Xylo-oligosaccharides and Ethanol Production from Liquid Hot Water Hydrolysate of Sugarcane Bagasse

Abstract

With the objective of maximizing the use of liquid hot water hydrolysate of sugarcane bagasse, xylo-oligosaccharides and ethanol were respectively produced by the methods of purification and microbial fermentation. The processes of purification with activated charcoal, overliming, solvent extraction, vacuum evaporation, and use of an ion exchange resin were evaluated, and the results indicated that anion exchange chromatography performed well in terms of by-product removal. The recovery and purity of xylo-oligosaccharides reached 92.0% and 90.4%, respectively, using column chromatography with the resin LS30 at a flow rate of 2 mL/min at 25 °C. The hydrolysate was used in ethanol fermentation with Pichia stipitis CBS6054 followed by the production of fermentable saccharides and detoxification. The highest ethanol concentration was 4.12 g/L with a theoretical yield of 47.9% for the hydrolysate after xylanase digestion and resin detoxification, similar to the data of the control experiment, which had an ethanol concentration of 4.64 g/L and a yield of 49.6%. However, the former had a higher ethanol productivity of 0.0860 g/(L∙h), and the highest ethanol concentration appeared 12 to 24 h earlier compared to the control. This study suggests that combined generation of xylo-oligosaccharides and cellulosic ethanol could help maximize profits for a cane sugar factory.