title: Successive alkali extraction and structural characterization of hemicelluloses from sweet sorghum stem.
abstract: Sweet sorghum stem was successively extracted with water at 90 °C, 0.3, 0.6, 1.0, 1.5, and 2.0% KOH aqueous solution, and 60% ethanol containing 2.5% KOH at 75 °C for 3 h, yielding 76.3% of the original hemicelluloses. Chemical composition and structural characterization of the seven hemicellulosic fractions obtained were comparatively investigated by a combination of HPAEC, GPC, FT-IR, (1)H-, (13)C-, HSQC NMR and TGA techniques. According to the spectral analysis, hemicelluloses from sweet sorghum stem are assumed to L-arabino-4-O-methyl-D-glucurono-D-xylan. In addition, the higher molecular weights of hemicelluloses resulted in a higher thermal stability of the samples. The present study suggests that successive alkali extraction is a promising approach for fractionation of hemicelluloses from sweet sorghum stem and to prepare hemicellulosic polymers with different branching and molecular weights.
authors: Institute of Biomass Chemistry and Technology, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors: Shao-Long
authors: SL
authors: Sun
authors: Jia-Long
authors: JL
authors: Wen
authors: Ming-Guo
authors: MG
authors: Ma
authors: Run-Cang
authors: RC
authors: Sun
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D000431:Ethanol / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry; D008970:Molecular Weight; D018547:Plant Stems / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification*; D017680:Potassium Compounds / Q000737:chemistry; D045868:Sorghum / Q000737:chemistry*; D013696:Temperature; D014574:Uronic Acids / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D011134:Polysaccharides; D017680:Potassium Compounds; D014574:Uronic Acids; D014867:Water; D000431:Ethanol; C007916:hemicellulose; C029943:potassium hydroxide