Influence of hemicellulose and lignin on the effect of drying of cellulose and the subsequent enzymatic hydrolysis

Abstract

Transporting water contained in lignocellulosic biomass is both costly and impractical. Thus, the inevitable increase in the utilization of biomass derived products such as hygroscopic nanocellulose and dissolving pulp cellulose prior to downstream chemical/enzymatic processing will necessitate a greater understanding of the potential drying induced impacts on the reactivity/accessibility of cellulose. To assess the effects of hemicellulose and lignin on the drying behavior and enzymatic hydrolysis of cellulose, corn stover was subjected to steam pretreatment, bleaching, and LiBr·3H₂O treatment to produce model substrates rich in holocellulose, cellulose-lignin, pure cellulose and the original composition. The model substrates were freeze-dried, air-dried, and oven-dried, and were subjected to Simons’ staining (both wet and dried samples) and N₂ adsorption analysis (dried samples) to assess cellulose accessibility and surface area. Drying-induced hornification reduced cellulose accessibility, with freeze-drying preserving the structure more effectively than oven or air drying. The presence of hemicellulose and lignin influenced drying-induced hornification by significantly increasing cellulose accessibility. Hemicellulose removal was as effective as lignin removal in enhancing enzymatic hydrolysis at low enzyme loading, but its presence played a key role in mitigating drying effects. Additionally, cellulose properties, such as the degree of polymerization, affected drying responses, as seen in the reduction of hydrolysis yield in endoglucanase-treated dissolving pulp.