There are
two uses of oak in the field of wine, one is the cork which is used as a
stopper and harvested from the bark of the Quercus suber every nine years. The other is the oak used to make wine
barrels.
The great French oak forests such as Nevers, Limousin and Tronçais were first used by Napoleon for
ship building purposes. Although very good for making ships, English oak is too
dense for making wine barrels. The oak
from warmer climates better allows the wines to breathe in the barrels.
Barrels made
by coopers are used for the storage and maturation of wine, beers, whisky and
vinegars. The wood can affect the flavour of wine and adds tannins. If the wine
can breathe this softens and develops the flavours.
In Bordeaux
the size of the barrel is 220 litres which gives a large surface area of wine
in contact with the wood. Only the best
and most expensive Chateaux can afford to use new oak each year. The used barrels
will be sold on to lesser chateaux after two years.
French oak
barrels are made by taking split wood which has been seasoned outdoors and then
constructing the staves into a barrel over a fire. A metal hoop is then forced over the barrel
which contracts when cool to hold the staves together and makes a watertight
container.
In America,
for wine and bourbon casks, the wood is not seasoned outside. It is kiln dried and sawn instead of being
split. This gives softer tannins and a
much more oaky vanilla taste to wine stored in them, such as Rioja. Many Scotch whisky distilleries will have
barrels made that are given to Sherry producers to use for a few years. They then get them back to store whisky in giving
the whisky its colour. Cognac aged by the docks in London ( a cool damp area )
takes on less colour from the wood hence the term very superior old pale .
In Cognac
the spirit is aged in Limousin oak.
Poor soil in the Limousin forest results in wood
that is at the far end of the scale in terms of looseness of grain. The release
of flavours in such wood is too aggressive for wine , but makes it ideal for spirits. As it rests
in the barrels there is an evaporation called ‘the Angels share,’ without this
the spirit would be too harsh as it softens it.
