The successful conversion of lignocellulose into value-added products depends on overcoming the recalcitrance of its structure towards enzymatic digestion. The highly crosslinked structure of lignin, crystallinity of cellulose, and low digestibility of hemicellulose create the recalcitrance. Many studies have proved that an appropriate pretreatment method could enhance the digestibility of lignocellulosic biomass by weakening the strong network of its chemical bonds among the cellulose, hemicellulose, and lignin.
