When you’re checking out a new wine you may read that it has been fermented or aged in oak… and you may be wondering what that even means, and how that will affect how the wine tastes?
The perfect match…?
For hundred of years oak has been used to ferment and store wine for practical reasons. But today, oak is still used in wine production because of the amazing texture, flavours and complexity that it can impart to wine. A stint of time in oak can simply transform a wine.
However, not all wines will benefit from time in oak. For wines where the style is intended to be fresh and fruity (whites in particular), the weighty flavours from oak can steal the show, and instead the winemaker may opt to ferment and age such wines in inert vessels, such as stainless steel or concrete.
The mighty oak
The desirable impact of oak on wine is mainly due to the composition of oak wood, as well as how the wine interacts with the oak vessel and the environment around it:
- Oak composition - oak wood is made up of different complex chemical compounds and one of the most important group of compounds for the purposes of wine are called ‘phenols’. These not only impart some tasty flavours, but one of the classes of phenols includes tannins, which can be super important for structure and textural complexity in wine.
- Wine’s interaction with the oak vessel - when stored in oak, wine can can extract all of those lovely tannins and flavours from the wood. Think toast, vanilla, smoke and cloves. Oak is also porous which means that not only water and alcohol evaporates outward, but small amounts of oxygen from outside can seep into the wine. This oxidation makes wine smoother, but (bonus) it also means delicious flavours such as toffee, fig, nut and coffee can develop.
When deciding to use oak for a wine a winemaker has quite a few options! There are a few important factors for them to consider:
- Oak species - there are about 300-odd species of oak, and each has different characteristics, particularly dependent on where it is grown. Most oak used for wine is one of two types - European (mainly French species Quercus robber and Quercus sessiliflora)) or American (mainly from the Midwest, Quercus alba). American oak tends to be heavier, denser, and less porous than European, and usually has less (but more harsh) tannins. It usually associated with pronounced vanilla and coconut-like flavours. European oak is more subtle in terms of flavour (think toast and nuttiness), but it is usually more tannic, and allows for greater oxidation of wine. Neither is better than the other, and so the idea is to find a type of oak that will best support the style of wine desired.
- Production and age of the vessel - a wine maker can opt to store wine in new barrels, used barrels, or a combination of the two. The impact of the oak will be strongest when new oak is used. The production of oak barrels involves heating the staves (small planks) so that they can be bent into shape, and this heating also transforms the chemical compounds in the oak including the tannins and flavours. The temperature and length of heat exposure (the level of ‘toasting’) therefore affects what flavours the oak will impart to the wine, and the impact of toasting will diminish each time the oak barrel is used. Not all wines can stand up to the intensity of the woody flavours imparted by new oak though, and similarly the flavours of new oak are not desirable for all wine styles, so many winemakers who use oak choose to use seasoned (previously used) barrels, or use new barrels for only a small portion of the wine, in order to make a final wine with more subtle oak flavours. The cost of new oak barrels also means that they are usually reserved for higher-quality wines that can usually support and integrate the new oak flavours and tannins better (but which can also fetch a higher price when sold).
- Size of vessel - with a larger surface area to wine ratio, small barrels (around 225 litres) will have a bigger impact on wine than larger oak vats (which can exceed 2,000 litres in size). This means smaller vessels impart lots more tannins and flavour, and again, this will be a consideration for the winemaker who may want to limit the impact of oak on the style of wine desired by using larger vessels.
Oak barrels do not come cheap, especially new ones, fresh from the Cooper (barrel maker). Oak is often the second biggest expense for a winery after salaries. This is why oak barrels are usually the reserve of more premium wines. But there are other options for the winemaker who still wants to achieve those oaky flavours and tannins for their wine.
Staves and chips, made from oak wood that’s unsuitable for barrels, can be used for a fraction of the cost and added directly to the wine (either loose or enclosed in a giant mesh teabag). Most staves and chips come toasted in a variety of ways and flavours, but the consensus is still very much that these alternatives can never achieve the same subtle and complex effects as those from oak barrels.
The future for oak?
The love affair between wine and oak is here to stay for sure. Top wines will still be aged for longer in oak and use a higher proportion of new wood than cheaper bottles. Though consumer tastes are changing, and there is a trend for more restrained and integrated styles of wine fermented and aged in oak.
If you want to steer clear of oak completely then you certainly have many options too, and it is interesting to see some wine styles that you may have previously associated with oak being made unoaked, and even specifically marketed as such. A great example is Chile’s Viña Echeverría’s Reserva Unwooded Chardonnay. Chilean Chardonnay will often invoke thoughts of creamy, oaky flavours, but this wine is made completely unoaked, and instead the focus is on its citrus and tropical aromas of pineapples, ripe melon and peach.
How oaky do you like your wine??
Remember to check out future blog posts and come back soon. You heard it first here on the Oh Grape Vine!