Fractional and physico-chemical characterization of hemicelluloses from ultrasonic irradiated sugarcane bagasse

• Published in: Carbohydrate research 2004-01, Vol.339 (2), p.291-300
• Main Authors: Sun, Jing-Xia, Sun, RunCang, Sun, Xiao-Feng, Su, YinQuan
• Format: Article
• Language: English
• Subjects: Cellulose - chemistry; Cellulose - radiation effects; Chemical Fractionation; Extraction; Hemicelluloses; Lignin - chemistry; Lignin - isolation & purification; Magnetic Resonance Spectroscopy; Molecular Weight; Polysaccharides - chemistry; Polysaccharides - isolation & purification; Saccharum - chemistry; Saccharum - radiation effects; Spectroscopy, Fourier Transform Infrared; Sugarcane bagasse; Temperature; Ultrasonics; Ultrasound
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2003.10.027

Eight hemicellulose preparations were isolated from bagasse using ultrasonic treatment and sequential extractions with alkali and alkaline peroxide and their structures studied by 1H and 13C NMR spectroscopy. The present study was undertaken to investigate the extractability of the hemicelluloses from bagasse obtained by ultrasound-assisted extraction methods. The results showed that the ultrasonic treatment and sequential extractions with alkali and alkaline peroxide under the conditions given led to a release of over 90% of the original hemicelluloses and lignin. This fact as well as the sugar composition and structural features of the isolated seven hemicellulosic fractions indicated that ultrasonication attacked the integrity of cell walls, cleaved the ether linkages between lignin and hemicelluloses, and increased accessibility and extractability of the hemicelluloses. Increasing alkali concentration from 0.5 to 2 M and alkaline peroxide percentage from 0.5% to 3.0% resulted in degradation of hemicellulosic backbone as shown by a decrease in their molecular weights from 43,580 to 14,470 and 30,180 to 18,130 g mol −1, respectively. However, there were no significant differences in the structural features of the seven sequential alkali- or alkaline peroxide-soluble hemicellulosic fractions, which are composed mainly of l-arabino-(4- O-methyl- d-glucurono)- d-xylans. Ferulic and p-coumaric acids were found to be chemically linked with hemicelluloses.