La. Alves et al., PRETREATMENT OF SUGARCANE BAGASSE HEMICELLULOSE HYDROLYSATE FOR XYLITOL PRODUCTION BY CANDIDA-GUILLIERMONDII, Applied biochemistry and biotechnology, 70-2, 1998, pp. 89-98
In order to remove or reduce the concentrations of toxic substances pr
esent in the sugarcane bagasse hemicellulose hydrolysate for xylose-to
-xylitol bioconversion, the hydrolysate was pretreated by changing the
initial pH level through the combination of different bases and acids
with or without the subsequent addition of activated charcoal. Attent
ion was given to the influence of the fermentation time as well. The e
xperiments were based on multivariate statistical concepts, with the a
pplication of fractional factorial design techniques to identify the i
mportant variables in the process. Subsequently, the levels of these v
ariables were quantified by the response surface methodology, which pe
rmitted the establishment of the best pretreatment procedure with a xy
lose-to-xylitol bioconversion efficiency of 86.2%. This procedure cons
isted in increasing the pH of the hydrolysate from 0.5 to 7.0 with CaO
and reducing it to 5.5 with H3PO4. Next, the hydrolysate was treated
with activated charcoal (2.4%). The highest xylitol yield (0.79 g/g) c
orresponded to a productivity of 0.47 g/L/h.