## 1 Introduction  
In ancient times, the contact of food products with wood was primarily related to their storage and transport. Drinks and other food products were stored and transported in wooden barrels, which were relatively light and durable [1, 2]. Currently, wood is used primarily because of its interesting and valuable active compounds that shape the aroma, taste and colour of drinks. Currently, acid-resistant steel tanks and containers are employed for both the ageing and transport of wine. Barrels are primarily used for the ageing of alcoholic beverages, particularly those with distinctive qualitative and sensory characteristics, including grape wines, whisky, brandy and cognac. The chemical compounds derived from wood exert a profound influence on the properties of these beverages, including their antioxidant activity, taste and smell [3, 4]. The active ingredients derived from wood can be divided into two categories: those occurring naturally in the wood and those resulting from thermal treatment. Oak wood, which is most often used for wine maturation, contains approximately 45% cellulose, 25% hemicellulose, 20% lignin and 10% of other active compounds that are of particular importance in winemaking. These include alcohols, esters, terpen, steroids, terpenoids, lactones and phenols [5, 6]. Phenolic compounds, particularly those of low molecular weight, impart asstringency and bitterness to beverages and turn them darker in colour. Furthermore, they influence the antioxidant potential of beverages. 4-Ethylphenol and 4-vinylphenol smell similar to medicines and leather, respectively [7]. Guaiacol and its derivatives (4-methylguaiacol, 4-ethylguaiacol and 4-vinylguaiacol) impart an aroma described as smoky, spicy, toasted, oak and clove-like [6; 8]. Among the phenolic compounds, ellagitannins are most easily extracted by wine and other alcoholic beverages. Castalagin, vescalagin, grandinin and roburin have strong antioxidant properties but also impart astringency to wines [9; 10; 11; 12]. Lactones, which occur in very low concentrations, also contribute to the sensory profile of wines, imparting notes of coconut and wood due to their low sensory detection threshold (20-370 ug/L) [2; 5]. The toasting of wood results in the partial thermodegradation of wood components, which alters the profile of active compounds extracted during wine maturation. Modifying the temperature (from 120 to 230 \({}^{\circ}\)C) and thermal treatment times (from 15 to 90 min) resulted in varying degrees of alteration in the properties of wood, which consequently led to a variable profile of active compounds in the chips [1; 13]. The most susceptible to the temperature impact are lignins, hemicelluloses and ellagitannins [14]. As a result of their decomposition, phenolic aldehydes and ketones, volatile phenols, acids and lactones are formed, giving wines the aroma of smoke, wood and vanilla. Thermally treated polysaccharides are precursors of furan compounds responsible for the aroma of bread, nuts and caramel [1; 15]. Furthermore, the effect of temperature has been observed to reduce the concentration of terpenoids, which may contribute to the lower antioxidant potential of extracts [16]. Wooden barrels are expensive and difficult to obtain, and their use results in the loss of drink due to evaporation through the porous structure of the wood. An alternative is to use wood chips. This solution is much cheaper, and the contact surface of the wine with the wood chips is more developed than when using barrels [3; 17]. The use of wood chips also allows the use of other than oak tree species when ageing wines and other alcoholic beverages. Other wood species are typically distinguished by their greater porosity, which consequently affects the extraction of active compounds from wood into the beverage. The composition of wood species other than oak also varies.