Understanding the biochemical changes at molecular level during biomass pretreatment: a comprehensive analysis

Abstract

To successfully convert lignocellulosic biomass into value-added products, it is necessary to overcome its structures’ resistance to enzymatic digestion. Pretreatment of lignocellulosic biomass is an inevitable process loosening the carbohydrate-lignin network, thus improving the digestibility/enzymatic saccharification into second-generation sugars. Several pretreatment methods exist; however, steam explosion with or without catalyst, dilute acid hydrolysis, alkaline pretreatment, hydrothermal, and organosolv pretreatment have been studied in detail. Although several pretreatment techniques have been established, the feasibility of these techniques on a large scale remains a major bottleneck in the biorefinery. In this sense, emerging technologies such as supercritical fluids, ionic liquids, hydrodynamic cavitation, and nanobiotechnology have shown encouraging results in terms of process feasibility. This paper discusses the key pretreatment techniques, their advantages, and disadvantages. Additionally, the chemical and physical changes that occurred due to different pretreatments on the biomass at a molecular level are discussed and compared using Microsoft Power BI. Finally, the perspective of emerging technologies is explored, and future trends in biomass pretreatment are provided.