title: Evaluation of ammonia fibre expansion (AFEX) pretreatment for enzymatic hydrolysis of switchgrass harvested in different seasons and locations.
abstract: BACKGROUND
  When producing biofuels from dedicated feedstock, agronomic factors such as harvest time and location can impact the downstream production. Thus, this paper studies the effectiveness of ammonia fibre expansion (AFEX) pretreatment on two harvest times (July and October) and ecotypes/locations (Cave-in-Rock (CIR) harvested in Michigan and Alamo harvested in Alabama) for switchgrass (Panicum virgatum).
  
  
  RESULTS
  Both harvest date and ecotype/location determine the pretreatment conditions that produce maximum sugar yields. There was a high degree of correlation between glucose and xylose released regardless of the harvest, pretreatment conditions, or enzyme formulation. Enzyme formulation that produced maximum sugar yields was the same across all harvests except for the CIR October harvest. The least mature sample, the July harvest of CIR switchgrass, released the most sugars (520 g/kg biomass) during enzymatic hydrolysis while requiring the least severe pretreatment conditions. In contrast, the most mature harvest released the least amount of sugars (410 g/kg biomass). All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.
  
  
  CONCLUSIONS
  Each harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars. Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.
authors.affiliation: Biomass Conversion Research Laboratory, Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Bals
authors.forename: Chad
authors.initials: C
authors.lastname: Rogers
authors.forename: Mingjie
authors.initials: M
authors.lastname: Jin
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Balan
authors.forename: Bruce
authors.initials: B
authors.lastname: Dale