## 1 Introduction  
Wine is a product that offers a clear example of a saturated market, so winemakers and winegrowers are looking for sustainability and for quality and differentiation to come first. Aroma is undoubtedly one of the most important quality factors, as it provides a profile of identification to wines, as well as being one of the main qualities perceived by consumers, along with colour and taste. Thus, a special emphasis is currently being placed on eenological practices that affect any of these characteristics, whether through agronomic techniques, processes during fermentation or processes during the postfermentation stage. In oenology, the use of wood during fermentation and/or wine ageing processes is a common practice in most wine-producing regions of the world. For centuries, wood has been used to make barrels. Originally built for the need to transport wine, today they are used because they are capable of improving the three main sensory characteristics (aroma, colour and taste) of wine. Such is the importance that wood has acquired that it has gone from only being part of the barrels at the time of ageing red wines to being present throughout the entire winemaking process, from the grapes to the end of the process, in all types of white, rose, red, sparkling, sweet wines, etc., and in all types of alternative formats, barrels, vats of different sizes, etc., and even in bottles made of this material [1]. Oak wood has prevailed in the manufacture of barrels mainly because of its abundance and mechanical resistance. Moreover, this wood positively modifies the characteristics of the wine, acquiring a complex aroma as well as stabilising the colour and improving the clarification and storage of the wine, gaining fame over time [2; 3; 4; 5; 6; 7]. Among the oaks, the most traditional species for wine ageing used are: _Q. alba_ (the so-called American oak), _Q. sessilis_ (_Q. petraea_) and _Q. robur_ (_Q. pedunculata_) (the so-called French oak). The first two species are the most commonly used for wine ageing, while _Q. robur_ is very common for Brandy ageing and is less and less used in oenology due to its high ellagitannin content, its high oxygen permeability and its low release of aromatic compounds [4; 8; 9]. In many wine regions of the world, the use of new oak barrels (or barrels with a limited period of use) increased from the 1990s onwards due to the change that occurred favouring quality. This trend led to an increase in demand for new barrels, resulting in the need to explore new sources of quality cooperative wood [5; 10; 11; 12]. This gave rise to the exploitation of the same species (_Q.petraea_ and _Q.robur_), but from different origins, with different countries such as Spain, Hungary, Poland, Russia, Ukraine, Romania and Portugal entering the market. Many of these woods have been used for a long time but have been less studied and characterised. These oaks are of the same species as the \"French\" ones, but as the structure of the wood and the final chemical composition depend on other factors such as geographical origin and forest management treatments, it is important to study them. Studies of the woods of these species from these geographical origins showed similar characteristics to traditional American and French oaks, being suitable for contact with quality wines [3; 13; 14; 15; 16; 17; 18], and some even claim that these origins have intermediate characteristics between French and American oaks. With the introduction of these geographical origins, French oaks have been colloquially referred to as European oaks. On the other hand, the interest in giving wines their own or special personality has led to the proposal of alternative oaks to _Q. petraea_, _Q. robur_ and _Q. alba_ that can give certain differentiating notes that are positively valued by the consumer. In this context, a market opportunity has opened up for other nontraditional or alternative woods, namely oak species that have not been used in cooperage such as _Q. figinea_ [PERSON], _Q. pyrenaia_ [PERSON], _Q.