Chemical variation in cell wall of sugar beet pulp caused by aqueous ammonia pretreatment influence enzymatic digestibility of cellulose

Abstract Sugar beet pulp (SBP) is considered to be an important feedstock for the fuel ethanol production. The aim of this study is to investigate the relationship between chemical variation in cell wall caused by aqueous ammonia pretreatment and the enzymatic digestibility of cellulose through imaging techniques coupled with enzymatic hydrolysis kinetics analysis. The results revealed that the partly decreased and redistributed lignin could weaken interactions between lignin and cellulose, expose more hydroxyl groups on cell wall, and lead to more absorbed cellulase on cellulose. The maximum amount of adsorbed cellulase (370.37 FPU/g) was obtained from SBP (at 80 °C), which was 37 % more than that of the control. Additionally, the reducing sugar yield, initial hydrolysis rate, and maximum catalytic efficiency were 121 %, 202 %, and 125 % more than that of the control, respectively. Aqueous ammonia provided a good approach for improving enzymatic digestibility of cellulose through weakening the interactions between lignin and cellulose, which might be a suitable pretreatment in fuel ethanol production from SBP.