Characteristics of adapted and non-adapted Candida tropicalis InaCC Y799 during fermentation of detoxified and undetoxified hemicellulosic hydrolysate from sugarcane trash for xylitol production

In addition to being effective in extracting xylose from hemicellulose, acid treatment has the potential to produce compounds that inhibit yeast growth during fermentation. Detoxification of hemicellulose hydrolysate and short-term adaptation of yeast to hemicellulose hydrolysate could be applied to overcome this problem in order to increase xylitol production from the hydrolysate. Most studies usually investigated only the effect of detoxification or adaptation of yeast only, and did not compare the two treatments in one particular study. This study investigated and compared the effect of detoxification process and adapting Candida tropicalis InaCC Y799 to sugarcane trash hemicellulose hydrolysate on the production of xylitol during fermentation. The detoxification of hemicellulose hydrolysate was using 1% activated charcoal. The yeast adaptation was conducted by growing the yeast at 50% and 75% diluted sugarcane trash hydrolysate for 24 h. The non-adapted yeast was used in the fermentation of non-detoxified and detoxified hydrolysate, while the adapted yeast was used in the fermentation of non-detoxified hydrolysate. The fermentation was conducted at 30 °C and 150 rpm for 72 h. The yeast adaptation in 75% hydrolysates and detoxification of fermentation medium produced higher xylitol yields (0.54–0.56 g xylitol/g initial xylose; 53.72–54.98% theoretical yield), in a shorter time (24 h) than did the adapted yeast to 50% hydrolysate and non-adapted yeast grown in non-detoxified medium (0.51–0.57 g xylitol/g initial xylose or 50.54–56.59% theoretical yield in 48 h). Therefore, the adaptation of yeast in the higher concentration of hemicellulose hydrolysate (75% hydrolysate) could be used as an alternative strategy to enhance xylitol production beside the detoxification of medium prior to fermentation. Both methods could give the same results in enhancing the xylitol production.