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Comparative study of hemicelluloses obtained by graded ethanol precipitation from sugarcane bagasse.
- Source :
-
Journal of agricultural and food chemistry [J Agric Food Chem] 2009 Jul 22; Vol. 57 (14), pp. 6305-17. - Publication Year :
- 2009
-
Abstract
- The sequential treatment of dewaxed sugarcane bagasse with H(2)O and 1 and 3% NaOH at a solid to liquid ratio of 1:25 (g mL(-1)) at 50 degrees C for 3 h yielded 74.9% of the original hemicelluloses. Each of the hemicellulosic fractions was successively subfractionated by graded precipitation at ethanol concentrations of 15, 30, and 60% (v/v). Chemical composition, physicochemical properties, and structures of eight precipitated hemicellulosic fractions were elucidated by a combination of sugar analysis, nitrobenzene oxidation of bound lignin, molecular determination, Fourier transform infrared (FT-IR), (1)H and (13)C nuclear magnetic spectroscopies, and thermal analysis. The results showed that the sequential treatments and graded precipitations were very effective on the fractionation of hemicelluloses from bagasse. Comparison of these hemicelluloses indicated that the smaller sized and more branched hemicelluloses were extracted by the hot water treatment; they are rich in glucose, probably originating from alpha-glucan and pectic polysaccharides. The larger molecular size and more linear hemicelluloses were dissolved by the alkali treatment; they are rich in xylose, principally resulting from l-arabino-(4-O-methylglucurono)-d-xylans. In addition, noticeable differences in the chemical composition and molecular weights were observed among the graded hemicellulosic subfractions from the water-soluble and alkali-soluble hemicelluloses. The Ara/Xyl ratio increased with the increment of ethanol concentration from 15 to 60%, and the arabinoxylans with higher Ara/Xyl ratios had higher molecular weights. There were no significant differences in the structural features of the precipitated hemicellulosic subfractions, which are mainly constituted of l-arabino-(4-O-methyl-d-glucurono)xylan, whereas the difference may occur in the distribution of branches along the xylan backbone.
- Subjects :
- Chemical Fractionation
Chemical Phenomena
Chemical Precipitation
Hot Temperature
Hydrogen-Ion Concentration
Lignans analysis
Magnetic Resonance Spectroscopy
Polysaccharides analysis
Polysaccharides chemistry
Solubility
Spectroscopy, Fourier Transform Infrared
Water
Ethanol
Polysaccharides isolation & purification
Saccharum chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1520-5118
- Volume :
- 57
- Issue :
- 14
- Database :
- MEDLINE
- Journal :
- Journal of agricultural and food chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 19537731
- Full Text :
- https://doi.org/10.1021/jf900986b