspresumedthatchitosanretrogradationofwheatstarch.
EffectsofchitosanonthermalpropertiesofwheatstarchgelsEffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchTp(℃)Tc(℃)Hg(J/g)retrogradationrati62.
71±0.
0560.
76±0.
0260.
40±0.
0457.
16±0.
0355.
85±0.
0672.
10±0.
0771.
34±0.
0370.
32±0.
0870.
19±0.
0266.
88±0.
054.
68±0.
124.
01±0.
093.
53±0.
233.
31±0.
162.
41±0.
0854.
47±0.
1240.
04±0.
2336.
70±0.
1527.
96±0.
0819.
87±0.
13ScanningCalorimetry(DSC)hasproventobeoneoftheeffectivemethodstodeterminethethermalbehaviourofstarchgelatinizationandretrogradation.
Duringthecourseofgelatinization,acertainquantityofheatexpressedgelatinizationenthalpyisnecessarytobreakdownthecrystallineareasofstarch.
Astoretrogradedstarch,thevalueofprovidesaquantitativemeasureoftheenergyusedtomelttherecrystallizedstarch.
Theenthalpytogelatinizationenthalpyisconsideredtobeoneusefulindicatortodeterminetheweresignificantlydecreasedwithincreasingtheadditiondoseofchitosan.
ofwheatstarchdecreased.
Thedecreaseofgelatinizationtemperatureswereconsistentwiththereportsofandcouldbeinterpretedasfollows:theavailablewaterwasreducedbythehydrationandintermolecularhydrogenbondstostabilizethecrystallineregionsofretardstarchretrogradation.
Effectsofchitosanonmicrostructureofwheatstarchgelschitosan-wheatstarchmixtureMicrostructureofwheatstarchandchitosan-wheatstarchmixtureSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweenwereobserved.
Thestructureofwheatstarchgels(left)showedgranularaggregatedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographof)showedawell-structuredmatrixwithahighlyinterconnectednetworkofstrands.
Thesemicrostructuralchangeshelpedtoexplainthesedifferencesbetweenwheatstarchgelswithoutorwithuniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocstructurewithlargepores.
Theseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandhitosanlikeabinderdisperseduniformlyandtightlyassociatedinthegelnetwork.
BTAIJ,10(20)2014,gelspreparedwithvariousconcentrationadded,gelstrengthofwheatstarchStarchretrogradationcouldincreasefood'shardnessandreducefood'sdigestionrate,whichhadbadwithmorechitosanincorporatedinchitosancouldenhancetheEffectofdifferentchitosanadditiononthermalpropertiesofwheatstarchduringstorageretrogradationratio(%)54.
47±0.
1240.
04±0.
2336.
70±0.
1527.
96±0.
0819.
87±0.
13theeffectivemethodstodeterminethethermalgelatinization,acertainquantityofheatexpressedretrogradedstarch,thevalueofmelttherecrystallizedstarch.
Theratioofmeltingneusefulindicatortodeterminethedegreeofstarchwithincreasingtheadditiondoseofchitosan.
Andtemperatureswereconsistentwiththereportsoftheavailablewaterwasreducedbythehydrationandchitosancouldcrystallineregionsofwheatstarchgels[5,13].
wheatstarchmixturemixtureSEMprovidedstructuralinformationaboutgels.
AsshowninFigure3,distinctivedifferencesbetweenwheatstarch)showedgranularaggregatedstructurewithinthematrix,whichseemedlesslinkageandsomewhatdiscontinuous.
Themicrographofwheatstarchgelsetworkofstrands.
Thesegelswithoutorwithchitosan.
Afine,uniformstructurewouldprobablyresultinmoreabsorptivecapacityandbetterretentionofwatercomparedtocoarsestructurewithlargepores.
TheseresultsshowedthatinteractionpossiblyexistedbetweenchitosanandwheatstarchandBTAIJ,10(20)2014LiuFang-Lietal.
12133Effectsofchitosanoncrystallinityofwheatstarchgels510152025303550100150200250300Intensity(counts)2-Theta12/012/1Figure4:X-raydiffractionspectraofwheatstarchandchitosan-wheatstarchmixtureInvestigationsusingXRDwereconductedtofurtherandpowerfullyprovethepreventingeffectofchitosanontheretrogradation.
TheXRDpatternsandcorrespondingcrystallinityareshowninFigure4.
OncenativeRSisgelatinized,itdevelopsa"B-type"diffractionpatternduringaging.
Retrogradedstarchgivesa"B-type"diffractionpatternandthisisaccompaniedbygradualincreasesinrigidityandphaseseparationbetweenthepolymerandthesolvent(syneresis).
B-typecrystallinityischaracterizedbyawell-definedpeakat16.
9°(2è).
Theformationofthispeakwastheresultofthecrystallizationoftheamorphousstarchmelt,mainlyoftheamylopectinfractionthatincreasedduringstorage[2].
AsshowninFigure4,theintensityofapeakcloseto16.
9°ofwheatstarchsampleswithchitosanweredecreasedandnarrowedcomparedwiththenativestarch,indicatingthedisappearanceofthetypicalB-pattern,whichimpliedthatchitosancouldretardtherecrystallizationortheretrogradationbehaviorofgelatinizedstarch.
Effectsofchitosanoninfraredspectraofwheatstarchgels0500100015002000250030003500400045000.
550.
600.
650.
700.
750.
80ransmittancewavenumers(cm-1)a:12/0b:12/1Figure5:Fourierinfraredspectraofwheatstarchandchitosan-wheatstarchmixtureFigure5showedtheIRspectraofretrogradedwheatstarcheswithoutandwithchitosan.
Thebandabsorbanceinstarchhavebeenassignedandmatchedwiththevibrationalmodesofthechemicalbondsandthestructuresofstarchmolecules[14].
IRspectraindicatedthattherewasnodifferencebetweenthewheatstarchandchitosan-wheatstarchmixture,whichsuggestedthattherewasnosignificanteffectofchitosanonthestructureofwheatstarch.
ButHydrogenbondspossiblyformedbetweenwheatstarchandchitosanduringretrogradation.
Formationofhydrogenbondsinretrogradedwheatstarchisidentifiedbylow-fieldshiftofwavenumbersforstretchingvibration(3415and3387cm1for–OH).
Afterblendedwithchitosan,thehydroxylstretchingvibrationpeakshiftedfrom3427.
78to3419.
65fromIRspectrawhichsuggestedthatmorehydrogenbondsformedinthesesamples.
CONCLUSIONSFromtheoverallresults,itcouldbeconcludedthattheadditionofchitosantowheatstarchcouldsignificantlyretardretrogradation.
Watermigrationcontributedalottothestarchretrogradation,whichneedsfurtherstudy.
Additionofchitosan12134EffectsofChitosanonretrogradationpropertiesofwheatstarchBTAIJ,10(20)2014towheatproductscreatesanopportunitytocombinebeneficialtechnologicalpropertieswithbeneficialbiologicalhealthpromotingproperties.
Hence,chitosancouldbesuitabletoaddtowheatproductsandsimultaneouslyenhancequalityandnutrition.
Thesestudiesareimportantforthedevelopmentofchitosanasthefoodadditiveinwheatproductstomakethemcompetemoreeffectivelyinthemarkets.
ACKNOWLEDGMENTSThisworkwassupportedbytheprojectofeducationaldepartmentofHenanprovinceandZhengzhouLightIndustryUniversityFundforKeyTeachers.
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FoodResearchInternational,42,221-225(2009).
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ScienceandTechnologyofFoodIndustry,34,156-158(2013).
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