In the first installment of our OakY series, we delved into the rare and sought-after Mizunara oak from Japan. Today, we’ll be venturing past the Pacific to the American industry and its unique rule of using only virgin oak for the maturation of certain whiskey categories. American whiskey, with bourbon at the helm, has been growing rapidly. The category now enjoys huge collectability and consumption, mostly within the US. Bourbon offers a very unique and distinctive palate, which separates it from other global categories. The reason why is largely due to the wood the whiskey matures in.

Starting with a definition, Virgin Oak means that the interior of the oak cask has never held had any alcoholic liquid. Ex-bourbon, ex-sherry, and others ex- barrels have previously held other liquid, the name of which follows the ex- term. Ex-sherry casks previously held sherry wine, were emptied, and then filled with whisky. Cognac, rum, even craft beer; distillers are getting more and more experimental when it comes to wood finishes.

But Virgin Oak is as pure a barrel as they come. By law, barrels in America must be newly charred and then filled with bourbon, rye, or other types of whiskey, before being allowed to age. This gives bourbon its unique sweet and vanilla-forward character and also adds a lot of color to the spirit, despite short maturation. Let’s delve deeper into these points.

Virgin oak’s benefit is that impacts the spirit quickly and with intensity. Each time a spirit is filled into the barrel and emptied out the interior of the oak grows “weaker” and imparts less flavor to the whiskey; it also takes much longer as the wood isn’t as pure and powerful. For this reason, the terms 1st fill or 2nd fill are used widely in Scotch, 1st fill casks are more premium as they’ve only been filled once, then it’s 2nd fill, refill, and so on. The fact that virgin oak barrels are filled for the first time means that the wood quickly imparts an abundance of flavor and color, making one think that the spirit has matured longer that it actually has. However, the downside of virgin oak is that, if not monitored closely, the wood’s impact on the whiskey can be too harsh and ultimately destroy the spirit. Maturation may be faster but also more unstable, so this is something American whiskey distillers must watch closely. The notes that come from virgin oak include toffee and strong vanilla notes as well as some subtle, fresh spice.

Beyond the US, many Irish, Scotch, and World whisky makers are also experimenting with finishes in virgin oak, in order to add a new category of flavor to their whiskies. By ageing whisky for only a short period in virgin oak, many of the wanted flavors come through without overwhelming the spirit. Scotch producers can then move the spirit back into a 1st fill or 2nd fill cask and let the spirit slowly mature.

Keep an eye out for any unusual virgin oak releases in order to experience something very unique. Alternatively, grab the nearest bourbon bottle and focus on those sweet, syrupy flavors that virgin oak helps bring out.

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