Tuesday, May 1, 2012: 10:30 AM
Waterbury Ballroom, 2nd fl (Sheraton New Orleans)
Several studies are directed to the conversion and utilization of sugarcane feedstock aimed at second-generation ethanol production. A lot of work has been done to chemically characterize the material but there is a lack of understanding about changes in the cell wall ultrastructure during processing. For this work defined areas of the sugarcane stalk were characterized with different methods before and after particular processing steps. Bottom, middle and top portions of the sucarcane stalk were submitted to a hydrothermal treatment (180oC, 20 min) followed by alkaline delignification (NaOH 1% (w/v), 98oC, 1 h). 600µm thick transverse sections of un-modified and treated samples were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Raman microscopy. 550µm thick longitudinal sections were evaluated using Small Angle X-Ray Scattering (SAXS). The cell wall thickness of dried samples was ca. 50% smaller compared to the fully hydrated sample (ESEM). SAXS shows the orientation of cellulose microfibrils in parenchymatic cell walls are perpendicular to the growth axis whilst the fibrils are oriented parallel in vascular bundles. Raman results are inconclusive however information on the lignin content and cellulose orientation among the cell walls was obtained. Significant differences were found within samples from different stalk portions as well as after chemical treatments. [The authors acknowledgements the FAPESP, DAAD, CAPES and CNPq for support]