Particle size reduction did not cause a significant improvement in YOE values when DSA pretreated solids were fermented. However,the use of small size particles derived from no-acid assays (LHW and E&LHW) produced a strong positive effect in bio-fuel production. Of note was the increase of YOE (85.7%) when small size particles derived from LHW pretreatment were subjected to SSF. Therefore, the use of organic solvent in pretreatments could be replaced by a previous grinding stage because the overall ethanol yield achieved with finer solids from LHW experiment (13.0 kg/100 kg OS) was higher than that obtained using E&LHW pretreated solids (10.6e12.7 kg/100 kg OS).