DOI 10.1007/s00253-006-0346-1 ENVIRONMENTAL BIOTECHNOLOGY

Abstract Lipophilic extractives in wood and other lignocellulosic materials exert a negative impact in pulp and paper manufacturing causing the so-called pitch problems. In this work, the appropriateness of an enzy-matic treatment using the laccase–mediator system for pitch biocontrol is evaluated. With this purpose, three pulp types representative for different raw materials and pulping processes—eucalypt kraft pulping, spruce thermomechan-ical pulping, and flax soda-anthraquinone pulping—were treated with a high-redox-potential laccase from the basidiomycete Pycnoporus cinnabarinus in the presence of 1-hydroxybenzotriazole as a redox mediator. The gas chromatography and gas chromatography/mass spectrom-etry analyses of the lipophilic extractives from the enzy-matically treated pulps revealed that the laccase–mediator treatment completely or greatly removed most of the pitch-causing lipophilic compounds present in the different pulps including: (1) free and conjugated sitosterol in eucalypt paper pulp; (2) resin acids, sterol esters, and triglycerides in spruce pulp; and (3) sterols and fatty alcohols in the flax pulp. Different amounts of free and conjugated 7-oxosterols were found as intermediate products in the oxidation of pulp sterols. Therefore, the laccase–mediator treatment is reported as an efficient method for removing pitch-causing lipophilic compounds from paper pulps obtained from hardwood, softwood, and nonwoody plants