Patent ID: 7932063

Claim:
A method for treating biomass to produce fermentable sugars comprising: a) for a period of time up to about 25 hours, contacting biomass with an aqueous solution comprising ammonia to form a biomass-aqueous ammonia mixture, wherein the ammonia is present at a concentration at least sufficient to maintain alkaline pH of the biomass-aqueous ammonia mixture wherein said ammonia is present at 12 weight percent or less, relative to dry weight of biomass, and further wherein the dry weight of biomass is at a solids concentration of about 15 weight percent or more relative to the weight of the biomass-aqueous ammonia mixture, to produce a pretreated biomass product; and b) contacting the product of step (a) with a saccharification enzyme consortium comprising one or more hemicellulose-hydrolyzing glycosidase, under suitable conditions, to produce fermentable sugars wherein said fermentable sugars provide a carbohydrate source for a biocatalyst for a fermentation process.