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The lipophilic and hydrophilic extractives in the sapwood (sW) and heartwood (hW) of stems fromPinus halepensisMill andEucalyptus camaldulensisDehnh trees grown in the north of Algeria were analyzed. The extraction of dried samples was carried out in an accelerated solvent extractor (ASE). The lipophilic substances were first extracted withn-hexane and then the hydrophilic ones with acetone/water. The extractives were analyzed by gas chromatography-flame ionization detection (GC-FID), GC-mass spectroscopy (MS) and high-performance size-exclusion chromatography (HPSEC). The largest amount of lipophilic extractives (≈13.4 mg g−1) was observed in the hW ofP. halepensis, while the hW ofE. camaldulensiscontained the largest amount of hydrophilic extractives (≈116.3 mg g−1). Lipophilic extractives are mainly composed of oleoresins (resin acids, terpenes), fats (fatty acids, glycerides, steryl esters, sterols) and waxes (fatty alcohols). Hydrophilic extractives are composed of polyphenols (stilbenes, flavanols), sugars (monosaccharides) and sugar alcohols (cyclic polyols). The main identified lipophilic extractives are resin acids in pine and glycerides in eucalypt. The main identified hydrophilic extractives are cyclic polyols in pine and flavanols and monosaccharides in eucalypt. The total content of extractives is higher in hW than in sW.

The effectiveness of pressurized hot-water extraction conditions for obtaining galactoglucomannans (GGMs) from Pinus halepensis suitable for applications like coatings and films packaging was investigated. For this purpose, high molar masses with high yields are required, presenting a serious challenge for hot-water extraction processes. The extraction of GGMs was carried out in an accelerated solvent extractor (ASE) and the isolation was performed by precipitation in ethanol. Three temperatures in the range 160–180 °C and five extraction times 5–90 min were tested in order to optimize extraction parameters of GGMs, avoiding thermal and chemical degradation in hot-water. Total dissolved solids (TDS) were determined gravimetrically after freeze-drying and weight average molar masses (Mw) were determined by high-performance size exclusion chromatography (HPSEC). Total non-cellulosic carbohydrates were determined by gas chromatography (GC) after acid methanolysis. Free monomers were additionally analyzed by GC. Lignin in water extracts was measured by an ultraviolet (UV) method. Acetic acid was determined after alkaline hydrolysis of acetyl groups and analyzed by HPSEC. The main parameters influencing the extraction processes of the GGMs, namely, extraction time and temperature were studied. Optimal extraction parameters of GGMs were identified at 170 °C and 20 min extraction time, with average Mw of extracted fraction of 7 kDa leading to a GGM yield of approximately 56 ${\text{mgg}}_{\text{o}.\text{d}.\text{m}}^{-1}$, corresponding to 6% on dry wood basis.

Bark wastes today are viewed as a high-value resource for biorefinery due to their chemical richness and diversity. This work presents a comprehensive chemical characterization of the inner bark and the outer bark of Eucalyptus camaldulensis cultivated in Algeria. The extractives were first isolated with an Accelerated Solvent Extractor (ASE) and then analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The content of pre-extracted bark in cellulosic polysaccharide and free sugar monomers was determined by Gas Chromatography (GC). The hemicellulose composition and amount was determined after the acid methanolysis and GC. The amount of lignin was determined gravimetrically by the Klason lignin method and the acid soluble lignin was determined by the UV method. Formic and acetic acids in the bark were determined by HPLC after alkaline hydrolysis. It was found that the extractives content were similar in the outer bark (0.85%) and the inner bark (0.88%). The cellulose content was higher in the outer bark (33.4%) than in the inner bark (28.7%). Lignin and the total hemicellulose contents were more abundant in the outer bark (31.7, 26.2%) than in the inner bark (28.6, 19.3%) whereas, sugar monomers were more abundant in the inner bark (4.4%) than in the outer bark (3.8%). The variation in acetic and formic acids and ash contents between the outer bark (1.5, 0.006 and 2.5%) and the inner bark (1.3, 0.005 and 2.4%) was small. The obtained results showed that the bark can be considered a suitable feedstock for lignocellulosic biorefinery and also for the extraction of bioactive compounds that can be used in different sectors.