Definition - What does American Oak mean?
American Oak is one of three main oak types used for making wine barrels. The species, Quercus Alba, is a white oak grown in the eastern states of Virginia, Missouri, Kentucky, Oregon, Ohio, Minnesota and Wisconsin, as well as in California. American Oak imparts strong, tough flavors into wines, which is why it is most commonly used to age the tougher reds, like Cabernet Sauvignon, Merlot and Zinfandel. It is rarely used for white wines.
WineFrog explains American Oak
American oak is a cheaper, more affordable alternative to the traditional French Oak used in winemaking, or the new, Eastern European Oak that became more prominent on the market in the 21st century. It is looser grained, but denser than both French and Eastern European Oak, which means it can be sawn instead of hand split. This reduces the amount of labor and expense required to create the barrels.
American oak contains more vanillin compounds than its cousins from across the pond. It imparts obvious, strong, sweet aromas and flavors, with common descriptors including: cream soda, oaky, vanilla, coconut, sweet spices and dill. Many winemakers avoid it though, because American oak is more aggressive and overpowering - the mouthfeel is very creamy and the aromas are immediately apparent. However, when used with the clean, fruit-forward New World wines, it can add a necessary amount of ruggedness. Unfortunately, American oak barrels tend to fade quickly, being unable to serve for multiple vintages of wine, as the tradition of oak aging requires.
Whether the winemaker uses American oak or another variety of oak depends on their desired end result. Some winemakers use a combination of two or three oak types, making for a more complex and layered wine. Also, American coopers (barrel makers) are working to improve the effects of American oak - softening the overpowering flavors and increasing the effectiveness of the wood. The reputation of a cooper America is more important than the origin of the wood - since the oak doesn’t change from forest to forest, consistency in barrel construction is critical for winemakers.