Process optimization for producing xylitol by shaking-flask fermentation from distiller′s grains hydrolysates

Xylitol was produced from hydrolysates of distiller′s grains by Candida tropicalis 1779, and the optimum conditions of the process were found by single-factor experiment and orthogonal test. The fermentations were conducted in 250 mL flasks. The results showed that the satisfied fermentation effect was attained under the technical conditions of inoculum age 27 h, inoculating volume 20mL, liquid volume in flask 100 mL, the addition of nitrogen source 20 mL and nitrogen concentration 48 g/L. Under these conditions, the concentration of xylitol and residual xylose were 11.85mg/mL and 463.51 μg/mL in the fermentation broth, respectively. Under the optimum conditions, the utilization rate of xylose and reducing sugar are 45.62% and 74.81%, respectively. Fermentation experiments showed that it was feasible to produce xylitol by fermentation using lees hydrolysates as a carbon source .