Xylitol production from Eucalyptus wood hydrolysates extracted with organic solvents

Overliming and extraction of acid hydrolysates of Eucalyptus wood were assayed as pretreatments to improve the bioconversion of xylose into xylitol by Debaryomyces hansenii. Chloroform, trichloroethylene, ethyl acetate, diethyl ether and hexane were utilized for extraction, directly or after overliming of hydrolysates. Under selected conditions, charcoal adsorption of extracted hydrolysates was assayed as a means of enhancing bioconversion. The best pretreatments assayed were extraction of overlimed hydrolysates with ethyl ether, with or without further charcoal adsorption. With these processing schemes, volumetric productivities of xylitol in the region of 1.1 g litre(-1) h(-1) and product yields near 0.7 g xylitol g(-1) xylose were obtained. (C) 1997 Elsevier Science Ltd.