We have discovered a new method to treat biomass with alkali, for example lime. The lime and lignin was sufficiently removed from the treated biomass b> squeezing with a high pressure device to remove alkali and other potential inhibitors of the cellulase enzymes added for saccha.pi.fication. The resulting fibrous material was rapidly solubilzed by cellulases, even at solid loads ranging from 10 to 30% (w/w) without inhibitory effects on the cellulase activity. The lime pretreatment removed lignin effectively and left the cellulose and hemicellulose almost intact. The method yielded a biomass with structure capable of being enzyme solubilzed and fermented readily at a solids loading of 10-30% for a production of ethanol.
 The development of this invention was partially funded by the United States Government under grant number DE-FG36-04G014236 from the United States Department of Energy. The United States Government has certain rights in this invention.