Extraction of cones, branches, needles and bark from Norway spruce (Picea abies) by supercritical carbon dioxide and soxhlet extractions techniques

Four low-value Norway spruce tree fractions - cones, branches, needles and bark, were separated from the main tree constituents for investigation of their lipophilic extractives; in order to identify potential sources of important chemicals for future biorefinery applications. For the first time, conventional soxhlet and supercritical carbon dioxide (scCO2) extraction techniques were used for extraction of organic compounds from these waste fractions. Identification and quantitation were done by silylation and GCMS. Soxhlet extraction led to total yields of 4–5 % for all fractions except for cones, where the extraction yield was approximately 2 %. With scCO2 extraction, the highest yield of extractives was obtained from the branches (ca. 5 %), whereas for needles, bark and cones the yield was approximately 3 %, 2 % and 1 %, respectively. Extracts from all four tree fractions contain fatty/resin acids, terpenes, stilbenes, sterols and some long chain alcohols. The components composition was different for each of the four fractions depending on the extraction technique, for example, stilbenes and sterols from branches are effectively obtained only with scCO2 extraction, whereas soxhlet extraction was more efficient for isolating terpenes, sterols and resin derivatives from cones and bark. Needles extractives, e.g. biologically active sterols and nonacosan-10-ol, important for hydrophobic coatings, can be efficiently obtained by both extraction techniques. These obtained results show that these tree fractions, often discarded or combusted, could generate a potentially important source of nutraceutical, pharmaceutical and commodity chemicals.