The majority of white wines in South Africa are treated in oak barrels in order to create a woody taste to the wine. This practice has a long tradition, going back to European wine makers, and is used to give what may otherwise be a delicate or flavourless wine a greater intensity of taste. The oak barrels are supposed to provide a nutty or buttery taste to the wine that bring out the floral elements and any additional spices. In the modern age, most wines produced in South Africa have these woody elements included as part of the background notes, and some drinkers may not even realise where the oaky taste is coming from.
The use of these oak barrels can have a significant influence on the wine, affecting not only the taste, but also the colour and amount of tannins in the wine. Some wine makers prefer to bring the oak to the wine, rather than having the liquid ferment in barrels, and so they will add oak chips or sticks to the wine. These chips can often be burnt, or coated with another essence, in order to add a smoked or toasted flavour to the wines. The use of oak chips in this fashion has allowed wine makers greater flexibility in the manufacture of white wine.
However, oak barrels are important for the process of turning grape juice into wine. Evaporation through the permeable membrane of the oak allows the wine to concentrate flavour and aroma, and oxygen passing into the barrel can soften the tannins, making them more velvety and pleasant on the tongue. The vanilla or tea flavour appears through phenols in the oak, and other degrees of toast can be gained by leaving the wine in older barrels. Newer barrels will give much more of a fresh-wood taste.
South African wines are often matured in these barrels for a year and a half to two years, although some of the red wines and Muscadel can be kept for up to five years before they are removed from the barrels. This length of time helps to mature the wine, so that it is ready to drink. However, white wines are different, and some may only have to spend a few months in the barrel in order to get the full benefit of the wine, before being sold on the domestic market. Younger wines can be less than a year between harvest and appearing on the shelves, but stronger white wines will probably have been matured for a year or two prior to bottling.
Most of the white wines in South Africa will have been wooded, or aged in oak barrels. Unwooded wines are easily found, and white wine blends will often have one or two wines which have been previously aged in wood. Only the newest of South African wine makers will have the option of using stainless steel tanks to mature their wines, and even then oak chips will often be added. The wood gives the wine an extra flavour and taste, so most drinkers appreciate the effort of adding oak to the wine.