Laccase-Mediator System: the Definitive Solution to Pitch Problems in the Pulp and Paper Industry?
Lipophilic extractives in wood and other lignocellulosic materials exert a highly negative impact in pulp and paper manufacturing causing the so-called pitch problems that affect both paper machine runnability and product quality, among others. Some biotechnological products have been developed and enzymes (lipases) have been successfully applied to softwood mechanical pulping at mill scale. However, the enzymes and microbial inocula used till present are only effective on specific raw materials and processes. Recently, we have shown for the first time the effectiveness of the laccase-mediator system (LMS) in removing pulp lipids regardless the pulping process and the raw material used. The results have been included in a patent recently deposited. In these studies, three pulps representative for different pulping processes and raw materials - including eucalypt kraft pulping, spruce thermomechanical pulping (TMP), and flax soda-anthraquinone (AQ) pulping - were treated with laccase in the presence of 1-hydroxybenzotriazole (HBT) as a redox mediator. The gas chromatography and gas chromatography/mass spectrometry analyses of the acetone extracts from the enzymatically-treated pulps revealed that most of the lipophilic compounds present in the different pulps were efficiently removed using the LMS. Free and conjugated (as esters and glycosides) sitosterol, the main compounds responsible of pitch deposits in the manufacturing of eucalypt kraft pulp, were completely removed. In spruce TMP pulp, LMS degraded most of the resin acids, as well as sterol esters and triglycerides. In the flax soda-AQ pulp, the main lipophilic compounds present including sterols and long chain fatty alcohols were almost completely removed. Small amounts of oxidation products (including 7-oxositosterol, stigmasta-3,5-dien-7-one and 7-oxositosteryl 3β-D-glucopiranoside) were identified confirming the oxidative nature of lipid removal. Pulp and papermaking properties of the enzymatically-treated pulps were also evaluated. In conclusion, LMS treatment is an efficient method to remove pitch-causing lipophilic compounds from hardwood, softwood as well as nonwood paper pulps (at the same time that lignin content is reduced).
| Main Authors: | , , |
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| Format: | comunicación de congreso biblioteca |
| Language: | English |
| Published: |
2006-09-07
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| Subjects: | Lipophilic extractives, Pitch, Laccases, Sterols, |
| Online Access: | http://hdl.handle.net/10261/86433 |
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