Changes in the content of extractives in silver fir (Abies alba Mill.) bark due to different storage conditions

Abstract The circular economy promotes the use of industrial by-products as raw materials for high-quality products. Silver fir bark ( Abies alba Mill.), a low-value residue from wood processing, is a rich source of polyphenols with antioxidant properties. This study investigated how bark preparation (particle size) and storage conditions affect the content of total extractives, polyphenols, and condensed tannins in aqueous extracts over a 10-month period. Bark samples of two particle sizes were stored either outdoors (exposed to precipitation) or indoors (dry, dark conditions). The extracts were analyzed monthly by gravimetry and UV-Vis spectrophotometry. The results showed that both particle size and storage conditions significantly influenced the retention of extractives and polyphenols in the samples. The highest losses occurred in ground bark samples stored outdoors, while the best retention was achieved with larger bark particles stored in a covered, dry environment. These findings highlight the importance of optimized storage strategies for the preservation of bark quality as a source of bioactive compounds.