Low moisture content of chopped sorghum is advantageous since the chance of contamination of fermentation
medium is reduced. However, there is a limit of moisture
content below which yeast cells may not be functional to
produce ethanol. As the moisture level decreased from 75% to
60%, the ethanol yield declined sharply from 7.5 to 2.2 g ethanol
per 100 g fresh stalks. High moisture level made the stalks stick
together during the SSF, which can hinder the heat transfer and
exchange of carbon dioxide between the air and the solid
surface, too. At 75–80% moisture level, the highest ethanol yield
of 7.5 g ethanol per 100 g fresh stalks was obtained. Lower
moisture content it is, less energy is needed for product
recovery. So, moisture level of 75% was applied below