The use of oak plays a major role in winemaking and can have a profound effect on the resulting wine, affecting the colour, flavour, tannin profile and texture of the wine.
The species of oak typically used for American oak barrels is the 'Quercus alba' a white oak species that is characterized by its fast growth, wide grain and lower tannins. Found in most of the Eastern United States as well as Missouri, Minnesota and Wisconsin. In Oregon the 'Quercus garryana' white oak has started to gain usage due to its closer similarities to European barrels.
American oak tends to be more intensely flavoured than French oak with more sweet and vanilla overtones due to American oak having 2 to 4 times as many lactones.

 

Winemakers choose American oak typically for bold, powerful reds, base wines for 'assemblage', or for warm climate Chardonnays. Another major difference between American and French oak comes from the preparation of the wood. The tighter grain and less watertight nature of French oak allow coopers to split the wood along the grain, and then seasoned for 24 to 48 months in the open air.
Even though American coopers may use a kiln-dry method to season the oak, almost all others will season American oak in exactly the same way as French. Open air seasoning has the advantage of leaching undesirable chemical components and bitter tannins, mellowing the oak in a manner that kiln-dry methods are incapable of replicating.
Since French oak must be split, only 20-25% of the tree is utilized - American oak may be sawn, which makes it at least twice as economical. It's more pronounced oxidation and a quicker release of aromas help wines to lose their astringency and harshness faster; making it the oak of choice for shorter maturations; 6-10 months. Because of American oak's modest tannin contribution, the perfect first fill is a wine with abundant tannins and good texture; it allows the fruit to interact harmoniously with the wood, contributing to an array of complex aromas and soft, drinkable tannins.