The present works investigate hydrothermal pretreatment of oil palm empty fruit bunch and oil palm
frond fiber in a batch tube reactor system with temperature and time range from 170 to 250 C and 10
to 20 min, respectively. The behavior of soluble sugars, acids, furans, and phenols dramatically changed
over treatment severities as determined by HPLC. The cellulose-rich treated solids were analyzed by SEM,
WAXD, and BET surface area. Enzymatic hydrolysis was performed from both pretreated slurries and
washed solid, and data obtained suggested that tannic acid derived from lignin degradation was a potential
cellulase inhibitor. Both partial removal of hemicellulose and migration of lignin during hydrothermal
pretreatment caused structural changes on the cellulose–hemicellulose–lignin matrix, resulting in the
opening and expansion of specific surface area and pore volume. The current results provided important
factors that maximize conversion of cellulose to glucose from oil palm biomass by hydrothermal process.