Oak and Wine

An oak is a tree or shrub in the genus Quercus-Latin "oak tree"), having 600 extant species. "Oak" may also appear in the names of species in related genera, notably Lithocarpus. The genus is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes.

Many woods have been used throughout the history of wine making. Over time, however, the favored wood for making barrels has become oak. There are three main sources of oak: France, Slovenia, and the United States. French and Slovenian oaks are different species than American oak, which provides one choice for the winemaker. Some winemakers chose oak from specific forests, since each has its own unique flavor characteristics and grain structure. Oak is the wood of choice for a variety of reasons. First, the forests in Europe are relatively close to the wine making regions that use barrels. Second, the flavor profile provided by oak is complementary to many wines. Oak is a source of vanillin, the flavor compound in vanilla. Third, oak has a grain structure that allows for controlled diffusion of air through the wood. This slow incorporation of air into aging wine aids in the development of mature characteristics. French and Slovenian oak has a very tight grain, and therefore the slowest diffusion of air. American oak is wide-grained and oxygen can play a much bigger role earlier in the aging process.