One of the biggest influences on the flavour of wine is whether it has been matured, or even just stored, in oak. There are people who are prejudiced against oaked wine and will complain of even the slightest hint of oak, but many experts agree that if a wine has been carefully oaked it does not taste of wood, but more like a wine that has had its flavour subtly enhanced.
Oak aging of wine occurs when the wine has been fermented and/or aged in oak casks so that the flavour of the surrounding wood infuses some of its woodiness into the liquid. The resulting wine will usually taste richer, with creamy vanilla undertones and sometimes a little woody or even sawdusty. The oak is a type of seasoning for wine and getting the optimum level of oaky flavour is vital if a wine is to taste good at the end. Oak aging usually takes place in small oak barrels that hold 225 litres, being replaced every two or three years as newer barrels give the best flavour.
Oak is considered to be the most ideal wood for this aging as it not only has superb watertight qualities but gives the right sort of flavours,aromas and textures to enhance the wine. But there are different types of oak that offer certain distinctive flavourings. The most commonly used are the highly-prized, tightly-grained French oak which gives a subtle hint of oakiness, whilst American oak gives a more obvious vanilla character to the wine. Consequently wines that are more powerful in flavour tend to be stored in American oak such as Rioja, North and South American and Australian varieties. Other factors that allow oak aging to affect a wine’s taste are the size of the barrels, (larger ones giving less flavour), the age of the wood used, the actual time the wine spends within the cask, and whether the barrels have been toasted (i.e. lightly burned on the inside).
Now the fashion is for lightly oaked wines and winemakers are producing more subtle, elegant flavours. Red wines are often aged in oak, which add the required extra body and richness, with hints of wood-spice, cream and tannin. Soft light reds such as Beaujolais are typically unoaked, but the richer more powerful styles such as fine red Bordeaux or Californian Cabernet Sauvignon are almost always aged in oak. Similarly Rioja is oak aged for a long time to give it a distinct mellow creaminess. Port and Madeira are wood-aged and have an obvious hint of oak, whilst even some Champagnes are aged for a short time in oak barrels, although they never taste very oaky, just a bit more full-bodied. Some premium sweet white wines are also oak aged.