Single and multi-step carboxymethylation of water yam (Dioscorea alata) starch: Synthesis and characterization

DC FieldValueLanguage
dc.contributor.authorLawal, O. S.
dc.contributor.authorLechner, M. D.
dc.contributor.authorKulicke, W. M.
dc.date.accessioned2021-12-23T16:13:32Z-
dc.date.available2021-12-23T16:13:32Z-
dc.date.issued2008
dc.identifier.issn01418130
dc.identifier.urihttps://osnascholar.ub.uni-osnabrueck.de/handle/unios/10613-
dc.description.abstractWater yam (Dioscorea alata) starch was carboxymethylated by single and multi-step processes for nine times successively. Optimal degree of substitution (DS) of 0.98 and reaction efficiency (RE) of 70.5% were obtained in the single-step carboxymethylation at 40 degrees C, 3 h in isopropanol-water reaction mixture ratio 1:0.16. The ratio of sodium hydroxide and sodium monochloroacetate moles to anhydroglucose unit moles for the optimal DS and RE were 1.62 and 1.39, respectively. The DS increased progressively as the steps of carboxymethylation increased from 2 to 9 and an optimal DS of 2.24 was obtained. Initial increases in carboxymethylation step increased the RE progressively up to 82.1% after the seventh carboxymethylation step but declined with further increases in the carboxymethylation step. The wide angle X-ray diffractometry and the DSC revealed remarkable changes after carboxymethylation because starch crystallinity reduced significantly. Thermogram of native starch showed a characteristic three-step decomposition with 13.16%, 61.54% and 24.79% weight losses progressively while carboxymethyl derivative showed four decomposition stages with 9.86%, 36.57%, 3.04% and 23.07% weight losses progressively. Studies revealed that carboxymethylation improved thermal stability of the native starch. IR spectrometry revealed that carboxymethyl starch showed new bands at v = 1600, 1426 and 1324 cm(-1). The broad band C-13 NMR spectra of the ultrasonically degraded carboxymethyl starch showed a peak at delta = 180 ppm which was assigned to carbonyl carbon.
dc.language.isoen
dc.publisherELSEVIER
dc.relation.ispartofINTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
dc.subjectBiochemistry & Molecular Biology
dc.subjectcarboxymethylation
dc.subjectcharacterization
dc.subjectChemistry
dc.subjectChemistry, Applied
dc.subjectDERIVATIVES
dc.subjectFUNCTIONALIZATION
dc.subjectMOLECULAR-STRUCTURE
dc.subjectPHYSICOCHEMICAL PROPERTIES
dc.subjectPolymer Science
dc.subjectSWEET-POTATO
dc.subjectTUBER STARCHES
dc.subjectwater yam starch
dc.titleSingle and multi-step carboxymethylation of water yam (Dioscorea alata) starch: Synthesis and characterization
dc.typejournal article
dc.identifier.doi10.1016/j.ijbiomac.2008.02.006
dc.identifier.isiISI:000257039600004
dc.description.volume42
dc.description.issue5
dc.description.startpage429
dc.description.endpage435
dc.identifier.eissn18790003
dc.publisher.placeRADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS
dcterms.isPartOf.abbreviationInt. J. Biol. Macromol.
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