The magic of oak

By Robin Ransom

Wooden containers have been used for storage and transport of wine for over 2500 years. According to Herodotus writing around 450 BC, Armenian merchants shipped wine in hollowed out palm-wood casks down the Tigris River to Babylon in the 7th Century BC. Constructing barrels from staves was a Celtic invention around 350 BC. The Celts in central and western Europe used them for transporting wine and a range of other goods. Julius Caesar noted their use during his campaigns in France in the 50s BC.

Many different tree species have been used for barrels over the centuries – acacia, cypress, chestnut, ash, pine and poplar, but oak came to be the main wood used for storing and ageing wine. In addition to being more watertight than most, it is also strong and physically easy to work. More importantly, oak seems to have a natural affinity with wine, not only in terms of the flavours it imparts but also because it actively helps clarify and stabilise wine. It also adds very useful wood tannins which help preserve and give body and mouthfeel to wine. In addition, wine in barrels is softened by gentle oxidation which occurs when oxygen moves through the barrel staves. Along with subtle chemical reactions between wine and oak, which are not yet fully understood, all these effects introduce layers of complexity into a wine which storage and ageing in inert containers such as pottery, glass, concrete and stainless steel cannot give.

For these reasons oak barrels are very much in demand amongst winegrowers around the world for fermenting, storing and ageing wine. Three species of oak are suitable for wine – one native American quercus alba and two Europeans quercus robur and quercus sessiliflora. European oak has been favoured by many winegrowers because it tends to have a more subtle effect on wine, whereas American oak is more obvious both in the flavours and the tannins it imparts. In recent years, improved cooperage techniques have helped reduce the aggressive flavour characteristics of American oak to some extent.

There is no chance we will run out of oak. Global oak resources are vast and in many countries, especially the US and France which have the largest acreages of oak, along with Russia and the Ukraine, the forests are managed in a sustainable manner.

The challenge for winemakers is to use oak barrels in a judicious manner. It is easy to over-oak wines by using too many new barrels. This has been done with chardonnay in new-world winegrowing countries, which seems to be the main reason why this wonderful wine has fallen out of favour with many. Over-oaked red wines are also common.

While oaky flavour will integrate to some extent over time, a young red which tastes like wood and not much else has little chance of emerging as a balanced, harmonious wine.

When used carefully oak barrels can contribute to wine a particular magic that helps lift a pleasant fruity fermented beverage to a sublime nectar which, when consumed with care, is capable of making the spirit soar.

Published 15 February 2012