ENZYMATIC DEGRADATION OF POLYGALACTURONIC ACIDS RELEASED FROM MECHANICAL PULP DURING PEROXIDE BLEACHING

Polygalacturonic acids account for about half of the potential ''anion ic trash'' (as measured by polyelectrolyte titration) in peroxide-blea ched mechanical pulp. Pectinase treatment of the bleached-pulp suspens ion or filtrate degrades the dissolved polygalacturonic acid into mono meric galacturonic acid, effectively eliminating the cationic demand c aused by this anionic polyelectrolyte. Pectinase treatment shows promi se as a means of preventing potentially detrimental polygalacturonic a cids from complexing with the cationic polymers that are widely used i n papermaking.