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Impact of Temperature, Moisture, and Storage Duration on the Chemical Composition of Switchgrass, Corn Stover, and Sweet Sorghum Bagasse

Athmanathan, Arun, Emery, Isaac R., Kuczek, Thomas, Mosier, Nathan S.
BioEnergy research 2015 v.8 no.2 pp. 843-856
Panicum virgatum, Sorghum (Poaceae), aerobic conditions, bagasse, bioenergy, biomass, chemical composition, corn stover, glucans, hemicellulose, lignin, saccharification, storage time, sugars, sweet sorghum, temperature, xylan
Packaged samples of three bioenergy feedstocks—sweet sorghum, corn stover, and switchgrass—were stored indoors under aerobic conditions to determine the change in chemical composition, track loss of specific chemical constituents, and determine the impact of dry matter loss on saccharification yields with and without pretreatment. Biomass samples were stored under controlled temperature conditions at varying stable biomass moisture contents (10–34 % w/w), temperatures (8–35 °C), and durations up to 16 weeks. Total dry matter losses were measured and sample compositions determined to develop a material balance of storage losses for free sugars, glucan, xylan, and lignin. Maximal losses (24–30 %) were observed for sweet sorghum bagasse at high moisture, while minimal losses (0 %) were observed with switchgrass below the highest tested moisture. Sorghum losses predominantly consisted of free sugars, while switchgrass and stover losses consisted of structural carbohydrates—cellulose and hemicellulose. The mass fraction (% dry weight) of lignin was observed to increase in samples showing dry matter loss, as a result of carbohydrate consumption.