This slurry
was homogenized for 5 min to ensure that the solids were uniformly
dispersed. The pulp was then pretreated in an autoclave for
30 min at 121 C and 1 atm and vacuum filtered (GAST Manufacturing,
Inc., Model DOA-P704, Michigan, USA). The solid residue
(denoted as CAB – H) was washed with water until the wash water
reached a pH of 6.0 ± 0.5; it was then dried at 50 C for 24 h. The
filtered liquid hydrolyzate fraction was adjusted to a pH of
6.5 ± 0.2 with Ca(OH)2 and filtered to remove the precipitate that
was formed.