Optimization of acid hydrolysis of sugarcane bagasse and investigations on its fermentability for the production of xylitol by Candida guilliermondii.

The dilute-acid hydrolysis of sugarcane bagasse was optimized using a statistical experimental design resulting in hydrolysates containing 57.25 g/L of xylose, which were fermented with a high inoculum concentration (10 g/L of the yeast Candida guilliermondii IM/UFRJ 50088). The addition of urea reduced the time of conversion (tC) to 75 h (without nitrogen source addition tC > 127 h), and, consequently, improving the rates of xylitol bioproduction. Fermentator experiments, using the optimized conditions, resulted in enhanced conversion rates, reducing tC to 30 h. The stability of the yeast in the hydrolysate was also verified in a 480-h cultivation.