Abstract: A biorefining process used to convert lignocellulosic biomass into ethanol via a fermentation pathway. In a first pretreatment process step, the biomass is mixed with an aqueous wash solution to remove soluble carbohydrates from the biomass structure. Next, the solid fraction is separated from a liquid fraction. In a second pretreatment process, the solid fraction is pre-treated to make the fiber bundles and complex polysaccharides more amenable to enzymatic hydrolysis. Following the second pretreatment process, the pre-treated biomass is subjected to one or more enzymes in a hydrolysis process. The liquid fraction isolated from the first pretreatment process is diverted past the second pretreatment process and is recombined with the solid fraction in the hydrolysis process. The enzyme cocktail in the hydrolysis process breaks down the alpha- and hemicellulose polymers into fermentable sugars.