FAWQ: the use of oak in wine

What exactly is the purpose of oak in wine?

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I often see it mentioned on wine labels, and I’ve seen wine barrels made from it, but I don’t understand what it actually does. Is it just fancy storage?

Oak has been used extensively throughout winemaking history; in fermentation and maturation. Oak barrels are used to store wines, predominantly reds, and impart flavour characteristics into the wine during its maturation process.

A lot of wine today is made without any oak intervention, as there are many alternative fermentation vessels that can be used, such as stainless steel tanks, plastic tanks and cement. However oak still plays a vital role in the maturation of many wines, especially premium reds and Chardonnay-based white wines.

New oak barrels are incredibly expensive, and impart the most flavour characters into a wine. These are generally used for premium wines, due to the investment required.

As well as adding flavour, they add complexity and textural elements to a wine.

Once a barrel has been used, it can be reused several times across the years until it runs its course. As a barrel ages, it loses flavour intensity - imparting less of its characteristics into the wine, and in later years it is primarily used to add textural elements to a wine.

The two main types of oak used by the wine industry are French and American oak, which have striking differences in flavour, and can be identified in a wine with knowledge and practice.

There are two main types of oak used in the wine industry: American and French Oak. The difference between the two is striking, and you can learn to identify the characteristics of each type of oak while tasting the wine.

Terms you may have heard:

French Oak: This is the Rolls Royce of oak. Sourced from a number of different forests in France, French oak is used in some of the most expensive and complex wines in the world (think Burgundy and Bordeaux). This has tighter grain than American oak, so it takes longer to impart its characteristics upon a wine. It often comes across in wine as flavours and aromas of cedar, vanilla and spice characters. It also adds a textural element to the wine.

American Oak: American oak is by no means a poor cousin, but more of a flamboyantly dressed cowboy. It has a looser grain and is more ostentatious than French Oak. It imparts flavours on a wine in a shorter time, and can be very overwhelming when overused. Bourbon is aged in brand new American oak, and the flavours it gives to a wine are similar: coconut, sweetness and formic acid (crushed ants!). You've probably seen this oak in wines from Coonawarra, as well as some of the d'Arenberg range.

New Oak: This is exactly what it says it is - a barrel that has never been used to store a wine or spirit before. The coopers (barrel makers) will char the inside of a barrel, giving it a thin layer of charcoal. This is known as toasting. A lightly toasted barrel will impart generally milder flavours, and up through to medium and heavy toast, the flavours become more apparent. Wine that goes into a brand new oak barrel needs to be able to hold its own: it needs sufficient weight, fruit, tannin and acidity to withstand oak ageing. If a subpar wine is placed in new oak, it will come out tasting like oak juice.

Old Oak: Once a barrel has stored a wine, it is not discarded, but usually reused for lower level wines. This is due to barrels being very expensive, but also because as oak 'ages' it imparts less of its character upon a wine. This means that old oak barrels are used to add spice and some oak influence, but don't completely overwhelm a wine. Eventually though, barrels will become obsolete through use and can be retired to be used as garden, home or store decorations.

Seasoned Oak: A fancy back label word for old oak.

Hopefully this can help you decipher some of the back label information on the wine labels in your local store. Oak is the most important for red wines (especially Shiraz and Cabernet) and for delicious, delicious Chardonnay.