Tons of sugar cane bagasse are produced in Brazil as waste of the sugar
and ethanol industries. This lignocellulosic material is a potential
source for second-generation ethanol production. Diluted acid
hydrolysis is one of the most efficient pretreatments for
hemicellulosic solubilization. The hydrolysate obtained is rich in
xylose, which can be converted to ethanol by Pichia stipitis. This work
used a statistical approach and the severity factor to investigate the
effects of factors associated with the diluted acid hydrolysis process
(acid concentration, solid:liquid ratio and time of exposure) on
various response variables (xylose concentration, hydrolysis yield,
inhibitor concentration and hydrolysate fermentability). The severity
factor had a strong influence on the generation of inhibitors. The
statistical analysis was useful for determining the effects of the
individual factors and their interactions on the response variables. An
acid concentration of 1.09% (vv), an S:L ratio of 1:2.8 (g:ml), and an
exposure time of 27 min were established and validated as the optimum
pretreatment conditions for the generation of hydrolysates with high
xylose concentration and low contents of inhibitors. In such
conditions, hydrolysate with 50 g/l of xylose was obtained