French oak forest area; see under oak wood.
Since antiquity, a wide variety of woods from the tree species acacia, eucalyptus, chestnut, cherry, palm, pine and cedar have been used to make wine barrels. Wooden barrels were hardly known in ancient Greece, but the Greek historian Herodotus (482-425 B.C.) reports of such barrels made of palm wood in the city of Babylon. It is considered fairly certain that the Celts were already using wooden barrels for transport two to a thousand years before the era, and that the Romans took over this craft from them. However, the most suitable wood for wine storage or barrique ageing is oak. It is one of the hardest woods, is tough, very durable and yet easy to work. In addition, the nature of the ring-shaped pores prevents liquids from passing through the wood. This is ideal for building all kinds of vessels, especially barrels.
Last but not least, oak wood has a natural affinity to wine. The French recognized this very early and have been using it for centuries for the barrel type Barrique created in Bordeaux. There are about 300 oak species worldwide, but only three white oak species belonging to the taxonomic genus Quercus are used for the wooden barrels. Two of them grow in Europe. These are the winter oak, holm oak or sessile oak (Quercus sessiliflora or petraea), and the summer oak or pedunculate oak (Quercus robur or pedunculata). The third is the American white oak (Quercus alba) with numerous species. Generally, the American oak produces more astringent and aromatic wines than the European one. For the sake of completeness, we should also mention the oak species Quercus suber, from the bark of which the corks come.
For the oak barrels, wood from trees that are at least 80 to 100 years old is used. After completion, they are subjected to toasting (barrel firing). There are three groups of wood phenols that are added to the wine during the barrique ageing process. The primary ones are directly leached, the secondary ones are formed chemically and microbially from the wood phenols and the third group consists of those which are formed by the decomposition of the oak wood component lignin. The most important of these aromatic substances are eugenols, furfurale, lactones, tannins, terpenes and vanillins. Fine-pored woods release these substances slowly and in small quantities and coarse-pored woods release them quickly and in larger quantities. In French, for example, the grain is expressed as "grain fin" for a fine-pored wood and "grain gros" for a coarse-pored wood.
Until the beginning of the 20th century, oak wood came mainly from Poland, Latvia and Estonia. Today the wood comes mainly from France and North America. The American oaks of the Quercus alba species grow mainly in the dry forests of eastern North America. The most important...