碱醇处理的木薯淀粉结晶结构的变化

碱醇处理的木薯淀粉结晶结构的变化 天然产物研究与开发NatProdResDev2007,19:25-28 文章编号:1001-6880(2007)01-0025-04 碱醇处理的木薯淀粉结晶结构的变化 徐立宏h,张本山,杨连生 华南理-l"大学化学科学学院;华南理工大学轻工与食品学院,广州510640 摘要:木薯淀粉在一定温度下用乙醇和碱的混合液处理.用HC1中和,醇洗,最后在 50?左右的烘箱中干燥6 h,X射线衍射结果明经碱醇处理的木薯淀粉其微品,亚微晶,非晶的组成发生了 变化.不同的处理条件,结晶 组成的变化不同.较低浓度的醇,较高浓度的碱或较高反应温度得到非品化程度高 一些的淀粉.在偏光显微 镜下观察到较少的偏光十字,表明淀粉的结晶结构发生了变化. 关键词:微晶;亚微晶;非晶 中图分类号:Q946.91文献标识码:A CrystallineStructureChangesofTapiocaStarchGranule byAlcoholic-Mk~neTreatment xuLi—hong',ZHANGBen—shah2, YANGLian—sheng2 CoReofChemistryScience;CollegeofLightIndustryand FoodScienceSouthChinaUni"ersityofTechnology,Gnangzhou510640,China Abstract:TapiocastarchwastreatedwithamixtureofethanolandNaOHsolutionsatacontroll edtemperature.Thetrea— tedstarchwastllenneutralizedwithHC1.washedwithethanol.anddriedat50? f0r6h.X.raydiffractionexperiment showedthattheproportiononmierocrystal,submierocrystalandnon-crystalofthetapiocast archtreatedbyalcoholic— alkalinewaschanged.Lowerconcentrationofethanol,higherconcentrationofNaOH,orhig hertemperaturegavethere— suhingstarcheshighernon?erystallinity.LessMaltesecross~wereobservedunderpolarized —lightmicroscopy,indicating thechangesofcrystallinestructure. Keywords:mierocrystal;submierocrystal:non.crystal Introduction Starchisakindofnaturalcrystallinehighpolymer.The starchgranuleiscomposedofmicrocrystal,submicro— crystalandnon—crystal【. Methodsofstudyingstarch crystallinepropertiesincludeX—raydiffraction,micros. copy,scanningelectronmicrographandDSC[2.5】. Late studiesoncrystallinestarchwerereported[?6_2..Theo— riginalstudyofnon—crystallinestarchistoobtainthe non—crystallinestarchstandardfordeterminingcrystal— linity.Starchwastreatedinball—millover24handthe crystalstructureofstarchisdestroyed.In1994,S. VeelaertreportedthatMaltesecrosseslostwhendialde— ReceivedJune5,2006;AcceptedNovember6, 2006 FoundationItem:ThisworkwasfinanciallysupportedbyNationalNatu. ralScienceFoundation(29976016). CorrespondingauthorTel:86-20-87113637;E-mail:chlhxu@scut.edu. cn hydestarcheswerepreparedbyoxidationwithperio— date[.DoctorStuereportedthephenomenaofbire— fringencelossofstarchwhentreatingthestarchsuspon— dedinwaterwithultra—highpressure[引. ShinjiTama. kireportedstarchcrystallinestructuregraduallydisap— pearedbyball-mill320htreatment[引.ZhangBen— shanreportedstarchnon—crystallizationwhenstarch cross—linkedwithphosphomsoxychloride[. Thepurposeofthepresentstudywastoinvestigatethe proportionchangesamongmicmcrystal,submicmcrystal andnon?-crystalinalcoholic??alkalinetreatedtapioca starch.Theeffectsofalcohol.andalkaliconcentra— tions,andtemperaturewerestudied. MaterialsandMethods Materials TapiocastarcheswereobtainedfromGuangxiMingyang BiotechCo.,Ltd..Otherchemicalswereallreagent NatProdResDevVo1.19 gradeandwereusedwithoutfurthertreatment. Treatmentoftapiocastarch Tapiocastarchesweretreatedwithamixtureofethanol andNaOHsolution(3mol/L)atdifferentproportions andat25,30,or35oC. Tapiocastarches(25g,dsb)weresuspendedin137g of4O%(W/W)ethanolsolutionina250mLbeaker equippedwithamechanicalstirrer.NaOHsolution(3 mol/L,75g)wasweiedandaddedat70D/min. Themixturewasthenallowedtostandfor15minwith gendestirring.Additional25mL40%(W/W)ethanol solutionwasaddedslowlytothestarchsuspension.Af- ter10minofstirring,theslurrywasleftatroomtem— perature.FilteredusingBuchnerfunne1.estarchwas resuspendedinaqueous40%(W/w)ethanolsolution andneutralizedwithHClf3mol/Linabsoluteetha— nol1.Theneutralizedstarchwaswashedwith75%eth— anolsolutions.Itwasthenwashedinabsoluteethanol anddriedinanovenat5O?f0rover6h.Thedried 350 300 25o 200 g150 堇1OO 5O 0 . 50 350 3oo 250 言200 芒150—. 100 50 O 01O2O30405060 Diffractionangle(28) starchwassmashedusingpulverizerandsievedwith 125txmscreenandstoredindrieratroomtemperature forfurtheranalyses. X-Raydiffraction X—Raydiffractionpatternsofstarchesweretakenona diffractometerwithaCuX-raytubeandanickelfoil filteroperatedat30kVand30mA.ex-raypatterns ofthemixtureswererecorded,andthescanningregion ofthediffractionangle(2口)wasfrom4.to60.. Microscopy LightmicrographsweretakenusingOlympusVanox BHS一2microscopyoperatinginbrightfieldandpolariza— tionmodes. ResultsandDiscussion X-Rayanalysis Starchiscomposedofmicrocrystal,submicrocrystaland non—crysta1.ThetheoryofX—raydiffractionindicates 350 3o0 250 200 g150 羔100 5O O . 50 Diffractionangle(28)Diffractionangle(28) 350 3OO 250 2o0 150 100 50 0 - 50 350 3oo 250 言200 芒150— 100 50 O 0102030405060 Diffractionangle(28) Dractionanale(28) Fig.1X-raydiffractionpatternsofalcoholic-alkalinetreatedstarch 0.Nativetapiocastarch;1—6.Alcoholic—alkalinetreatedtapiocastarch 鲁?ca1ul ?c91ul 丽c.1ul Vo1.19XULi.hongetal:CrystallineStructureChangesofTapiocaStarchGranulebyAlcohol ic'AlkalineTreatment thatverysmallorimperfectcrystals fraction.Incontrast,perfectcrystals tionpeak.AccordingtoDr. givebroadeneddif- givesharpdiffrac- ZhangBenshan'smeth- od[引. anX.raypatternisdividedintothreearea:mi— crocrystal(C);submicrocrystal(S);non-crystal(N). Thevhavedifferentcharacteristics.Cshowssharp peak,SandNshowbroadenedpeak,non-crystalpro. ducesdispersivediffractionpeak.Inadditiontoprovi- dinginformationaboutthecrystalstructureofstarch granules,X—raydiffractioncangiveinformationabout therelativeamountsofcrystallineandamorphouspha- ses.ByintegratingtheX-rayscatteringintensitysepa. ratelyoverthepeaksandoverthebackground,theval. uesobtainedcanbeinterpretedas"microcrystallini- ty","submicrocrystallinity"and"non-crystallinity". X.raydiffractionpatternsarepresentedinFig.1. Thecompositionsofthetreatedstarchareobtained fromcomputerprogram.Theresultsshowthatthecon tentofmicrocrystallinestructuredecreasecompared withnativestarch.Submicrocrystalalsodecreasesex— ceptsample1.Theamountsofnon-crystal causestaTchisaweakionexchanger['】 increase.Be一 , whenstarch moleculeswereplacedinastrongalkalinesolution, protonsofthe-OHgroupweredissociatedandleftneg? ativechargesonstarchmolecules.Therepulsionbe— tweennegativechargesresultedinswellingofstarch granules.Theswellingofthegranulesexertedatension onneighbouringcrystallitesofstarchmoleculesand tendedtodistortthem[81.Furtllerswellingledtothe breakupofpartofmicrocrystallinestructureandsome partofmicrocrystalorsubmicrocrystaltochangeto non—crysta1.Thedifferentalcoholic—alkalinetreatments areshowninr1,able1. Table1Treatmentofstarchnon-cry~nllDation Table2Compositionofstarchbyalcoholic.alknlinetreat. ment O l 2 3 4 5 6 16.79 14.12 14.39 13.26 l3.76 9.2 13.84 29.53 26.16 31.65 2o.75 27.3l 28.22 23.12 46.32 40.28 46.04 34.01 41.07 37.42 36.96 5368 59.72 53.96 65.99 58.93 62.58 63.04 C.Microcrystal;S.Sub.microcrystal;C+s.Crystal;N.Non-crystal 0.Nativetapiocastarch;1—6.Alcoholic-alkalinetreatedtapioca starch Thenon.crystalcontentsofsample3,5and4were 65.99.62.58and58.93%(Table2),respectivelyfor thetreatment34,29and20?(Table1).Therefore, highertemperaturegavethestarchesthehighernon. crystallinity. Thenon—crystalcontentvariedwithdifferentconcentra- tionsofethano1.Whenethanolconcentrationincreased from5.5x(sample1)to7.0x(sample2),thenon. crystalcontentdecreasedfrom59.72%to53.96%. Highconcentrationsofethanolrestrictedthestarch granuleswelling. Alkalinewasanotherimportantfactorforthechangesof crystallinestructure.Treatmentwithagreatervolumeof NaOHsolution(3mol/L)ledtostarcheswithhigher non.crystallinity.HigherNaOHconcentrationsin- creasedtheswellingofthegranules.Therefore,agrea. ternon.crystallinity(sample6)wasobservedthanthe contrast(sample4).Compositionchanges tapiocastarcharelistedinTable3. ofthetreated Table3CompositionchangesofalcohoHc?811~etreated starch Polarisationmicroscopy Polarizedlightmicrographsofthestarchbyalcoholic. alkalinetreatmentshowedthelOSSoftheMaltese—CroSS NatProdResDelIV01.19 thanthatofnativestarch.Fig.2showedthatthetreated starchgranulesremainedintact. Fig.2Polarizedfightmicrophotosofstarchesbyalco- holic.alkalinetreatment 0.Nativestarch;4.Mcohohc-alkalinetreatedtapiocastarch Conclusion Alcoholic—?alkalinetreatmentresultedinthes~rchcrys-. tallinestructurechanges.Highertemperature,lower concentrationsofethanol,andgreaterconcentrationsof NaOHproducedthestarchwithhighernon-?crystallini.. t)r. 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