Abstract

The object of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pretreated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pretreated material. Glucose yields after enzymatic hydrolysis of pretreated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR Imaging; these microscopic techniques show changes in the physical and chemical characteristics of pretreated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pretreated lignocellulose.