Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Elucidating the physicochemical properties of bioenergy crops will help in their utilization for fuels and chemical. Hemicellulose, the second most abundant polysaccharide in biomass, not only presents a barrier for enzymatic access to cellulose, but also contains sugars that can be utilized as substrates for fermentation. Understanding the physicochemical properties of hemicellulose could help to maximize hydrolysis of the material while minimizing production of inhibitory byproducts during pretreatment of biomass for conversion to fuels and chemicals. This work focused on characterizing alkali-extracted hemicelluloses from Panicum virgatum, L. (switchgrass), cultivar Alamo, harvested at mid-growing season (July) and weathered post-frost (February). The alkali-extracted hemicelluloses were analyzed for monosaccharide constituents, monomeric linkages, and size using acid hydrolysis, methylation analyses, and dynamic light scattering, respectively. The results revealed that the July hemicellulose composition by mass was 13% glucose, 68% xylose, and 19% arabinose, and the February hemicellulose composition by mass was 5% glucose, 80% xylose, and 15% arabinose. Linkage analyses and dynamic light scattering revealed different degrees of branching and overall size between the hemicelluloses. These results suggest that the physicochemical properties of switchgrass hemicelluloses do change with plant maturity, and these changes should be accounted for when selecting pretreatment conditions so that selective production of monosaccharides and byproducts can be achieved.