HEMICELLULASE-ASSISTED BLEACHING OF MODIFIED KRAFT PULP PRODUCED WITHPOLYSULFIDE ADDITION

The increased retention of hemicelluloses, particularly glucomannan, d uring polysulphide pulping may affect the pulp's response to hemicellu lase-assisted bleaching, possibly in the same way as postulated for re deposited xylans. MCC (modified continuos cooking) pulp prepared in th e laboratory with and without polysulphide (PS) addition was examined for hemicellulase-assisted bleaching with purified xylanase and mannan ase from Trichoderma reesei. Glucomannan solubilization during mannana se treatment,vas not increased for MCC/PS pulp over reference MCC pulp , suggesting that the yield gain for MCC/PS pulp was maintained. Impro vements to chlorine dioxide (DED) and hydrogen peroxide (QPPP) bleachi ng hemicellulase treatments were also unaffected by polysulphide addit ion to modified kraft pulping.