There is beer in these oak barrels, but these are not beer barrels. Very few breweries today employ coopers to craft their own. And, I don't believe that there are any American 'craft' breweries which do so.
More and more breweries, however, are re-purposing wood (usually oak) barrels which had been used, at some earlier point, to hold other alcoholic beverages, such as whiskey, rum, wine, etc. Especially bourbon barrels —fifty-three gallons apiece— each of which, by U.S. law, can only be used once to make bourbon (but no law as to how often a brewery can brew into them).
Re-use them after that, and there'll be diminishing returns from bourbon flavor, but increasing influences of flavor of the oak itself, and micro-oxygenation, maturation, or, possibly and often intentionally, 'wild' fermentation from resident or ambient yeast and bacteria.
The couple above was deep in conversation, at Wild Heaven Craft Beers, a production brewery in Avondale Estates, Georgia, a small city, just outside of Atlanta, as seen on 25 February 2016. Behind them were rows of (former) bourbon oak-barrels, now containing maturing beer. The brewery specializes in Belgian-style and, of course, barrel-aged beers.
- See more photos of Wild Heaven: here.
- More on bourbon barrel volume and dimensions: "How much bourbon would a bourbon maker make?".
- While a bourbon barrel is a real, physical thing, a beer barrel, however, is not an actual container. It is a unit of volume measure, equal to thirty-one U.S. gallons. A beer cask, on the other hand, is a real vessel, but is not a barrel! A firkin, for example, is a cask that contains 10.8 U.S. gallons of 'real ale,', that is, ale which is cask-conditioned: partially fermented in the cask, and unfiltered. More: here.
- Pic(k) of the Week: one in a weekly series of personal photos, usually posted on Saturdays, and often, but not always, with a good fermentable as the subject. Camera: Olympus Pen E-PL1.
- Commercial reproduction requires explicit permission, as per Creative Commons.
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