Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 31, 2009
Publication Date: October 2, 2009
Citation: Saha, B.C., Cotta, M.A. 2009. Fuel Ethanol Production from Barley Straw. Proceedings of the United States-Japan Natural Resources Food and Agriculture Panel. p. 139-142. Technical Abstract: Barley straw used in this study contained 34.1±0.6% cellulose, 22.6±0.4% hemicelluloses, and 13.3±0.2% lignin (moisture, 6.5±0.0%). Several pretreatments (dilute acid, lime, and alkaline peroxide) and enzymatic saccharification procedures were evaluated for the conversion of barley straw to monomeric sugars. The maximum release of sugars (glucose, 395±0 mg; xylose, 176±0 mg; arabinose, 32±0 mg; total sugars, 604±0 mg; 94% yield) from barley straw (10%, w/v) was obtained by alkaline peroxide (2.5% H2O2, pH 11.5) pretreatment (35 deg C, 24 h) and enzymatic saccharification (45 deg C, pH 5.0, 120 h) after diluting 2 times prior to adding a cocktail of 3 commercial enzyme (cellulase, beta-glucosidase, and hemicellulase) preparations each at the dose level of 0.15 ml/g of straw. Dilute acid and lime pretreatments followed by enzymatic saccharification generated 566±8 mg (89% yield) and 582±38 mg (92% yield) sugars, respectively, per g of barley straw. The yield of ethanol from the dilute acid pretreated and enzymatically saccharified barley straw hydrolyzate (23.7±0.1 g/L) was 11.4±0.1 g/L (0.48 g/g available sugars, 0.26 g/g straw) by a mixed sugar utilizing recombinant Escherichia coli strain FBR5 in 17 h. The ethanol yields were 11.4±0.1 and 11.9±0.6 g/L from 24.4±0.4 and 26.2±0.1 g sugars/L obtained from lime and alkaline peroxide pretreated barley straw, respectively. No inhibition of fermentation occurred by any of the three pretreatments under the conditions used.