Chemical aspects of the composite structure of wood and its recalcitrance to enzymatic hydrolysis

Abstract

Woody biomass as a renewable resource for chemicals, materials, and energy has garnered significant attention to replace fossil-carbon sources. However, in carbohydrate-based biorefineries, the recalcitrance of wood warrants a pretreatment prior to further processing by enzymatic hydrolysis (EH) and fermentation. Various processes or a combination thereof, including but not limited to, low pH (mild and strong acid pretreatments), neutral pH (autohydrolysis includes hydrothermal and steam explosion pretreatments), high pH (mild and strong alkali pretreatments), organic solvents, ionic liquids, deep-eutectic solvents, biological methods, electron beam and microwave irradiation, and mechanical methods (ultrasound and grinding), are currently under investigation as pretreatment methods to facilitate the subsequent EH. Wood is a natural composite, comprised of structural constituents: cellulose, lignin, and hemicelluloses; and minor, nonstructural compounds: extractives. The recalcitrance of wood is a multifaceted phenomenon inextricably linked to the structure of individual structural polymers, as well as their close interactions. In this chapter, we describe the formation of the wood matrix, the individual constituents (chemical composition), and their contribution to the recalcitrance of wood. In-depth understanding of these concepts is required to pave the way to better tailor processes for the complete valorization of wood as a sustainable feedstock.

Citation

Dongre, Prajakta; Nagardeolekar, Aditi; Corbett, Derek; Bujanovic, Biljana M. 2023. Chemical aspects of the composite structure of wood and its recalcitrance to enzymatic hydrolysis. In: Kumar, D.; Kumar, S.; Rajendran, K., eds., Sustainable Biorefining of Woody Biomass to Biofuels and Biochemicals. Cambridge, MA: Elsevier: 1-41. https://doi.org/10.1016/B978-0-323-91187-0.00012-6.