DILUTE-ACID HEMICELLULOSE HYDROLYSATES FROM CORN COBS FOR XYLITOL PRODUCTION BY YEAST

Dilute acid hemicellulose hydrolysate, comprised mainly of xylose, was obtained from ground corn cobs after dilute hydrochloric acid (2%, wt ) hydrolysis at 100 degrees C for 2 h. Similar acid hydrolysate was al so obtained after the corn cobs were treated with 10% ammonium hydroxi de at 26 degrees C for 24 h. Neutralized hydrolysates containing ca. 1 30 g/l xylose were used as the substrate for xylitol production by a x ylitol-producing yeast Candida sp. 11-2. Ammonia-treated hydrolysate w as a better substrate for xylitol production. Xylose was consumed with in 36 h with a specific xylitol productivity of 1.94 g/l.h and a xylit ol weight yield of 0.57 g/g xylose utilized. In contrast, neutralized hemicellulose hydrolysate obtained without prior ammonia treatment req uired anion exchange resin treatment to be fermented by yeasts. The sp ecific productivity and weight yield of xylitol from anion exchange re sin-treated hydrolysate were comparable to that from an ammonia-treate d sample. (C) 1997 Published by Elsevier Science Ltd.