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In oak we trust


“Terrific Race, the Romans,” extolled an incarcerated Spike Milligan in Monty Python’s The life of Brian.

Apart from schools, sanitation and the aqueduct, they have provided us with many facets of our civilised lives, including the development of wine.

The Romans appreciated the effects of aging wines, using sulphur to reduce spoilage, and they understood the value of oak.

In particular, oak from the genus Quercus possesses characteristics that imparts flavour and structure in wine. In the past, cedar, palm wood and other oaks have been tested and used, but each have lost favour. The wood has to be supple enough to work with, strong enough to form a barrel, and must not taint the wine.

The most common origin of oak is either from the French forests of Alliers, Limousin, Troncais, Nevers and Voges or the American forests of the Eastern US.

The oak can be used at the fermentation phase, usually in Chardonnay and in the use of some old world techniques in making Riesling. In Chardonnay, French oak is dominant, and the infamous unoaked Chardonnay is on the decline after peaking earlier in the decade. I wonder why bother with unoaked varieties, as the correct oak exposure in fermentation can add layers of complexity, including hints of cinnamon and cloves.

Oak is not exclusive to Chardonnay. Sauvignon Blanc can have some oak exposure, in which case it is denominated Fume Blanc style. A great example of this is Cloudy Bay TeKoko. 

The most prolific use of oak is in ageing red wines. Oak reacts with wine to add phenols/lactones, which can be likened to vanilla and some tannins, to aid structure. The microscopic permeability of the wood allows small amounts of oxygen to react with the wine to soften it.

French oak usually is slow growing and has a tight grain which imparts more complex, savoury notes, while American oak, with its broader grain, adds strong sweet vanillin and coconut aromas.

French oak suits Cabernet Sauvignon, Pinot Noir, Merlot and cool climate Shiraz, while American oak adds the powerhouse hit to warm climate Shiraz wines, such as Penfold’s Grange. Oak ageing is avoided with most varieties of white wine, except Chardonnay.

Another variable can be the degree to which the barrel has been fired or toasted. This is a wine maker’s personal preference, but Pinot Noir is the most varied in toast effect.

Toasted barrels can add caramelised notes and hints of toffee. The oak has to be dried to mature the wood, and can be naturally dried between three to eight years, or dried by fire for a quick result.

Also at the wine makers discretion is the length of time left in oak. Modern day Pinot Noir is left between eight and 12 months, while for big reds like Grange it can be two or more years. Some Spanish reds, such as Rioja, can be left for eight years.

New or used oak and the size of the barrel add to this conundrum wrapped in an enigma. It all sounds a bit like the bloke in the corner store just wanting to buy milk that tastes like milk.

Oakey wines to try

2008 Cloudy Bay Te Koko Marlborough – while some noses are turned up knowing this is a Sauvignon Blanc, the exposure to eight months oak (10 per cent new oak) adds to the complex nose of white peaches and hints of lycee, but with a flowing nose of ginger and toasty oak. The palate is rich, with subtle creamy lemon curd minerality.

2010 St Andrews Clare Valley Chardonnay – fermented in French oak and aged for 10 months, this wine has white stone fruit aromas and hints of lime, marrying with nuttiness from the oak. There is a satisfying, well-rounded palate with a long finish.

2009 Elderton Barossa Shiraz – this has been aged in American oak for 14 months. Along with the black fruits and some hints of chocolate, the essence of vanilla is evident. Full-bodied and nicely balanced tannin and American oak.

2010 Cape Mentelle Shiraz – aged in French oak for 15 months (25 per cent new), the blackberry fruits and hints of spice and pepper are accentuated by the savoury effect of the French oak. The palate follows on from the bouquet in a pleasing, full-bodied cool climate Shiraz.