Sunday, May 3, 2009
3-44
Identification and Quantitation of Water Extractives in Sorghum
Richard S. Sevcik, Zachary Hardie, Richard Mowery, and C. Kevin Chambliss. Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348
Sorghum has gained interest as a biomass feed stock with its high crop yields and drought tolerance. Its value as a feedstock for bioprocessing is inherently dependent upon detailed knowledge of its chemical composition. Currently accepted analytical procedures for compositional analysis of biomass enable near-quantitative mass closure on a dry-weight basis. However, total water- and/or ethanol-soluble materials are quantified gravimetrically and identified only as ‘extractives’. Reported compositional analyses of water-soluble materials in corn stover and switchgrass have shown that fermentable sugars (primarily glucose, fructose, and sucrose) represent as much as ~26% and ~27% of the dry weight of extractives respectively (~4% and ~7% of the total dry weight of each feed stock respectively). Preliminary data indicates that water-soluble sugars may represent an even larger fraction of extractives in sorghum extracts. The analytical techniques developed to determine the composition of water-soluble materials in corn stover and switchgrass are being applied to assess the composition of water-soluble materials in sorghum samples. Sorghum results will be compared with previous analyses of corn stover and switchgrass extracts and presented in the context of their potential impact on biomass processing, feedstock storage, and future analyses of feedstock composition.