| Summary: | ABSTRACT This study aimed to determine the best dilute acid hydrolysis condition for the hemicellulosic fraction of sweet sorghum bagasse for ethanol production by Scheffersomyces stipitis. The experiment followed a 23 factorial design with four central points, and had as variables: sulfuric acid concentration, temperature and hydrolysis time. Sorghum bagasse presented the following chemical composition: 24.77% of lignin, 31.28% of hemicellulose and 34.80% of cellulose. The hydrolysis that resulted in the highest sugars concentration (14.22 g/L of xylose and 2.42 g/L glucose) was 1.75% H2SO4, 121 ºC and 40 minutes. This same condition provided low concentrations of toxic compounds (1.34 g/L of acetic acid, 0.90 g/L of phenol; 124.54 mg/L of hydroxymethylfurfural (HMF) and 978 mg/L of furfural). The fermentation of the hemicellulose-derived sugars by S. stiptis resulted in 22 g/L of ethanol, YP/S 0.40 g/g and Qp 0.34 g/L.h.
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