Biovalorization of sugarcane bagasse for xylitol and xylooligosaccharides: Kinetic analysis and preliminary feasibility assessment

This study investigated the production of xylitol and xylooligosaccharides (XOS) from xylan in sugarcane bagasse (SB), and assessed their economic feasibility to enhance the overall value of the SB utilization process. Xylitol was produced by fermenting xylose derived through dilute H2SO4 hydrolysis of SB using a newly isolated Candida tropicalis KKU T5. This process yielded 9.5 ± 1.5 g/L of xylitol, with a yield of 0.48 ± 0.04 g/g-xylose. After purification using ethyl acetate, mass balance analysis and economic yield (EY) calculation based on nutrients and chemical costs showed a xylitol yield on SB of 0.068 kg/kg-SB and an EY of 0.002 USD/USD. On the other hand, XOS production was performed using a sequential process, comprising alkaline-hydrogen peroxide extraction of xylan, followed by incomplete hydrolysis of the extracted xylan by xylanase. The extraction process yielded 0.36 ± 0.03 g-xylan/g-SB, and the subsequent enzymatic hydrolysis under statistically optimized conditions gave 10.9 ± 0.1 g/L of XOS, with a yield of 0.30 ± 0.00 g-XOS/g-xylan. Purification of XOS using activated carbon adsorption yielded 0.61 ± 0.09 g-XOS, with an XOS purification efficiency of 30.7 ± 3.9 %. The XOS was shown to selectively support growth of lactic acid bacteria against pathogens. The mass balance analysis showed that the yield of purified XOS on SB was 0.03 kg/kg-SB, and the EY of this process was 0.005 USD/USD. These results demonstrated that xylitol and XOS could be efficiently produced from SB, but XOS presents a higher potential to enhance the overall value of the biomass.