DETERMINATION OF THE DISTRIBUTION AND REACTION OF POLYSACCHARIDES IN WOOD CELL-WALLS BY THE ISOTOPE TRACER TECHNIQUE .5. BEHAVIOR OF XYLAN DURING KRAFT PULPING STUDIED BY THE RADIOTRACER TECHNIQUE

Behavior of xylan during kraft pulping was studied by the radiotracer technique. Xylan was radio-labeled almost selectively in mature cell w alls of magnolia (Magnolia kobus DC.) by the feeding of myo-inositol-[ 2-H-3] to the growing stem followed by allowing it to metabolize for a long period. The labeled wood meal was treated to kraft pulping, and radioactivities of the black liquor and treated wood meal were determi ned at various stages of the pulping. The results showed that (1) xyla n was dissolved rapidly during the heat-up period, and the dissolution was almost completed before the pulping temperature reached 170 degre es C, (2) 70-80% of the total xylan was dissolved during the pulping, and (3) redeposition of xylan on pulp fibers took place soon after the pulping temperature reached 170 degrees C.