Wood processing industry by-products as a source of natural bioactive compounds

The chemical composition of several by-products, chips, screw waters, and concentrates from a fiberboards manufacture green industrial process, which only employs wood and water, was deeply evaluated. The three by-products analyzed represent different steps of the industrial process. In addition, different types of wood: pine, walnut, chestnut, oak and cherry tree, were evaluated. For all of them, total polyphenols content, and antioxidant activity have been assessed, showing significant differences. To characterize the volatile compounds, an environmentally friendly technique, solid-phase microextraction has been employed. Besides, aqueous and generally recognized as safe organic extracts obtained from the by-products have been prepared, and their chromatographic fingerprint was obtained by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry to identify extractable organic wood components. Significant differences were observed between the studied by-products and wood types. More than 30 different compounds were successfully identified in the screw waters, and concentrates, including terpenes, sesquiterpenes, or polyphenols. Regarding the obtained extracts, up to 30 compounds were identified in the chips, screw waters, and concentrate extracts, highlighting the presence of 13 polyphenols in the cherry tree chips and more than 20 compounds with interesting properties in the concentrate extracts. This work contributes to improve the knowledge about the chemical composition of several wood industry by-products, which could be exploited to obtain natural extracts with added value for their reuse in the food, cosmetic, or pharmaceutical industry, reducing also the environmental impact of the industrial activity.