Disclosed are methods and systems for a first stage of fractionating a lignocellulosic material or lignocellulosic-containing biomass to extract phytochemicals and low molecular weight lignins and lignans, collectively identified as extractives, by treating lignocellulosic material or biomass with an alkali in an exemplary alcohol/water co-solvent system. The extractives are species specific and can later be separated and isolated individually. The system has the added advantage that it renders the residual polymeric biomass, sometimes referred to as bagasse, as an enhanced digestibility animal feed or more accessible for enzymatic or chemical modification. The extractives separated in the methods of the invention are in a form closer to their native state than any form that can be obtained from other biomass pretreatment processes.
