Does it make any difference? Well, taste it and see in an interesting matching pair of Hungarian Chardonnays from Thresher, Wine Rack and Bottoms Up. Cool Ridge Barrel-Aged Chardonnay (pounds 4.49) and 1994 Cool Ridge Barrel- Fermented Chardonnay (pounds 4.99) were both made by Australian Kym Milne from the same Chardonnay grapes, the best he could find in Hungary's Nagyrede region. Both wines - made in the same new oak barrels - are rich, ripe and oaky (and excellent value), but the barrel-fermented one is subtler and more delicious, with extra layers of flavour.
Barrel-fermented wines are always a little more expensive because of the fiddly labour involved in superintending a cellar-full of bubbling barrels, rather than one big stainless-steel vat. You'd expect a wine actually fermented in new wood - with all that heat and bubbling - to extract more flavour from the barrel, and taste more obviously woody. But winemakers have long observed that fermenting in small oak barrels makes for oaky flavours that are less blatant (and all the yummier for that), and more subtly blended in with the flavours of the wine itself. Barrel-fermented wines also tend to be paler and fresher than their tank- fermented mates, and to age better.
Researchers at Bordeaux University discovered that wine extracts from oak a range of aromatic substances, some of them naturally present in the wood, some of them created in the cooperage when the barrel staves are heated over open fires. There are smoky, spicy and caramel flavours and, above all, vanillin, which has a strong smell of - yes - vanilla. You can put five or six successive lots of wine into the same barrel before there's nothing left to extract, but the strongest flavours are shed into the first.
One reason barrel-fermented wines are more subtle, according to the Bordeaux boffins, is that the live, fermenting yeasts transform some of the substances extracted from the wood. They turn vanillin, for example, into gentler vanillyl alcohol. Live yeasts also absorb some of the other aromatic wood extracts.
Barrel-fermented whites are paler and able to age longer due to the tannins - the other main substances extracted by wine from oak barrels. These can taste bitter in excess and easily combine with oxygen, turning brown, darkening the wine and making it taste less fresh. But in barrel-fermented wines they are deactivated by substances (proteins and sugars) released by the yeasts.
White wines are the main candidates for barrel-fermenting. The method is less practical for reds which need to ferment with their colour-rich skins and tannin-rich pips. In Australia they sometimes part-ferment top- quality reds in a tank, remove the skins and pips when the fermenting wine is sufficiently coloured, and finish off the fermentation in the barrel. It only works with very ripe, dark, tannic grapes.
No one yet puts "barrel-fermented" on red wine labels, but keep your eyes skinned and tastebuds ready. "Barrel-fermented" now sells white wines so successfully that it can't be long before it spills over onto red labels, too.Reuse content