The presently disclosed subject matter related to methods of converting lignocellulosic materials to alcohol that include increasing the fiber consistency of enzymatic hydrolysis mixtures. More particularly, the methods involve contacting lignocellulosic biomass with an enzyme composition for a period of time, and then thickening the mixture and further hydrolyzing the thickened mixture. The thickening can be performed by filtration, optionally reusing the filtrate and/or any enzymes contained therein during the lignocellulose conversion process to increase the efficiency of the process. Hydrolysis of the thickened mixture provides a fermentable sugar mixture having a higher concentration of sugar than fermentable sugar mixtures provided from less concentrated biomass/enzyme mixtures. Compositions comprising alcohol prepared according to the presently disclosed methods are also provided.