**Acknowledgements**

The authors would like to thank the University of Arkansas, Division of Agriculture, and the Department of Biological and Agricultural Engineering, for financial assistance. The authors would also like to acknowledge Department of Energy award 08GO88035 for pretreatment equipment and support; CRREES National Research Initiative award no. 2008-01499 for the HPLC instrument, and the Plant Powered Production (P3) Center through an NSF RII Arkansas ASSET Initiative (AR EPSCoR) for the support of undergraduate and graduate student stipend and equipment.
