Evaluation of ion exchange resins for removal of inhibitory compounds from corn stover hydrolyzate for xylitol fermentation

The use of dilute acids to catalyze the hydrolysis of hemicellulose to its sugar constituents is well-known and effective. However, a major problem associated with this pretreatment is the poor fermentability of the produced hydrolyzate as a result of the presence of the microorganism's inhibitory compounds. In the present work, seven ion-exchange resins were tested in order to detoxify corn stover hydrolyzate. Regarding xylose recovery, it was observed that more than 92% recovery was feasible. Furfural removal varied from 53.% to 99.%, and hydroxymethylfurfural (HMF) removal was effective between 37% and 100%. Acetic acid was totally removed by Purolite A 103 S resin. Corn stover hydrolyzate (CSH) treated with Purolite A 103 S, and Finex CS 14 GC resins, was tested as substrate for xylitol production using a yeast, Candida mogii. Product yields, Yp/s, of 0.41 and 0.37 g/g and cellular yields, Yx/s, of 0.24 and 0.13 g/g, respectively, were obtained using the two types of resin-treated hydrolyzates.