Starch yog hu ua polysaccharide. Qhov no txhais tau hais tias nws muaj monosaccharides txuas hauv cov saw ntev. Qhov tseeb, nws yog kev sib xyaw ntawm ob yam khoom sib txawv ntawm cov khoom siv polymeric: hmoov txhuv nplej siab muaj amylose thiab amylopectin. Lub monomer nyob rau hauv ob qho tib si chains yog ib tug qabzib molecule, txawm li cas los xij, lawv txawv heev hauv cov qauv thiab cov khoom.
Tag nrho pawg
Raws li twb tau hais lawm, ob qho tib si amylose thiab amylopectin yog cov polymers ntawm alpha-glucose. Qhov txawv yog nyob rau hauv qhov tseeb hais tias amylose molecule muaj ib tug linear qauv, thiab amylopectin yog branched. Thawj yog ib feem ntawm cov hmoov txhuv nplej siab soluble, amylopectin tsis yog, thiab feem ntau, cov hmoov txhuv nplej siab hauv dej yog cov tshuaj colloidal (sol), uas cov yaj ib feem ntawm cov khoom yog nyob rau hauv sib npaug nrog cov undissolved ib.
Ntawm no, rau kev sib piv, cov qauv qauv ntawm amylose thiab amylopectin tau muab.
Amylose yog soluble vim yog tsim ntawm micelles - cov no yog ob peb lub molecules sib sau ua ke nyob rau hauv xws li ib txoj kev uas lawv hydrophobic kawg tau muab zais rau hauv, thiab lawv cov hydrophilic kawg yog muab zais rau sab nraum rau kev sib cuag nrog dej. Lawv nyob hauv qhov sib npaug nrog cov molecules tsis sib sau ua ke hauv cov khoom sib xyaw.
Amylopectin kuj muaj peev xwm tsim cov tshuaj micellar, tab sis kom tsawg dua, thiab yog li xyaum ua kom tsis muaj dej txias.
Amylose thiab amylopectin hauv cov hmoov txhuv nplej siab yog nyob rau hauv qhov sib piv ntawm kwv yees li 20% ntawm yav dhau los mus rau 80% tom kawg. Qhov ntsuas no nyob ntawm seb nws tau txais li cas (hauv cov nroj tsuag uas muaj cov hmoov txhuv nplej siab sib txawv, feem pua kuj txawv).
Raws li tau hais lawm, tsuas yog amylose tuaj yeem yaj hauv dej txias, thiab txawm tias tom qab ntawd tsuas yog qee qhov, tab sis hauv dej kub ib qho muab tshuaj yog tsim los ntawm cov hmoov txhuv nplej siab - ntau dua lossis tsawg dua homogeneous nplaum pawg ntawm cov hmoov txhuv nplej siab o.
Amylose
Amylose muaj cov piam thaj molecules txuas rau ib leeg los ntawm 1, 4-hydroxyl bonds. Nws yog ib tug ntev, unbranched polymer nrog qhov nruab nrab ntawm 200 ib tus neeg cov piam thaj molecules.
Hauv cov hmoov txhuv nplej siab, cov saw amylose yog coiled: txoj kab uas hla ntawm "qhov rais" hauv nws yog kwv yees li 0.5 nanometers. Ua tsaug rau lawv, amylose muaj peev xwm tsim cov complexes, cov khoom sib xyaw ua ke ntawm "tus tswv tsev" hom. Cov tshuaj tiv thaiv zoo ntawm cov hmoov txhuv nplej siab nrog iodine belongs rau lawv: amylose molecule yog "tus tswv", iodine molecule yog "tus qhua", muab tso rau hauv lub helix. Lub complex muaj xim xiav khaus thiab yog siv los kuaj ob qho tib si iodine thiab starch.
Hauv cov nroj tsuag sib txawv, feem pua ntawm amylose hauv cov hmoov txhuv nplej siab tuaj yeem sib txawv. Hauv cov nplej thiab pob kws, nws yog tus qauv 19-24% los ntawm qhov hnyav. Cov hmoov txhuv nplej siab muaj 17% ntawm nws, thiab tsuas yog amylose muaj nyob hauv cov kua txiv hmab txiv ntoo - 100% pawg pawg.
Nyob rau hauv paste, amylose ua cov soluble ib feem, thiab qhov no yog siv nyob rau hauvanalytical chemistry rau kev sib cais ntawm cov hmoov txhuv nplej siab rau hauv feem. Lwm txoj kev, starch fractionation yog nag lossis daus ntawm amylose nyob rau hauv daim ntawv ntawm complexes nrog butanol los yog thymol nyob rau hauv boiling daws nrog dej los yog dimethyl sulfoxide. Chromatography siv tau cov cuab yeej ntawm amylose rau adsorb rau cellulose (nyob rau hauv lub xub ntiag ntawm urea thiab ethanol).
YAmylopectin
Starch muaj cov qauv tsim. Qhov no tau ua tiav vim qhov tseeb tias, ntxiv rau 1 thiab 4-hydroxyl bonds, cov piam thaj molecules hauv nws kuj tsim cov ntawv cog lus ntawm 6 pawg cawv. Txhua qhov "thib peb" daim ntawv cog lus hauv cov molecule yog ib ceg tshiab hauv cov saw hlau. Cov qauv dav dav ntawm amylopectin zoo li ib pawg hauv cov tsos, macromolecule tag nrho muaj nyob rau hauv daim ntawv ntawm cov qauv kheej kheej. Tus naj npawb ntawm cov monomers nyob rau hauv nws yog kwv yees li ntawm 6000, thiab qhov hnyav molecular ntawm ib molecule ntawm amylopectin yog ntau loj dua li ntawm amylose.
Amylopectin kuj tsim ib qho kev sib xyaw ua ke (clathrate) nrog iodine. Tsuas yog nyob rau hauv rooj plaub no lub complex yog xim liab-violet (ze rau liab) xim.
tshuaj muaj zog
Cov tshuaj lom neeg ntawm amylose thiab amylopectin, tshwj tsis yog kev cuam tshuam nrog iodine twb tau tham lawm, yog tib yam nkaus. Lawv tuaj yeem muab faib ua ob ntu: cov yam ntxwv ntawm cov piam thaj, uas yog, tshwm sim nrog txhua tus monomer cais, thiab cov kev cuam tshuam cuam tshuam rau kev sib raug zoo ntawm monomers, xws li hydrolysis. Yog li ntawd, ntxiv peb yuav tham txog cov tshuaj lom neeg cov hmoov txhuv nplej siab raws li kev sib xyaw ntawm amylose thiab amylopectin.
Starchhais txog cov piam thaj tsis txo qis: tag nrho cov glycosidic hydroxyl (piv txwv li hydroxyl ntawm 1 carbon atom) koom nrog cov ntawv cog lus sib cuam tshuam thiab yog li tsis tuaj yeem muaj nyob rau hauv cov tshuaj tiv thaiv oxidation (piv txwv li, Tollens test - cov tshuaj tiv thaiv zoo rau pawg aldehyde, lossis kev cuam tshuam nrog Felling's. reagent - freshly precipitated hydroxide tooj liab). Preserved glycosidic hydroxyl, tau kawg, muaj (ntawm ib kawg ntawm cov saw hlau polymer), tab sis nyob rau hauv me me thiab tsis cuam tshuam cov khoom ntawm cov khoom.
Txawm li cas los xij, ib yam li ib tus neeg cov piam thaj molecules, cov hmoov txhuv nplej siab tuaj yeem tsim cov esters nrog kev pab los ntawm cov pab pawg hydroxyl uas tsis koom nrog kev sib raug zoo ntawm monomers: lawv tuaj yeem "dai" nrog methyl pawg, acetic acid residue., thiab lwm yam.
Tsis tas li, cov hmoov txhuv nplej siab tuaj yeem oxidized nrog iodine (HIO 4) acid rau dialdehyde.
Hydrolysis ntawm starch yog ob hom: enzymatic thiab acidic. Hydrolysis nrog kev pab ntawm enzymes belongs rau seem ntawm biochemistry. Lub enzyme amylase zom cov hmoov txhuv nplej siab rau hauv luv luv polymeric chains ntawm qabzib - dextrins. Acid hydrolysis ntawm starch yog ua tiav nyob rau hauv lub xub ntiag ntawm, piv txwv li, sulfuric acid: starch yog tawg tam sim ntawd mus rau lub monomer - qabzib.
Nyob hauv hav zoov
Nyob rau hauv biology, hmoov txhuv nplej siab feem ntau yog cov carbohydrate nyuaj thiab yog li siv los ntawm cov nroj tsuag ua ib txoj hauv kev khaws cov as-ham. Nws yog tsim thaum lub sij hawm photosynthesis (thaum xub thawj nyob rau hauv daim ntawv ntawm ib tug neeg cov piam thaj molecules) thiab tso rau hauv cov nroj tsuag hlwb nyob rau hauv daim ntawv ntawm cov nplej - nyob rau hauv noob, tubers, rhizomes, thiab lwm yam."khoom noj khoom haus" nrog embryos tshiab). Qee lub sij hawm cov hmoov txhuv nplej siab pom nyob rau hauv cov stems (piv txwv li, sago xibtes muaj cov hmoov txhuv nplej siab) los yog nplooj.
Nyob hauv tib neeg lub cev
Starch nyob rau hauv cov khoom noj uas nkag mus rau hauv lub qhov ncauj ua ntej. Nyob ntawd, ib qho enzyme uas muaj nyob rau hauv qaub ncaug (amylase) zom cov polymer chains ntawm amylose thiab amylopectin, tig lub molecules rau luv luv - oligosaccharides, ces lov lawv, thiab thaum kawg m altose tseem - ib tug disaccharide uas muaj ob lub qabzib molecules.
M altose tawg los ntawm m altase rau qabzib, monosaccharide. Thiab twb tau cov piam thaj los ntawm lub cev los ua lub zog.
