Pregled lipofilnih i hidrofilnih ekstraktivnih tvari u tkivima obične bukve

Common beech (Fagus sylvatica L.) is one of the most widespread and economically important tree species in Europe and, therefore, represents a potential source of high value added extractives. The aim of this paper was, therefore, to review the existing data regarding the composition of lipophilic and hydrophilic extractives of beech tissues, and the extraction systems and analytical techniques used for their examination. The lipophilic extractable fraction of beech is characterized mainly by saturated and unsaturated fatty acids, fatty alcohols and sterols while the hydrophilic extractives of beech consist of soluble sugars, i.e. monosaccharides, oligosaccharides, sugar alcohols and sugar acids, as well as of simple phenols and flavonoids. Chromatography has been recognized as the convenient and most frequently used technique for the chemical analysis of extractives. This overview showed that the information about the composition of low-molecular extractives of beech is satisfactory, but the data on oligomeric extractives are still fragmentary.Obična bukva (Fagus sylvatica L.) jedna je od najrasprostranjenijih i gospodarski najvažnijih vrsta drva u Europi i stoga je potencijalni izvor ekstraktivnih tvari visoke dodatne vrijednosti. Cilj rada bio je preispitati postojeće podatke koji se odnose na sastav lipofilnih i hidrofilnih ekstraktivnih tvari u tkivima bukve te sustave za ekstrakciju i analitičke tehnike koje se primjenjuju za njihovo istraživanje. Lipofilne frakcije koje se mogu ekstrahirati iz bukve uglavnom su zasićene i nezasićene masne kiseline, masni alkoholi i sterol, dok se hidrofilne ekstraktivne tvari iz bukve sastoje od topljivih šećera, tj. monosaharida, oligosaharida, šećernih alkohola i šećernih kiselina, kao i od jednostavnih fenola i flavonoida. Kromatografija je prepoznata kao prikladna i najčešće primjenjivana tehnika kemijske analize ekstraktivnih tvari. Ovaj je pregled pokazao da su podaci o sastavu niskomolekularnih ekstraktivnih tvari iz bukve zadovoljavajući, ali su podaci o oligomernim ekstraktivnim tvarima još uvijek fragmentarni

Optimization of accelerated solvent extraction (ASE) of silver fir wood (Abies alba Mill.)

Qualitative and quantitative analysis of wood plant extractives depend on the efficiency of the extraction method used. The aim of this study was the application of the accelerated solvent extraction system ASE 350 to obtain hydrophilic extracts form silver fir wood (Abies alba Mill.) and optimization of the extraction protocol. Silver fir trees originated from Kočevska Reka. Dissected and milled samples of sapwood, heartwood and knots were extracted with the ASE 350 with water, ethanol (95 % aq), acetone (95 % aq) and ethyl acetate. The number of extraction cycles was determined. Analysis of extracts was done by UV/Vis spectrophotometry and HPLC. The most effective solvent for the extraction of phenolic components from heartwood was ethanol (95 % aq), in the case of sapwood water and acetone (95 % aq) in the case of knotwood. Only two 5-minute extraction cycles were required for sufficient extraction yield when using ASE 350 at 100 °C and 103.42 bar

Resistance of polylactic acid/nanofibrillated cellulose composite to scratching

The aim of the study was to prepare a bionanocomposite based on polylactic acid (PLA) with the addition of nanofibrillated cellulose (NFC) as a reinforcement component. For the production of the composite we used unmodified and acetylated NFC (A_NFC). Freeze-dried NFC was acetylated in a heterogeneous system with acetic anhydride in dimethylformamide (DMF) in the presence of pyridine as a catalyst. The success of the acetylation was determined by FT-IR spectroscopy. PLA films were prepared with the addition of 2.5%, 5% and 10% of unmodified and acetylated NFC. The focus of this research was the impact of the NFC additive on the transparency and on the resistance of the bionanocomposite to scratching. The transparency of the bionanocomposite film was measured using UV-Vis spectrophotometry, and the resistance of the films to scratching was evaluated with a scratch test. The optimal amount of NFC and A_NFC added to the polymer PLA to achieve better resistance of the bionanocomposite to scratching was determined. The best resistance of the prepared bionanocomposite to scratching was achieved by the addition of a 2.5% A_NFC to the PLA polymer, which also has minimal reduced transparency with respect to the PLA film. With the highest addition of A_NFC to the PLA polymer, bionanocomposite films with minimal reduction of transparency were obtained

Changes of mechanical properties of wood as a consequence of blue stain fungi activity

Glive modrivke les načeloma samo estetsko razvrednotijo in naj ne bi vplivale na mehanske lastnosti lesa. Da bi to hipotezo potrdili oziroma ovrgli, smo vzorce rdečega bora (0,5 x 1,0 x 20,0 cm) za 2, 4, 6 ali 8 tednov izpostavili delovanju testnih gliv modrivk Aureobasidium pullulans in Sclerophoma pithyophila. Z uporabo nedestruktivnih metod smo vzorcem pred in po izpostavitvi določili maso, modul elastičnosti, kemijske lastnosti (FTIR), barvo površine ter delež ogljika in dušika. Rezultati testa so pokazali, da sprememba mase in kemijske sestave lesa nista bistveni, medtem ko pa se modul elastičnosti rahlo poveča. Po pričakovanju smo določili tudi močno spremembo barve vzorcev, saj so le-ti zelo potemneli. Nazadnje smo z elementno analizo CNS ugotovili padec dušika v okuženih vzorcih. Na osnovi opisanih rezultatov sklepamo, da bi lahko pomodrel les v večjem obsegu uporabljali za konstrukcijski les oziroma za nosilne elemente.Blue stain fungi change visual appearance of wood and supposedly do not influence mechanical properties of attacked wood. To prove or reject this hypothesis, specimens of pine wood (0.5 x 1.0 x 20.0 cm) were exposed to 2 blue stain fungi: Aureobasidium pullulans and Sclerophoma pithyophila for 2, 4, 6 or 8 weeks. Using non-destructive techniques, the following parameters were determined: mass, chemical properties (FTIR), colour of specimens, so as carbon and nitrogen content. Results showed that there are almost no chemical and mass changes: however slightly increased modulus of elasticity was determined. As expected, the colour of the specimens changed to dark tones. Furthermore, CNS analysis showed decrease of nitrogen content in colonized specimens. On the basis of these results, it can be concluded that such wood could be more extensively used for construction purposes

Development of the HPLC method for separation of some phenolic compounds of wood

The most suitable composition of mobile phase for the separation of simple phenolic compounds such as gallic acid, pyrocatechol, phloroglucinol, resorcinol, vanillin and related compound catechin by the high performance liquid chromatography was investigated. The most appropriate developing mobile system for the separation of these organic compounds was acetonitrile and 2% water solution of formic acid with gradient ratio from 2.98 to 25:75. The best separation of the six organic compounds was achieved using mobile phase with lower content of formic acid. HPLC is a method of choice for qualitative and quantitative analysis compounds in various types of samples in the broad field of forestry-wood-pulp-paper chain

Influence of different polar solvents on contents of total phenols in wood extracts

V prispevku smo ovrednotili vpliv treh različno polarnih organskih topil na ekstrakcijo fenolnih snovi iz lesa. Les bukve (Fagus sylvatica L.) in smreke (Picea abies) smo pod enakimi pogoji ekstrahirali z 80 % metanolno, etanolno in acetonsko vodno raztopino. Primernost topil smo ocenili s spektrofotometrično analizo vsebnosti celokupnih fenolov po Folin-Ciocalteu metodi. Rezultati analize kažejo, da sta za ekstrakcijo fenolnih spojin iz bukovine in smrekovih grč izmed uporabljenih topil najbolj primerni vodni raztopini metanola in acetona, pri čemer pa je izbira topila za ekstrakcijo lesnih tkiv odvisna predvsem od raziskovalnih ciljev