Characterization of bark, needles and cones from silver fir (Abies alba mill.) towards valorization of biomass forestry residues

Valorization of renewable biomass forestry gains more and more interest due to the exhaustible nature of fossil based resources and their negative environment impact. Therefore, this study involves thoroughly characterization of bark, needles and cones from silver fir (Abies alba Mill.) of two different ages (40 and 100 years) to determine their potential use as source of valuable compounds. Proximate/ultimate and compositional analysis as well as thermal behavior showed that the studied materials are promising candidates for biomass valorization by torrefaction and pyrolysis. In addition, it was revealed that fir samples contain significant amounts of phenolic and flavonoid compounds. The extractive fractions were found to be rich in highly valuable compounds such as terpenes, paraffins, phenols, acids and derivatives of abietic acid. This induced good antioxidant activity of the extractive fractions, with fast scavenging of DPPH radicals. The PCA and hierarchical clustering used for exploratory data analysis offered the possibility to combine multiple information obtained from detailed characterization of samples into a global view of the system. This allowed us to observe and distinguish similarities and differences among samples according to source and age. Needles stand out from bark and cones due to the high content of terpenes in extractives. Paraffins were the main components in the extractives from cones. Saccharides were found, in small amounts, only in the extractives of bark. Differences by age were also observed. The resulted outcomes provide a promising starting point in selecting suitable sources and procedures for valorization of renewable biomass forestry into energy and value added materials.