What exactly happens when you put Oak Master closures in Beer?
Oak is full of many flavorful and aromatic compounds and chemicals that, when added to beer, create another level of depth and complexity. Examples are furfural, which lends caramel sweetness, or eugenol, which is clove-like. Vanillin, the most recognizable flavor, tastes and smells like vanilla. Lipids, which constitutes the oils, fats and waxes found in the wood, are responsible for oak lactones, which lend coconut and aromatic wood flavors.
These are the basic flavors found in all types of oak, and the ones we as brewers are looking for. The important thing to think about when choosing oak for your beer is, how will these flavors interact with the flavors already present? Knowing which type of oak contributes which flavors is the key in matching beer to wood.
The three most common types of oak are American, French, each with its own balance of flavor and complexity. American oak has a great aromatic sweetness along with a nice vanilla component. It provides a sweet and full mouthfeel to beer, easily paired with most malt combinations. French oak also has an aromatic sweetness as well as providing a full mouthfeel, along with cinnamon and allspice characters. It is widely praised for its sweet spice and confectionary flavor compounds (custard, butterscotch, milk chocolate).
The flavor profile of oak is enhanced during the toasting process, which compounds come out in what ratios depends largely on the variety of oak and the level of toast it received, ranging from light and untoasted to dark and heavy. When the oak is toasted, the characteristics unique to that variety are brought out and defined. American oak has a great aromatic sweetness along with a nice vanilla component. It provides a sweet and full mouthfeel to beer, easily paired with most malt combinations. French oak also has an aromatic sweetness as well as providing a full mouthfeel, along with cinnamon and allspice characters. It is widely praised for its sweet spice and confectionary flavor compounds (custard, butterscotch, milk chocolate).