초록
<P><B>Abstract</B></P> <P>Ethanol production from sweet sorghum bagasse (SSB) is reported. A two-step pretreatment with hydrogen peroxide followed by NaOH at 121 °C for 20 min, was used prior to enzymatic treatment. Enzymatic treatment was carried out using a commercial cellulase. Enzymatic hydrolysis for 72 h resulted in a hydrolysate containing xylose (5.1 g L<SUP>−1</SUP>), glucose (75.3 g L<SUP>−1</SUP>) and cellobiose (1.4 g L<SUP>−1</SUP>). This hydrolysate was used to produce ethanol by a 72-h fermentation with the yeast <I>Saccharomyces cerevisiae</I> TISTR 5606 at 30 °C. This separate hydrolysis and fermentation (SHF) method was compared with a simultaneous saccharification and fermentation (SSF) method. The SSF process used the pretreated SSB and was carried out in two different ways: (1) In the first method, the enzyme, the substrate and the yeast inoculum were mixed and SSF fermentation took place at 37 °C for 72-h, to produce a final ethanol concentration of 22.3 g L<SUP>−1</SUP>; (2) in the second method, termed the ‘delayed simultaneous-saccharification fermentation’ or DSSF, the pretreated SSB was enzymatically hydrolyzed at 50 °C for 6-h, cooled to 37 °C, and then inoculated with the yeast to commence a 66-h fermentation. This gave a final ethanol concentration of 28.3 g L<SUP>−1</SUP>. The ethanol productivity was 0.31 g L<SUP>−1</SUP> h<SUP>−1</SUP> for the SHF and SSF processes, but the DSSF had a ∼26% higher productivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Processes for bioethanol from sweet sorghum bagasse (SSB) are evaluated. </LI> <LI> SSB is biochemically characterized in detail before and after pretreatment. </LI> <LI> Sequential and simultaneous options for hydrolysis–fermentation are compared. </LI> <LI> Simultaneous hydrolysis–delayed fermentation outdoes the other options. </LI> <LI> The best process option had ∼26% higher productivity than the other options. </LI> </UL> </P>