—The use of wood extractives is nothing new in itself, for example, tar was already being produced during the 17th century, explains Professor Janne Jänis from the Department of Chemistry.
—Products many are familiar with include spruce sprout syrup, Abilar resin salve or even a pine-based ice cream. Pulp mills produce tall oil as a by-product, which is further refined into renewable diesel fuel and other technochemical products.
—Wood contains 20–35% of lignin, 40–50% cellulose, and 20–40% hemicellulose. The rest is extractives, metals and other inorganic compounds.
—The amount of extractives is different in heartwood and sapwood, stumps, roots, and inner and outer bark. The largest amount of extractives are found in leaves and needles, and this is what the researchers are currently interested in.
Extractives can be obtained from wood by means of solvent extraction, steam distillation, hydrolysis, and fast and slow pyrolysis.
—One troublesome group of compounds are terpenes, because finding a separation method for them is difficult. For example, pine needles contain over a hundred different volatile compounds, Jänis notes.
Access to raw materials may also present their own challenges. For example, spruce sprouts are only available during a certain time of the year.
—Spruce sprouts contain a lot of antioxidants, vitamins A and C, and terpenes. Quinic acid abundant in spruce sprouts is interesting, because it can be used as a natural starting material for medicine, such as oseltamivir used to treat influenza.