Stabilization of Polysaccharides During Alkaline Pre-Treatment of Wood Combined with Enzyme-Supported Extractions in a Biorefinery

Specific enzymes have demonstrated an ability to increase the possibilities for extracting wood polymers. Enzymatic treatment requires an open wood structure, which was achieved by extended impregnation of the wood. However, lignin and some of the hemicelluloses, primarily glucomannan, were lost during the impregnation. To improve the carbohydrate yield, three glucomannan modification agents—sodium borohydride, polysulphide, and anthraquinone—were used, which increased the yields of the impregnated materials from 76.6% to 89.6%, 80.0%, and 81.3%, respectively. Through the use of additives, most of the glucomannan could be retained in the wood while still allowing the enzymes to penetrate the wood and attack the polymers. The additives also increased the extraction yield from 9 to 12% w/w wood. Gamanase treatment prior to the extraction increased the extraction yield to 14%. Of the three stabilizing agents, sodium borohydride was the most efficient, providing the highest extraction yields.