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Simultaneous saccharification and fermentation of steam-pretreated barley straw at low enzyme loadings and low yeast concentration

Linde, Marie LU ; Galbe, Mats LU and Zacchi, Guido LU (2007) In Enzyme and Microbial Technology 40(5). p.1100-1107
Abstract
The maximum concentration of water-insoluble solids (WIS) in simultaneous saccharification and fermentation (SSF) is restricted due to inhibition of the enzymes and the yeast, as well as mass transport problems caused by the viscosity of the pretreated material. However, the higher the concentration of WIS during SSF the less energy is needed in the subsequent distillation and evaporation steps. In this study, SSF was performed on barley straw sprayed with H2SO4 and steam pretreated at conditions yielding a highly digestible material, aiming to increase the WIS concentration and decrease the enzyme loading and the yeast concentration in SSF, in order to reduce the production cost. Three concentrations of WIS (5, 7.5 and 10%), and three... (More)
The maximum concentration of water-insoluble solids (WIS) in simultaneous saccharification and fermentation (SSF) is restricted due to inhibition of the enzymes and the yeast, as well as mass transport problems caused by the viscosity of the pretreated material. However, the higher the concentration of WIS during SSF the less energy is needed in the subsequent distillation and evaporation steps. In this study, SSF was performed on barley straw sprayed with H2SO4 and steam pretreated at conditions yielding a highly digestible material, aiming to increase the WIS concentration and decrease the enzyme loading and the yeast concentration in SSF, in order to reduce the production cost. Three concentrations of WIS (5, 7.5 and 10%), and three enzyme loadings (5, 10 and 20 FPU/g cellulose) of Celluclast 1.5 L complemented with Novozym 188 were investigated in terms of ethanol yield. Ordinary cultivated Baker's yeast and Baker's yeast cultivated on barley straw hydrolyzate were also evaluated in terms of ethanol yield. The highest ethanol yield, 82% of the theoretical based on the glucose content in barley straw, was obtained after SSF with 5% WIS at an enzyme loading of 20 FPU/g cellulose together with 5 g/L ordinary cultivated yeast. Increased WIS concentration and decreased enzyme loading decreased the ethanol yield. However, by cultivating the yeast in hydrolyzate from pretreated barley straw the WIS concentration in SSF could be increased from 5% to 7.5% and the yeast concentration could be reduced from 5 to 2 g/L, while still attaining a yield of approximately 80%. (c) 2006 Elsevier Inc. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
barley straw, SSF, fermentation, simultaneous saccharification and, ethanol, steam pretreatment
in
Enzyme and Microbial Technology
volume
40
issue
5
pages
1100 - 1107
publisher
Elsevier
external identifiers
  • wos:000245519000016
  • scopus:33847618375
ISSN
0141-0229
DOI
10.1016/j.enzmictec.2006.08.014
language
English
LU publication?
yes
id
f0798124-9e37-4f23-91dd-58fc1cb5a8dc (old id 667886)
date added to LUP
2007-12-14 15:18:51
date last changed
2017-09-17 04:49:21
@article{f0798124-9e37-4f23-91dd-58fc1cb5a8dc,
  abstract     = {The maximum concentration of water-insoluble solids (WIS) in simultaneous saccharification and fermentation (SSF) is restricted due to inhibition of the enzymes and the yeast, as well as mass transport problems caused by the viscosity of the pretreated material. However, the higher the concentration of WIS during SSF the less energy is needed in the subsequent distillation and evaporation steps. In this study, SSF was performed on barley straw sprayed with H2SO4 and steam pretreated at conditions yielding a highly digestible material, aiming to increase the WIS concentration and decrease the enzyme loading and the yeast concentration in SSF, in order to reduce the production cost. Three concentrations of WIS (5, 7.5 and 10%), and three enzyme loadings (5, 10 and 20 FPU/g cellulose) of Celluclast 1.5 L complemented with Novozym 188 were investigated in terms of ethanol yield. Ordinary cultivated Baker's yeast and Baker's yeast cultivated on barley straw hydrolyzate were also evaluated in terms of ethanol yield. The highest ethanol yield, 82% of the theoretical based on the glucose content in barley straw, was obtained after SSF with 5% WIS at an enzyme loading of 20 FPU/g cellulose together with 5 g/L ordinary cultivated yeast. Increased WIS concentration and decreased enzyme loading decreased the ethanol yield. However, by cultivating the yeast in hydrolyzate from pretreated barley straw the WIS concentration in SSF could be increased from 5% to 7.5% and the yeast concentration could be reduced from 5 to 2 g/L, while still attaining a yield of approximately 80%. (c) 2006 Elsevier Inc. All rights reserved.},
  author       = {Linde, Marie and Galbe, Mats and Zacchi, Guido},
  issn         = {0141-0229},
  keyword      = {barley straw,SSF,fermentation,simultaneous saccharification and,ethanol,steam pretreatment},
  language     = {eng},
  number       = {5},
  pages        = {1100--1107},
  publisher    = {Elsevier},
  series       = {Enzyme and Microbial Technology},
  title        = {Simultaneous saccharification and fermentation of steam-pretreated barley straw at low enzyme loadings and low yeast concentration},
  url          = {http://dx.doi.org/10.1016/j.enzmictec.2006.08.014},
  volume       = {40},
  year         = {2007},
}