Oak has a vital role to play for the vast majority of wine producers. It can help tame the astringent elements of young wine and help provide structure and longevity. Colour, flavour, tannin and the texture of wine can all be influenced by the use of oak.
Oak is water tight, yet it is porous, so it allows the wine to breath, so much so that a proportion of water and alcohol will evaporate out of the cask and help concentrate and further harmonise the remaining contents. Oxygen passing into the wine helps to soften tannins, improving those bitter, dry characteristics.
France and America are the two main origins of oak used in the wine industry. In Italy, Slovenian oak is a popular choice. The price of oak can vary greatly, with French generally fetching a higher price. Certain forests in France, such as Limousin, may attract more than US$900 per barrel.
American Oak has wider grains and will impart a more ‘oaky’ taste with hints of vanilla. You’ll find a lot of Australian winemakers use American oak to bring secondary flavours to their powerful reds. It is also the oak of choice in Spain. French oak has a tighter grain and whilst being less oaky, it contains more tannins and has a more complex flavour profile.
Toasting is used by a cooper (barrel maker) to bend the wood into shape. The toasted side of the panels will face inwards, becoming in contact with the wine. On heavily toasted wood, the wine might acquire a caramelised flavour. Light toasting should impart a more restrained nutty smokiness.
This is where the skill and experience of the winemaker comes into play. What type of oak to use and how long to age the wine for. Whether to use new oak barrels, old barrels or even oak staves. Everything from the size and type of barrel to the time in barrel. Inevitably, final price will also be affected.