Biobleaching of pulp from oil palm empty fruit bunches with laccase and xylanase

Laccase and xylanase were tested for their suitability for biobleaching of soda-anthraquinone pulp from oil palm empty fruit bunches (EFB). An enzymatic stage with xylanase (X) and/or laccase (L) was incorporated before the alkaline extraction stage (E) and the hydrogen peroxide bleaching stage (P). Compared with controls, the LEP sequence resulted in an improvement of optical properties (brightness and colorimetric properties) and a reduction of the kappa number. When xylanase and laccase were used jointly, no improvement was detected, however, when the xylanase application preceded the laccase stage, the beneficial effects of laccase were boosted. Thus, the final XLEP bleached pulp showed a kappa number of 5.4 and a brightness of 60.5% ISO, although the hydrogen peroxide consumption increased (77.0% vs. 64.5% and 73.8% for EP and LEP respectively). Finally, after subjecting the bleached pulps to accelerated ageing, the best optical properties were observed in the XLEP pulp.