Removing Hemicellulose from Pulps by Specific Enzymic Hydrolysis

Abstract

AbstractThe hemicellulose content (solubility in 18% NaOH) of a delignified mechanical aspen pulp was lowered from 23.4% to 18.2% by one-hour hydrolysis with xylanase isolated from the fungus Schizophpllum commune by fractional precipitation. After 24 h hydrolysis, the hemicellulose content was reduced further to 12.9%. The predominant hydrolysis products, xylose and xylobiose, confirmed the specificity of hydrolysis. A crude mixture of cellulolytic and hemicellulolytic enzymes from the same microorganism gave glucose as the major hydrolysis product, and a pulp with higher relative hemicellulose content. Xylan-specific hydrolysis of a low-yield sulfite pulp gave only a small decrease in pentosan content.