Location: Bioenergy Research Unit
Title: Autohydrolysis of Miscanthus x giganteus for the production of xylooligosaccharides (XOS): Kinetics, characterization and recovery Authors
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 12, 2013
Publication Date: December 22, 2013
Citation: Chen, M.-H., Bowman, M.J., Dien, B.S., Rausch, K.D., Tumbleson, M.E., Singh, V. 2014. Autohydrolysis of Miscanthus x giganteus for the production of xylooligosaccharides (XOS): Kinetics, characterization and recovery. Bioresource Technology. 155:359-365. Interpretive Summary: Production of biofuels from cellulosic biomass promises to expand the supply of renewable transportation fuel in the near future. A scarcity of coproducts is a commercial barrier to producing cellulosic ethanol; and a facility solely producing cellulosic ethanol will likely be unprofitable. Potential candidates for coproduct production include the hemicellulose, which represents the second most abundant component of plant biomass after cellulose. Hemicelluloses can be converted to ethanol or into other products including short soluble carbohydrates called xylooligosaccharides (XOS). There is growing interest in production of XOS based on their beneficial health effects when included in foods because of their functional properties as a soluble fiber and ability to lower cholesterol blood levels. Miscanthus (Miscanthus x giganteus) is a warm season perennial grass that has gained attention as a potential bioenergy crop. In the current research, optima conditions for producing and purifying of xylooligosaccharides (XOS) from Miscanthus were investigated. Reaction conditions were optimized for production of XOS on the basis of yield and the XOS characterized for structural and chemical composition. XOS were recovered by adsorbing onto activated carbon and eluting with a stepwise gradient of aqueous ethanol. The results will be useful to farmers growing warm season bioenergy crops and commercial operators seeking to develop cellulosic biorefineries.
Technical Abstract: The optima conditions of production and purification of xylooligosaccharides (XOS) from Miscanthus x giganteus (MxG) were investigated. Using autohydrolysis, XOS were produced at 160, 180 and 200°C at 60, 20 and 5 min, respectively. XOS yield up to 13.5% (w/w) of initial biomass and 69.2% (w/w) of xylan were achieved. Results from HPAEC-PAD analysis revealed that X1 to X9 sugar oligomers were produced. Higher temperature and longer reaction time resulted in lower product molecular weight. The three optimum conditions had similar degrees of polymerization XOS. Using 10% activated carbon (w/v) with ethanol/water elution recovered 47.9% (w/w) of XOS from pretreated liquid phase. The XOS could be fractionated by degree of polymerization according to ethanol concentration in the ethanol/water elution. Most of the XOS were washed out in 30 and 50% ethanol/water (v/v) fractions. Recoveries of 91.8% xylobiose, 86.9% xylotriose, 66.3% xylotetrose, 56.2% xylopentose and 48.9% xylohexaose were observed in XOS.