The chemical composition of lipophilic extractives in paper pulps from Eucalyptus globulus wood during
kraft cooking followed by TCF (“totally chlorine free”) and ECF (“elemental chlorine free”) bleaching
sequences has been determined by gas chromatography and gas chromatography-mass spectrometry.
The chemical analyses revealed that the composition of the lipophilic extractives in pulp after kraft cooking
and TCF bleaching with hydrogen peroxide was similar to that of E. globulus wood extractives, sitosterol
and sitosterol esters being the predominant compounds. In contrast, the presence of these compounds
was almost negligible in pulp after ECF bleaching with chlorine dioxide and only the saturated
sterol stigmastanol, in both free and esterified forms, survived the bleaching.
The fungal degradation of lipophilic extractives in sapwood and heartwood from Scots pine (Pinus sylvestris) was studied. In sapwood, the white rot fungi, Bjerkandera sp. and Funalia trogii, removed higher amounts of extractives than the sapstain strains, Ophiostoma ainoae and Ceratocystis allantospora. Triglycerides, long chain fatty acids, steryl esters and waxes in pine sapwood were almost completely degraded by all the fungi. Sterols and resin acids were also extensively degraded by the white rot strains; however, these components were not or only poorly removed by the sapstain fungi. The removal of total extractives by all the fungal strains was higher in sapwood as compared to heartwood. The highly concentrated extractive fraction in pine heartwood mainly consists of resin acids. As observed in sapwood, sapstain were also poorly effective in the degradation of the resin acids present in heartwood. The fungal degradation of heartwood extractives was not only limited by the degradative ability of the various test microorganisms, but also by the inhibitory effect exerted by the extractive fraction. The white rot fungus F. trogii was particularly inhibited on heartwood. Bjerkandera sp. showed a higher tolerance to toxic extractives and was the most efficient fungus in degrading extractive constituents in both Scots pine heartwood and sapwood. Therefore, Bjerkandera sp. strain BOS55 should be considered as a potential agent for pitch control in pulp and paper manufacture.
The composition of lipophilic extractives in the chloroform soluble fraction of the acetone extract from Eucalyptus globulus wood has been examined. The lipid extract was fractionated by solid-phase extraction on aminopropyl-phase cartridges into four different fractions of increasing polarity. The total lipid extract and the resulting fractions were analyzed by gas chromatography and gas chromatography-mass spectrometry, using high temperature capillary columns. The main compounds identified included sterols, sterol esters, fatty acids, steroid ketones, hydrocarbons and triglycerides. Minor compounds such as fatty alcohols, mono- and diglycerides, waxes and tocopherols were also identified among the lipids from E. globulus wood.