Supercritical ammonia treatment of lignocellulosic materials

DETAILED DESCRIPTION OF THE INVENTION As used throughout the specification, "bioavailability" refers to the relative ability of a particular material to be hydrolyzed by cellulase and related enzymes, or, in the alternative, to the relative utility of a particular material as a carbohydrate source in microbial fermentation.
Thus, materials with increased bioavailability, as that term is employed herein, are more readily hydrolyzed by cellulases, or more readily degraded and metabolized by microbial activity.
"Polysaccharide," as employed throughout the specification, refers to polymeric constituents of lignocellulosic materials which comprise repeating monosaccharide units.
Exemplary polysaccharides include cellulose in the various forms found in lignocellulosic materials, and hemicelluloses such as xylans, mannans, and galactans.
As used herein, "lignocellulosic materials" refers generally to plant tissue, particularly structural plant tissue comprising complex associations of polysaccharides and lignin.
Exemplary materials within this definition include agricultural waste materials and by-products, hardwoods and softwoods.
Suitable agricultural waste materials and by-products to be treated by the process of the present invention can be derived from any source.
Examples of such materials include cornstalks, corn cobs, wheat, oat, and barley straw, and bagasse.
These materials are generally considered poor fodder for animals or poor substrates for rapid microbial fermentation, due the relative indigestibility of cellulose and related polysaccharides, which are the principal components of these materials.
However, following treatment by the process of the present invention, more than 90 percent of the available polysaccharides in the form of cellulose and hemicelluloses can be converted to monosaccharides by cellulases.
Suitable woody materials can likewise be derived from any source.
However, hardwoods or deciduous woods are generally more effectively treated by the process of the present invention than softwoods, or coniferous woods