(161f) Biorefinery for Xylitol, Lactic Acid and Astaxanthin Production From Corn Cobs

A biorefinery is an integrated process to produce multiple products including fuels and chemicals from renewable resources with low environmental impact. In this research, we experimentally examined the feasibility for producing multiple products including, xylitol, lactic acid and astaxanthin from corn cobs as a feed stock. The corn cobs were first hydrolysed by the dilute acid to obtain to xylose and its residues were then enzymatically hydrolyzed to glucose. By this treatment, hydrolysates containing approximately 27 g-xylose/ l and 30 g-glucose/ l were selectively obtained from 100 g-corn cobs/ l . Using the hydrolysate containing xylose, approximately 18 g/l xylitol was successfully produced by Candida magnolia. The hydrolysate containing glucose was easily utilized for lactic acid production by Lactococcus lactis. Simultaneous enzymatic saccharification and fermentation (SFF) was also effective to produce concentrated lactic acid (approx. 90 g/L) from corn cob residues after dilute sulphuric acid hydrolysis, which mainly contain cellulose. It was also found that the hydrolysates containing xylose and glucose could be used as a favourable source for astaxanthin production using Xanthophyllomyces dentrohous. By incorporating the high value product such as astaxanthin into the biorefinery system, the economic feasibility of the biorefinery was greatly improved. Finally total process evaluation will be presented from the view points of profitability, energy consumption and environmental impact.