Flavors, aromas, and tannin imparted by American oak add a richness and depth to wine and spirits aged in barrels. The unique expression of American oak you taste in your glass is a product of two main influencers: the trees that produced the barrels and the level of barrel toast. Winemakers and distillers are increasingly experimenting with American oak barrels from different regions due to their signature flavor profiles.
The Influence of Oak
Flavors and aromas are impacted by the tree itself: where it was grown, the composition of the hardwood, the tightness of the grain. Tighter grain is less porous, leading to a more subtle oak flavor influence. Trees grown in cold, harsh climates produce typically wood with the tightest grain.
Due to the porous nature of wood, all oak barrels also allow for oxygen exchange, which softens the astringent character of a wine as it ages. The smaller the barrel, the more oxygen that comes into contact with the wine.
Tightest grain and fewer tannins, less oak impact.
Medium grain, big flavors of vanilla, lemon custard and spice, highest oak impact.
Tight grain, coconut and vanilla, less oak impact.
Medium grain, vanilla and spice, more oak impact.
The Perfect Toast
Toasting has a profound influence on flavor and aroma compounds. The process of applying fire to the inside of a barrel modifies the structure and chemical properties of the oak – like cellulose and lactones – diminishing fresh oak aromas and softening tannins while increasing caramel and vanilla character.
Even a few extra minutes over an open fire can change a barrel’s flavor and aroma profile. Lightly toasted oak exhibits spiced flavors, like cloves, cinnamon and nutmeg. Further toasting brings out vanilla, caramel and nutty aromas. Wines develop a smoky or butterscotch taste when they are aged in heavily toasted barrels. Such barrels are typically reserved for spirits like bourbon and scotch.