Ching-Shuan Lau1, Kris Bunnell1, Edgar C. Clausen2, Greg Thoma2, Jackson O. Lay3, Jennifer Gidden3, and Danielle Julie Carrier1. (1) Department of Biological and Agricultural Engineering, University of Arkansas, Room 203 Engineering Hall, Fayetteville, AR 72701, (2) Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, (3) Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701
In addition to cellulose and lignin, hemicellulose makes up about 30% of biomass. With different compositions in different plant genus, hemicellulose is generally a polymer composed of approximately 200 xylose residues that are linked by β-(1-4) glycosidic bonds to which other sugars, such as arabinose and glucose, are linked. To release hemicellulose from biomass as sugar for fermentation, pretreatment is mandatory.The efficacy of pretreatment is rated according to the production of reactive hemicellulose fraction that can readily undergo fermentation process to form ethanol and the limitation of the pretreated material in inhibiting the growth of the microorganisms during the fermentation. Unfortunately, hemicellulose oligomers do not depolymerize directly into xylose, but form oligomers of various lengths, which can, in turn form furfural, an inhibitor of the fermentation process.Understanding hemicellulose depolymerization is important because it impacts, through the formation of fermentation inhibitors, the overall conversion process by lowering the ethanol production yields. Unfortunately, the study of hemicellulose depolymerization into xylose monomers requires significant amounts of xylose oligomers, which are prohibitively expensive.Birchwood xylan, a type of hemicellulose, is used as the starting material of xylose oligomers production. Birchwood xylan, which contains 97% of sugars in the polysaccharide form of xylose, was hydrolyzed in water at 240 ̊C to produce xylose oligomers. The hydrolyzed fractions were collected during HPLC analysis. The identity of each xylose oligomer fraction was confirmed with the spiking of standard oligomers in HPLC experiments and verified by the molecular weight via MALDI analysis.
