ABSTRACT
The most important are extractives that may comprise up to 10% of the biomass material, bark that makes up 10 to 15% of woody plant biomass, and nonstructural carbohydrates, which in some specialized cases such as cereal grains, constitute almost the entire seed. If the composition of biomass were as varied as its morphology, it would be necessary to deal with many thousands of compounds in attempting to convert biomass to chemicals. The cell wall components are intimately associated in their native state, and, as a consequence, their properties and response to processing are influenced by the close proximity of the other components as well as possible chemical combination with them. Plant cell walls contain skeletal polysaccharides, hemicelluloses, polyuronides, lignin, and proteins. For conversion into chemicals, the important features of the structure of cellulose are that it is a linear polymer of glucose with a highly ordered crystalline structure that limits the accessibility of reagents and enzymes.
