New research of Institute of Process Engineering, Chinese Academy of Sciences (IPE) showed an economic and effective method for ethanol production. Under optimal conditions, ethanol was produced by solid state fermentation (SSF) of sweet sorghum stalk.

It has been reported that submerged fermentation (SmF) or immobilized cell fermentation are common methods for fuel ethanol production. SSF has so many advantages such as high efficiency, low energy consumption and simple fermentation system that it is considered to be a green method to produce ethanol.

Issatchenkia orientalis IPE 100, the thermotolerant yeast was used in the experiments. Researchers discussed the effect of operation parameters on SSF by I. orientalis IPE 100. The maximum ethanol yield achieved in the SSF of sweet sorghum stalk at 42oC, 75%(w/w) water content, 2mm particle size and 3% (w/w) inoculation rate in 250-mL conical flask. The influence of substrate depth and operation temperature on SSF in 10-L reactor was demonstrated. The deep-bed SSF increased the loading efficiency of the fermented substrate and high ethanol yield obtained.

More results of the research were shown in the paper titled “Deep-bed solid fermentation of sweet sorghum stalk to ethanol by thermotolerant Issatchenkia orientalis IPE 100” published on Bioresource Technology.