Improved upstream processing for detoxification and recovery of xylitol produced from corncob

This work deals with the development of an improved process for xylitol production from corn cob hydrolysate by biotechnological routes emphasizing the detoxification of corncob acid hydrolysate. The acid hydrolysate obtained by acid hydrolysis of corn cob was concentrated and detoxified by activated charcoal, membrane process and ion exchange resin process. The resultant partially purified corncob hydrolysate was used in fermentation. The fermentation of acid hydrolysate containing 56.5 g/L xylose was carried out in a 14 L fermenter at pH 4.5 for 48 h with 150 rpm stirring rate at 30 °C. A xylitol yield of 62% was achieved from the partially purified acid hydrolysate medium during fermentation using Candida tropicalis MTCC 6192. The purity of xylitol was increased to 92-94% upon downstream processing of carbonation, subsequently ion exchange process and activated charcoal.