2.3. Enzymatic hydrolysis
The cellulase (45 FPU/g substrate)was added to 50mMsodium citrate buffer
(pH 4.8) supplemented with 0.02% (w/v) sodium azide to inhibit microbial contamination,
and then mixed to the substrate in a concentration of 2% (w/v). The
experiments were carried out in 125-ml Erlenmeyer flasks containing 25 ml total
reaction volume (the buffer–enzyme mixture). The flasks were sealed with a plastic
film and incubated in a rotary shaker at 100 rpm, 45 ◦C during 96 h. To follow
the hydrolysis, a flask was withdrawn at different times and the reaction mixture
was immediately centrifuged at 4000 rpm for 10 min, to remove solids. The liquid
phase (hydrolyzate)was heated for 5 min on a boilingwater bath to precipitate the
protein and prevent further hydrolysis. Glucose, cellobiose, xylose and arabinose