How Does the Barrel Type Affect the Flavour of a Wine?

Listen to someone describe the flavour of a wine and you might hear descriptions of the wine as “woody” or “smoky,” hints that might have come not from the grape itself but from the barrel in which the wine was stored as it aged. In fact, the barrel — and the different types of barrel available — can have an important influence on the flavour of the wine in a range of different ways.

The degree to which the barrel will affect the wine depends on the type of barrel used, how the wood was treated and how much the inside of the barrel was toasted before it was used. A barrel that has been heavily toasted, for example, tends to produce wines with stronger suggestions of smoke and spice. Those spice flavours aren’t added artificially; they’re present naturally in the wood and are imparted into the wine as it ages.

The flavouring happens as the phenols in the wood — chemical compounds similar to alcohol — interact with the wine. The result also depends on the grape but over time, a red wine should begin to accept undertones of mocha and coffee, while white ones can enjoy hints of cream, smoke, spice, vanilla and all those other subtle tones that are difficult to describe but which make wine-drinking so enjoyable.

If the wine isn’t just aged in the barrel but also fermented in it, then the activity of the yeast will make those flavours even more pronounced. The age of the barrel itself can have some influence too but even when vintners use so-called “neutral” barrels — casks that are perhaps four years old — the wood can still help to add a richer or creamer texture to the wine.

Barrels may also affect the colour of the wine, with white wines that have matured in oak barrels becoming a little darker. When those white wines are also fermented in oak barrels, the result can be a paler wine with a silken texture.

Of course, the type of wood used in the barrel is also important. Wine barrels can be made of chestnut, pine, redwood or acacia but the wood most commonly used is oak. (Acacia can turn wine a little yellow; chestnut has to be coated with paraffin; and redwood is difficult to bend into barrels.)