Solid state fermentation of chopped sweet sorghum particles to produce ethanol was
studied statically using thermotolerant yeast. The influence of various process parameters,
such as yeast cell concentration, particle size and moisture content, on the ethanol yield
was investigated. Optimal values of these parameters were 4× 106 cells/g raw sorghum,
Dp = 1.5 mm and 75%, respectively. Addition of reducing agent H2SO3 into the fermentation
medium provided anaerobic condition, and obtained the maximum ethanol yield of 7.9 g
ethanol per 100 g fresh stalks or 0.46 g ethanol/g total sugar, which was 91% of the theoretic
yield.