title: Extraction of proteins from switchgrass using aqueous ammonia within an integrated biorefinery.
abstract: Switchgrass (Panicum vergatum) is a potential feedstock for future cellulosic biorefineries. Such a feedstock may also provide protein, most likely for use as an animal feed. In this paper, we present a potential scheme for integrating fiber processing with extractions to obtain both sugar and protein products from switchgrass pretreated using Ammonia Fiber Expansion (AFEX). Solutions of 3% aqueous ammonia at pH 10.5 provided optimal extraction of proteins. Addition of the nonionic surfactant Tween-80 improved protein recovery for AFEX-treated materials. It was determined that an extraction following AFEX solubilized approximately 40% of the protein, while a subsequent hydrolysis solubilized much of the remaining protein while producing 325 g sugar per kg biomass. The remaining insoluble residue contained very little protein or ash, making it ideal for heat and power production. In contrast, an extraction following hydrolysis solubilized only 68% of the original protein in the biomass, while obtaining slightly higher sugar yields.
authors.affiliation: Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48824-1226, USA. balsbrya@msu.edu
authors.forename: Bryan
authors.initials: B
authors.lastname: Bals
authors.forename: Laura
authors.initials: L
authors.lastname: Teachworth
authors.forename: Bruce
authors.initials: B
authors.lastname: Dale
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Balan
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000641:Ammonia / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008897:Panicum / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D010936:Plant Extracts; D010940:Plant Proteins; D000641:Ammonia