ESR Estimation of Lignin Structure of Japanese Cedar Pulverized Using a Vibration Mill with Ring Media

Abstract

Lignocellulosic biomass has a recalcitrant structure, with hemicellulose and lignin bound tightly to cellulose. Furthermore, lignin might be an inhibitor factor in enzyme reaction. In our earlier study, a vibration mill with ring media was developed to obtain Japanese cedar fine powder, which reached high saccharification efficiency in enzyme reaction. Nevertheless, the influence of lignin was not examined. This study used a lignin quantification test and ESR analysis to assess the influence of lignin in Japanese cedar powder pulverized using a vibration mill with ring media. Lignin quantification test results show that the Klason lignin content of Japanese cedar remained unchanged irrespective of the pulverization time. The ESR analysis results of the radical amount of Japanese cedar revealed that the radical concentration of Japanese cedar was maximized at the pulverization time of 20 min. Results suggest that improvement of the saccharification efficiency of pulverized powder cleaved the lignin binding in the particle, easing access of the enzyme to cellulose.