In order to establish the baseline quantities of key fermentable sugars, switchgrass (Panicum virgatum L., var. Alamo) stems and leaves were pretreated with dilute acid, and the release of sugars was compared to that reported in the U.S. DOE biomass feedstock composition and property database. Switchgrass was planted in the spring of 2008 and harvested in the spring of 2009. The feedstock was separated into leaves and stems and ground to particle sizes of 0.34 and 0.37 mm, respectively. Dilute acid pretreatment of the material (130°C in 0.98% H 2SO 4 for 25 min) yielded xylose recoveries of 76% and 61% for leaves and stems, respectively. Recoveries were calculated by dividing the recovered sugar by the values reported in the DOE feedstock database. Coupling a 2 h 85°C hot water presoaking step to the 25 min 130°C in 0.98% H 2SO 4 pretreatment increased the xylose recovery by 23% and 5% for leaves and stems, respectively. These results demonstrate that a presoaking step increases the sugar release without escalating the severity of the pretreatment. Moreover, the 85°C presoaking water contained the flavonoid quercetin, which is a documented antioxidant. The presoaking water from leaves and stems displayed yields of 0.14 and 0.12 mg of quercetin per g of dry switchgrass, respectively. Thus, the presoaking step not only increases monosacchride recovery, but provides a slipstream that could be processed into a value-added revenue-generating stream for the biorefinery.
|Number of pages||5|
|Journal||Transactions of the ASABE|
|State||Published - Sep 2011|
- Dilute acid pretreatment