Wood Extractives of Silver Fir and Their Antioxidant and Antifungal Properties

The chemical composition of extractives in the sapwood (SW), heartwood (HW), knotwood (KW), and branchwood (BW of silver fir (Abies alba Mill.) was analyzed, and their antifungal and antioxidant properties were studied. In addition, the variability of extractives content in a centripetal direction, i.e., from the periphery of the stem towards the pith, was investigated. The extracts were analyzed chemically with gravimetry, spectrophotometry, and chromatography. The antifungal and antioxidative properties of the extracts were evaluated by the agar well diffusion method and the diphenyl picrylhydrazyl radical scavenging method. Average amounts of hydrophilic extractives were higher in KW (up to 210.4 mg/g) and BW (148.6 mg/g) than in HW (34.1 mg/g) and SW (14.8 mg/g). Extractives identified included lignans (isolariciresinol, lariciresinol, secoisolariciresinol, pinoresinol, matairesinol) phenolic acids (homovanillic acid, coumaric acid, ferulic acid), and flavonoids epicatechin, taxifolin, quercetin). Secoisolariciresinol was confirmed to be the predominant compound in the KW (29.8 mg/g) and BW (37.6 mg/g) extracts. The largest amount of phenolic compounds was extracted from parts of knots (281.7 mg/g) embedded in the sapwood and from parts of branches (258.9 mg/g) adjacent to the stem. HW contained more lignans in its older sections. Hydrophilic extracts from knots and branches inhibited the growth of wood-decaying fungi and molds. KW and BW extracts were better free radical scavengers than HW extracts. The results of the biological activity tests suggest that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties. The results of this study describe BW as a potential source of phenolic extractives in silver fir.

The Wooden Roof Framing Elements, Furniture and Furnishing of the Etruscan Domus of the Dolia of Vetulonia (Southern Tuscany, Italy)

The Etruscan Domus of the Dolia remained hidden until 2009, when archaeological excavations began in the Etruscan–Roman district of Vetulonia (Southern Tuscany). Based on the classification of the archaeological materials recovered, the destruction of the Domus and the Etruscan city of Vetulonia was traced back to the 1st century BC. The highly various and precious materials recovered inside the Domus revealed the richness of the building and its inhabitants. With this study, we present the anthracological analyses from the Domus of the Dolia. Wood charcoals were recovered from different house rooms, which had different functions based on the archaeological evidence. The tree species employed for the construction of the roof of the building were deciduous and semi-deciduous oak wood (Quercus sect. robur, Quercus sect. cerris) and silver fir wood (Abies cf. alba). Evergreen oak wood (Quercus sect. suber), boxwood (Buxus sempervirens), beech wood (Fagus cf. sylvatica), maple wood (Acer sp.) and cherry wood (Prunus cf. avium) were adopted for the furniture and furnishings of the house. Moreover, wood charcoal fragments of fruit trees belonging to the family of Rosaceae were identified, documenting a possible garden inside the court of the house. The study shows the use of the local tree species primarily. The silver fir wood and beech wood were likely sourced from the nearby (roughly 60 km) Mount Amiata.

Surface Modification of Spruce and Fir Sawn-Timber by Charring in the Traditional Japanese Method—Yakisugi

The traditional Japanese method of wood surface charring was studied. To perform the surface charring, three sawn Norway spruce and Silver fir wood boards of dimension 190 × 24 × 4000 mm3 were tied together to act as a chimney and charred in a short time (3–4 min) with open flame at a temperature above 500 °C. Temperature inside the chimney was recorded on the three different positions during the charring process. Surface temperature of spruce increased from 0 °C to 500 °C in approx. 120–300 s while fir increased in approx. 100–250 s. The thickness of the charred layer and the resulting cupping effect were investigated at the different heights of the chimney to evaluate its variability. Temperature achieved during the charring process was sufficient to get a significant charred layer of 2.5 and 4.5 mm on average for spruce and fir samples, respectively. The analyzed samples showed a significant cupping effect to the charred side with no difference between the annual ring orientation of sawn boards. Spruce exhibit a more significant cupping effect when compared to fir, i.e., 3.2–6 mm and 2.2–4.5 mm, respectively. Furthermore, the pH values of charred samples increased significantly, which could be an indication of improved resistance against wood-decay fungi. For better insight into the traditional charring method, further studies should be carried out to execute the charring process in a consistent quality and therefore fully exploit its potential.

In-depth studies on the modifying effects of natural ageing on the chemical structure of European spruce (Picea abies) and silver fir (Abies alba) woods

Wood is usually stable under relatively dry conditions but may still undergo slow deterioration. The type of deterioration and how these processes affect the wood are important questions that need consideration if old wooden structures are to be studied and properly preserved. The aim of this paper is to establish the main structural and morphological differences between new and naturally aged European spruce (~ 150–200 years) and silver fir wood (~ 150 years). Naturally aged European spruce (a) was sourced from an outdoor part of a building constructed in the seventeenth century and naturally aged European spruce (b) were obtained from a furniture item located in a historical building from the eighteenth century. The principal age-induced changes in fir are the degradation of C–O and C=O groups in hemicellulose, according to the FTIR analysis. Degradation of cellulose and hemicelluloses was observed for spruce, with a greater effect seen in the indoor aged sample. X-ray photoelectron spectroscopy (XPS) showed that after aging C–C/C–H peaks were smaller in the spruce and fir samples, while C–O and O–C–O peaks were larger. The crystallinity index (CrI) obtained by X-ray diffraction showed that due to weathering the CrI of naturally aged spruce (a) increased compared to the new wood. The CrI of the aged spruce (b) and aged fir was lower than in the new woods. The ratios for the spruce sample, which aged indoors, were higher than those for the one aged outdoors. According to the observations made in this study, hemicellulose and cellulose are easily degraded under environmental conditions.

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.