Youngmi Kim, Laboratory of Renewable Resources Engineering (LORRE), Purdue University, Potter Engineering Center, 500 Central Drive, West Lafayette, IN 47907-2022, Nathan S. Mosier, Agricultural and Biological Engineering & Laboratory of Renewable Resources Engineering (LORRE), Purdue University, Potter Engineering Center, 500 Central Drive, West Lafayette, IN 47907-2022, and Michael R. Ladisch, Laboratory of Renewable Resources Engineering Department, Purdue University, Potter Engineering Center, 500 Central Drive, West Lafayette, IN 47907-2022.
The conversion of switchgrass to fermentable sugars and ethanol provides a cellulosic feedstock for production of fuel ethanol which may be grown on lands not suitable for food agriculture. Switchgrass itself consists of 33% cellulose, 25% hemicelluloses, 18% lignin, and 24% other. If switchgrass is processed without pretreatment, the maximal conversion achieved at an enzyme loading of 15 FPU/g glucan (5 FPU/g biomass) is less than 5%. When the switchgrass is pretreated in liquid hot water, the conversion increases by 25-fold, resulting in 80% glucose yield. The utilization of liquid hot water followed by enzyme hydrolysis and fermentation is described in this paper. The levels of enzyme loading and inhibition effects are briefly discussed as part of the overall CAFI research project.