Detrimental effect of increasing sugar concentrations on ethanol production from maize or decorticated sorghum mashes fermented with Saccharomyces cerevisiae or Zymomonas mobilis Biofuels and environmental biotechnology

摘要

The efficiency of ethanol fermentation, as affected by grain source (maize and decorticated red sorghum), total sugar concentration (13 or 20° Plato) and type of microorganism (Saccharomyces cerevisiae or Zymomonas mobilis) was studied. Maize mashes yielded 0.32 l ethanol kg−1 ground grain whereas mashes prepared with decorticated red sorghum produced 0.28 l ethanol kg−1. Both microorganisms yielded similar amounts of ethanol. However, high-gravity mashes (20° Plato) yielded lower amounts of ethanol compared to counterparts adjusted to 13° Plato (0.28 vs. 0.22 l ethanol kg−1 ground grains). In decorticated sorghum mashes adjusted to 20° P, Z. mobilis produced 40 ml kg−1 more ethanol compared to S. cerevisiae. In addition, Z. mobilis had a lower dependency on nitrogenous compounds.