The fed-batch strategy can alleviate the high viscosity problem
caused by high DM concentration, which is essential for generation
of high ethanol amounts. After a prehydrolysis at 50 C in a fedbatch
process (with a cellulase loading of 22.8 FPU/g cellulose),
the final dry matter in the experiments could be increased up to
25%. Ethanol concentrations of up to 84.7 g/L could be produced
from a DM content of 25% by adding fresh substrate every 4 h during
the first 24 h of SSF. To our knowledge, it is the highest ethanol
concentration yet reported and exceeds the technical and economic
limits of industrial-scale alcohol distillation