Vintner Views – August 2007

Wine Barrels 201

   In August, we covered the anatomy of a barrel, including the infamous bunghole.   We received some interesting feedback on more colorful applications of that term, but today we must forge on, as promised, to discuss further the whys and hows of oak aging.

   Barrels contribute oak flavor and tannins to the wine, adding complexity and body.  The types of flavors contributed range from mild vanilla and banana flavors, to coffee, toast and chocolate flavors.  The range of flavors contributed by a given barrel is largely determined by the toast level inside the barrel.  Cooperages, where barrels are made, will usually offer light, medium, medium-plus and heavy toasting of the inner surfaces of a barrel.  There are also options for toasting the heads of the barrel as well, providing a greater volume of that particular flavor.

   This toasting process occurs over a flame before the barrel is fully assembled.  The artisan coopers use an oak fire.  The mass production cooperages generally use a gas flame.  Once the barrel is toasted, the hoops are cinched up and pounded into place.  Once in the winery, the barrel just needs a quick soak and a rinse before it’s ready to hold wine.  Most barrels hold liquid without any special treatment.  As mentioned in the August article on barrels, the oak staves fit together nice and tight with the aid of steel hoops.  Problems holding wine usually arise only if the barrel sits empty in a dry environment.  Under this circumstance, the wood dries and shrinks, leaving cracks that can leak rapidly.  Although it’s rare for a new barrel to leak, sometimes there is a grain irregularity, a knot or some other minor flaw that can cause a major loss.  Luckily, the cooper or barrel master has a pretty extensive quiver of techniques to fix a “leaker”.

   One technique involves garlic and chalk.  First the wine must be removed from the barrel.  Then, using a clove of fresh garlic, the barrel master rubs the garlic clove on the barrel, squeezing the juice and pulp into the problem area.  Then a piece of chalk is rubbed into the same spot.  Somehow the combination of the two makes a pretty good seal, as this usually stops the leak.  Stranger than fiction by most accounts.

   Not all wines benefit from oak aging.  We make white wines without it about half the time or more.  Unoaked Chardonnays have recently become just as popular as their oaked counterparts.  On the other hand, most red wines benefit from some time in the barrels.  Red wines are heavier and rougher in their youth.  They need time to mellow, and the oak helps that to happen.

   As mentioned, barrel aging can add flavor to the wine in the form of oak tannins, and toasted oak flavors.  However, this only happens early in the life cycle of the barrel.  A new barrel contributes much more flavor than a one year old barrel.  This is because the flavor comes from the inner surface of the barrel and as the flavors are leached from the wood, it becomes increasingly more difficult to get flavor from the deeper levels of the wood.  Let’s call it peak flavor extraction.  Over the course of three or four years of constant use, all perceptible flavor has been extracted from the barrel.

   The good news is that there are ways of getting fresh flavor out of an old barrel.  The most common and economical way of doing this is to remove one of the heads for access and insert a matrix of thin oaken staves, toasted just like the original staves, and attached to the inside of the barrel.  These “inner staves” are about a quarter of an inch thick and attached to one another with stainless fasteners and Teflon tubing.  The cooper then reassembles the head, pounds on the hoops, and you’ve got roughly another year or two of oak flavor in the same container without replacing the barrel.

   The other way to get new flavor from an old barrel is to open up the barrel, shave off a thin layer of wood from each of the staves, and toast the freshly exposed oak again.  Obviously you can’t do this too many times or the strength of the barrel eventually becomes compromised.

   Next month we’ll wrap up our discussions of the oak barrel and the role it plays in modern winemaking.  Until then, keep your glass at least half full, put your back to the wind, and if you’re a winemaker, keep your bungholes clean!

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