Effect of enzymatic high temperature prehydrolysis on the subsequent cellulose hydrolysis of steam‐pretreated spruce in high solids concentration

Abstract

AbstractBACKGROUNDHigh‐temperature enzymatic hydrolysis of cellulose has been studied recently with promising results. High temperatures can improve reaction rates and mass transfer, and lower viscosity. Tests were made to determine how short high‐temperature prehydrolysis steps affect the final hydrolysis with commercial cellulase mixture.RESULTSContinuous mixing improved the hydrolysis of 3% Avicel by Pyrococcus horikoshii endoglucanase (PhEG) at 70°C but not at 100°C. Differences in the temperature effect between 90°C and ∼103°C were much higher than between 70°C and 90°C. It was essential that the dosed enzyme activity was the same at each temperature, meaning lower volumetric amount of enzyme at higher temperature. PhEG prehydrolysis (2 h) of steam pretreated spruce before final hydrolysis by commercial cellulase mixture was more efficient at 100°C than at 80°C, improving the total enzymatic hydrolysis of cellulose by 15–30%. Xylanase and mannase prehydrolysis at 80°C (2 h) improved the cellulase hydrolysis by 20–33%, while all three enzymes together improved the final enzymatic yield by 50–70%.CONCLUSIONA temperature of 100–105°C provides clear process advantages for enzymatic treatments when compared with 70–90°C. Enzymatic high‐temperature prehydrolysis could be applicable to circumvent the problems of high viscosity and to reduce the required amount of cellulases in the subsequent hydrolysis. © 2015 Society of Chemical Industry