Xylitol production from dilute-acid hydrolysis of bean group shells

Xylitol can be obtained from hemicellulosic fraction of lignocellulosic materials containing D-xylose. Bean group shells is an abundant source of hemicellulose, especially pistachio shells. The hemicellulose contents of pistachio shells is approx 50% and consists mainly of xylose. The aims of this study are to optimize the extraction of hemicellulosic sugar xylose from pistachio shells and to produce xylitol using xylose derived from pistachio shlles. Xylose production from pistachio (Pistacia vera L.) shells was carried out using 0.1 similar to 10.0 %(v/v) sulfuric acid. Also, microbial xylitol production from xylose was investigated using Candida tropicalis NBRC 0618. The maximum xylose concentration in the hydrolysate was attained when the pistachio shells were treated at 121 degrees C for 20 min, using 5.0 % (v/v) sulfuric acid. To remove fermentative inhibitors from the hydrolysate, ion exchange resin treatment using both anion and cation exchange resin were found to be effective for detoxification of the hydrolysate. Maximum xylitol productivity was 0.086 g/L/h which is 4.8 higher than the value obtained from untreated samples.