Volume 46, No. 03, Month MAY, Year 2019, Pages 481 - 494
Ethanol production from sweet sorghum juice under very high gravity fermentation by saccharomyces cerevisiae : aeration strategy and its effect on yeast intracellular composition
Pattana Laopaiboon, Naulchan Khongsay, Niphaphat Phukoetphim and Lakkana Laopaiboon
A new technique of aeration during ethanol fermentation from sweet sorghum juice
under very high gravity (VHG) condition was investigated to improve ethanol production
efficiency of Saccharomyces cerevisiae NP 01. Response surface methodology (RSM) analysis
showed that the optimal aeration conditions for ethanol production were an aeration rate,
aeration time and agitation rate at 2.50 vvm, 4.44 h and 197 rpm, respectively. When the
verification experiment under the optimal conditions was performed in a 5-L bioreactor,
ethanol concentration (P), productivity (Qp) and ethanol yield (Yp/s) were 131.75 0.76 g l-1,
2.53 0.01 g l-1 h-1 and 0.00 0.76, respectively. Under an unaerated condition (control
treatment), the P, Qp and Yp/s values were 120.72 1.37 g l-1, 2.24 0.03 g l-1h-1 and 0.50 0.00,
respectively. Additionally, total fatty acids (TFAs) and ergosterol concentrations in the
yeast cells at the fermentation time under the optimal aeration conditions were 2637.14
64.39 and 282.37 18.46 g gDCW
-1, respectively. These values under the control
conditions were 1587.05 25.33 and 201.09 24.33 g gDCW
-1, respectively. The results
clearly indicated that optimal aeration can improve ethanol production efficiency of
yeast cells, which might be related to an increase in their intracellular components, i.e.,
TFAs and ergosterol.