Abstract: The effects of xylanase treatment with variable enzyme dosage under different pH and temperature on the changes of chemical composition, pulp yield, and fiber morphologies were investigated in this study. The results indicated the homemade xylanase was a thermostable and alkaline-tolerant complex enzyme with minor parts of pectinase and cellulase, and could be applied in a wide range of pH and temperature. The optimized enzyme treatment conditions were 2.0 U/g of enzyme dosage, 50℃ of reaction temperature and pH 8.0, respectively. The holocellulose, hemicelluloses and lignin contents declined with the enzyme dosage increasing. The pulp yield exceeded 95% under this optimized reaction temperature and pH,. The swollen fiber walls and coarse fiber surfaces were observed after the enzyme treatment. The fiber porosity and specific surface area increased as well. This could improve the penetration and reactivity of the chemicals in aspects of physical, chemical and biological acting processes, and was beneficial to improve the bio-refinery efficiency.

Key words: complex xylanase, mulberry core, chemical composition, fiber morphology