Enzymes and chelating agent in cotton pretreatment

Desized cotton fabric and cotton seed-coat fragments (impurities) have been treated with commercial cellulase (Celluclast 1.5 L), hemicellulase-pectin ase (Viscozyme 120 L) and xylanase (Pulpzyme HC) enzymes. Seed-coat fragmen ts hydrolyzed much faster than the cotton fabric itself. This relative diff erence in hydrolysis rates makes possible a direct enzymatic removal of see d-coat fragments from desized cotton fabric. Addition of chelating agents s uch as ethylenediamine-tetra-acetic acid (EDTA) markedly enhanced the direc ted enzyme action. Pretreatments carried out in acidic solution at pH 5 inc reased the lightness of seed-coat fragments, contrary to the samples treate d in neutral medium at pH 7. Alkaline scouring resulted in darker seed-coat fragments except for the samples pretreated with Pulpzyme HC plus EDTA. Th is effect is similar to that observed in the biobleaching process in pulp a nd paper industry. (C) 2001 Elsevier Science B.V. All rights reserved.