French vs American Oak: What Each One Does to Wine

American oak makes wine sweeter and louder — coconut, vanilla, dill, caramel — because it is far richer in an aroma compound called oak lactone. French oak is quieter and firmer: cedar, clove, toasted spice, and more grip, because it is tighter-grained and carries more wood tannin.

The reason behind that has almost nothing to do with national character and everything to do with how a tree is cut, dried and burnt. Know the mechanism and you can predict what a barrel will do before you taste it.

The real difference is made in the sawmill

French barrels come from Quercus petraea — sessile oak, the prized one — and Quercus robur, out of forests such as Tronçais, Allier and the Vosges. American barrels come from Quercus alba: faster-growing, wider-grained, lower in wood tannin.

Here is the fact that explains the price, and it is a plumbing problem. Both trees grow tyloses — balloon-like cell growths that bung up the vessels the living tree moved water through. Q. alba grows them so densely that a stave cut straight across the grain still holds liquid, so American oak can simply be sawn. European oak plugs its vessels far more sparsely, and a sawn European stave weeps. It has to be split along the medullary rays instead, which throws away everything that does not lie true to the grain: coopers reckon on a fifth to a quarter of a French log becoming staves, against roughly double that for American. Most of what you pay for in a French barrique is the three-quarters of the tree that never became a stave.

Staves are then seasoned outdoors for 24 to 36 months. Kiln-drying is quicker and softens the wood’s tannins far less well.

Side by side

How to taste it this week

Buy a traditional Rioja Reserva and a Left Bank Bordeaux, and open them together. Reserva rules demand at least 12 months in 225-litre barrels, and the traditional houses fill them with American oak — so the wine comes pre-labelled for the experiment.

Smell both before they warm up. The Rioja gives coconut, sweet vanilla and often a green, dill-pickle edge over Tempranillo’s red cherry. The Bordeaux gives cedar and clove, and its tannins feel tighter on the gums. Watch the temperature: too warm and the vanilla turns syrupy. The same test works in white — a cheap Californian Chardonnay against a white Burgundy.

What most guides get wrong

Origin is not destiny. Three things routinely overrule it.

• Toast beats country. Fire degrades the coconut compound, so the heavier the char the less of it survives — in American wood as much as French. A dark-toasted American barrel can read as less “American” than a pale-toasted French one: mocha and smoke where you expected coconut.
• The cooper matters as much as the forest. Rioja’s bodegas buy American oak as sawn planks and have it coopered in Spain, seasoned in the open air for a couple of years rather than kiln-dried the way a bourbon cooperage would. Same species, gentler handling, and lightly toasted rather than charred — which is why traditional Rioja smells of vanilla and not of bourbon.
• Most barrels say nothing. After three to five vintages the oak flavours have largely leached out. “Neutral oak” is a container, not a seasoning.

Below a certain price no barrel was involved at all. The EU only legalised oak chips in October 2006, and the same rules bar those wines from saying “barrel aged” on the label — so on a cheap bottle, the absence of that phrase next to obvious oak flavour is itself the tell.

Which one I would actually buy

For Tempranillo, Zinfandel and warm-climate Shiraz, American oak — and I would take a traditional Rioja Reserva over its modern French-oak sibling nine times in ten. The sweetness has somewhere to go in those wines. For Cabernet, Pinot Noir and Chardonnay, French, without much argument: those grapes are built on texture, and American vanilla sits on top of them rather than inside.

The wine to avoid is the cheap one that shouts coconut. American oak flavour is the easiest thing in winemaking to fake, so on a thin red it reads as sweet sawdust. If the oak is the loudest thing in the glass, the wine underneath rarely justifies the wood.

Winelingo can scan a label and tell you the style and region behind it — the starting point for working out what the barrel was doing.