Volatile terpene extraction of spruce, fir and maritime pine wood: supercritical CO2 extraction compared to classical solvent extractions and steam distillation

Abstract

Abstract To evaluate the potential recovery rate of volatile terpenes from pulp mills, different extraction methods were performed on fir, spruce and maritime pine, and the extracts were analyzed by gas chromatography-flame ionization detector/mass spectroscopy (GC-FID/MS). The results obtained by traditional solvent extraction in the Soxhlet and the accelerated solvent extraction (ASE)® apparatus were compared with those of steam distillation technology (Clevenger), and supercritical CO2 (SC-CO2) extraction was also tested as an interesting alternative to extraction with liquid organic solvents. ASE®-Dionex applied on freeze-dried samples with successive extraction with n-hexane and acetone/water (95/5) was not suitable for volatile compounds. Steam distillation applied on fresh and ground samples was very specific of volatiles, but did not allow complete extraction. Soxhlet extraction performed on fresh and ground samples with successive application of acetone and acetone/cyclohexane (1/9) gave the most representative quantification of ground wood chips, together for volatile terpenes, resins and fatty-acid-type compounds. SC-CO2 [20 and 30 MPa, 60°C modified by 5% ethanol (EtOH)] is able to extract most of the terpenes, terpenoids and fatty-acid-type compounds, but the extraction rates of volatiles were very limited because of a pre-drying step (freeze-drying and crushing). Other lipophilic extractives were also recovered to a lesser extent.