PHYSICOCHEMICAL CHARACTERISATION OF HEMICELLULOSES ISOLATED FROM SWEET SORGHUM STEM
The dewaxed sweet sorghum stem was sequentially treated with hot water, 6％ aqueous Na2ClO2 and 10％ KOH. The 10％ KOH-soluble hemicelluloses were graded by 20％, 40％, 60％, and 80％ ethanol, which released 5.7％, 21.2％, 3.5％, and 1.0％ hemicelluloses of the initial dry matter, respectively. The physicochemical properties and chemical composition of the five hemicellulosic subfractions were elucidated by a combination of monosaccharides composition, molecular weight, Fourier transform infrared (FT-IR), 1H and 13C NMR spectroscopies. The results revealed that all the hemicellulosic fractions were heteropolysaccharides containing xylose, arabinose, glucose, galactose, and 4-O-methyl-α-D-glucopyranosyluronic acid. The main monosaccharide of the water-soluble hemicellulosic subfraction was glucose (66.56％), while the four alkali-soluble hemicellulosic fractions comprised xylose, ranging between 62.75％ and 78.02％ of the total uronic acids and neutral sugars. Uronic acids, mainly 4-O-methyl-D-glucuronic acid, occurred in a small amount. Arabinose, galactose, and glucose were present as minor components. It was found that the hemicellulosic subfractions were composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylan. The Mw values of the alkali-soluble hemicellulosic subfractions obtained by precipitation with 40％ and 60％ ethanol (249 920 and 138 850 g mol-1) were much higher than those precipitated by 20％ and 80％ ethanol (45 780 and 25 460 g mol-1).
hemicelluloses sweet sorghum stem 13C NMR
She Diao Geng Zengchao Xu Feng Sun Runcang Gwynn Lloyd Jones Mark S. Baird
College of Resources and Environment, Northwest Agriculture and Forest University, Yanglin, 712100,C Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing 10083, China Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing 10083, China Stat The BioComposites Centre, University of Wales Bangor LL57 2UW, United Kingdom Department of Chemistry, University of Wales,Bangor LL57 2UW, United Kingdom
国际会议
广州
英文
269-272
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）