Oak is a major component in the creation of wine. Its uses range from being just a storage container, through to adding specific characteristics to the finished product. The smaller the vessel, the greater amount of oak influence due to more surface area compared to the volume of wine within. Various forms are used including barriques (224 litres, commonly used in France and New Zealand), hogsheads (300 litres, often used in Australia) or puncheons (500 litres). And there are also the ubiquitous oak chips and a few other alternatives.
While Chardonnay has been at the centre of the ‘for and against’ argument, there is no doubt that some of the world’s finest examples are made using oak. Chardonnay labeled ‘Unoaked’ does offer the consumer a more straight forward, fruit-driven, easy quaffing style, but is unlikely to be of significant quality (or price).
There is some medium ground for the use of oak when making good Chardonnay. Whereas many Australian and New Zealand examples used to be heavily criticised for too much oak flavour (some still are), to use no oak at all seems so extreme, like saying you can have black or white, but not grey. The goal for winemakers today is to use oak to complement the fruit, rather than dominate it, to create a wine that has flavour, complexity and structure – but all in balance. I have seen or heard the expression ‘lightly oaked’ which I guess gives the consumer an indication – a bit like ‘mild, medium or hot’ on a jar of curry sauce. But this seems to be too clumsy somehow, too elementary.
The winemaker has a number of decisions to make when choosing his or her barrels. While French oak is preferred to American oak by many (even producers in the U.S.) it is more expensive. But its finer, tighter, more subtle influence remains in high demand. If buying French oak, there are a number of different forests that it can be sourced from. Some, namely Troncais and Alliers in the central region, are very popular, producing tight-grained wood for the highest quality barrels.
Once the staves are cut, the wood is ‘seasoned’ by being left outside for about a year. Only after this are they formed into barrels – usually over a fire, or steam or some other heating method to assist with flexing of the wood. The fire also provides the toasting effect and here is another decision, does the winemaker want light, medium of heavy toast levels? And then there are the heads; the round discs of wood at each end of the barrel – are they to be toasted too, and if so, at what level?
New oak is exactly that – new. In other words it can only be used once. At about $NZ1400 a barrique – that’s expensive and is one of the major contributing factors to the cost of producing quality wine.
The barrel once filled with wine and ensuring no air is present, has a bung inserted and is rolled so the bung sits at about two o’clock. This ensures that the closure is covered by wine and cannot let air in. While oak is naturally porous and a small amount of the content does evaporate, rather than ‘topping up’ barrels, with fresh wine kept especially for the purpose, many now believe that it is better to just leave it. Each time the bung is removed; air comes into contact with the wine and may cause bacterial problems. Left untouched, while there will be a small pocket that forms as the wine evaporates; this is merely water vapour with almost no oxygen.