Monday, September 25 2017 4:09

I Would Have Been a Cooper…

Written by Dan Popernack, La Cabra Brewing

The magic when beer is aged in barrels.

In another life, I would have been a cooper—you know, a cask and barrel maker.

That’s because even the relatively basic maintenance we perform on the barrels in our brewhouse is enough to inspire me with appreciation for the craft of barrel construction.

The slow, patient work of bending nature into a watertight vessel that develops through years of use remains a mystery to most. But now that breweries large and small are expanding their offerings of beer aged in oak, this is prime time for beer fans to get some basic knowledge about barrels and how they’re used.

And, as with most beer questions, there’s often a short answer and a very, very long answer.

Well, here’s the medium answer for those who have ever wondered what those stacks of wood are doing hidden among the stainless steel tanks at your local brewery. And for those who’ve wondered how barrel aging produces beers described as big, bold, complex and unforgettable.

Thousands of Years in Under a Hundred Words

Oak has been used for millennia to transport dry goods and liquids, including beer. Tales of Catherine the Great requesting British Imperial Stout brewed strong enough to make the trek to Russia, German lager slumbering inside cool mountain caves, and the extra hopping required to get IPAs to British colonial soldiers are all well entrenched in beer lore. And for some American history, before Prohibition beer was not found in stainless steel tanks.

The unsung hero in these stories is the humble vessel: the barrel.

Which Wood, Which Use?

In the world of wood barrels, oak is the tree of choice. American, French and Eastern European oak are the three largest families in widespread use for barrels but trees grown to the rigorous specifications of coopers come from many regions. Some countries (France in particular) have forests protected by law solely for producing oak designated for barrel making.

As you might expect, different regions produce oak of drastically different character. In a very general sense, American oak tends to be sharper and brasher, while European oak is richer and deeper—that’s generalizing very broadly. The brewer selects the type of oak, accordingly, depending on the desired flavor to impart to the beer—vanilla, spice, smoke, musk, tea, coconut, tannin, floral, fruity or any of the myriad flavors of oak.

Another barrel fact: America’s bourbon frenzy results in about a million spent barrels each year, since the law requires new, charred oak barrels for making bourbon. Finding uses for those excess barrels has inspired many a brewer, including those at Goose Island Beer Company, credited with the first barrel-aged beer—Bourbon County Brand Stout in 1992.

For those not satisfied with this simplification of the complex science of oak rearing, Wood and Beer is an approachable and informative book for casual and intense beer fans alike.

To Bubble or To Sleep?

The two primary uses of wooden vessels are for fermentation (bubble) and conditioning (sleep) of beer. Primary fermentation can be sparked by the brewer pitching fresh yeast into the wort (unfermented beer) or spontaneous fermentation using yeast and bacteria living inside the barrel wood.

Fermentation in barrels rather than stainless steel provides modern brewers a powerful tool: fermenter dynamics. Without getting too deep into the topic, certain ale strains benefit from fermentation in shallow, wide vessels rather than tall towers of steel. For much of brewing’s history, fermentation would have occurred in relatively stubby tanks, so a barrel is a fitting vessel for these rustic yeast strains.

For example, for Belgian lambic the wort is pumped from the brewhouse into coolships (think giant swimming pool of beer!) to be cooled and inoculated by wild yeasts in the air. Then it’s transferred into barrels for fermentation and aging.

Developing True Barrel Character

Prolonged aging and conditioning of beer in barrels post-fermentation is where true barrel character shines—the smooth, full-flavored complexity. In the case of “clean” beers with no wild yeasts or bacteria involved, the beer picks up nuanced flavors from the wood itself as well as notes of whatever lived in the barrel previously—wine, spirits, coffee, whatever.

The challenge for brewers is preparing a beer that will both complement and be enhanced by the character of the barrel and the previous liquid. Barrels holding everything from maple syrup to hot sauce can be used, so balancing punchy flavors and making them meld with the beer is both art and science. Careful recipe development and blending different barrel projects together are key, and when executed well, can push beer to a different level of complexity.

Aging beer in a whiskey barrel is relatively straightforward: contact time between the beer and the barrel’s liquor and oak happens fairly quickly, and longer aging will soften and meld the flavors. But, in the case of “wild” beer—with earthy characteristics—the oak and spirit character of the barrel are amplified by the existence of bacteria and yeast that put the beer through a secondary fermentation.

With wild or funky barrels, the barrel is a living vessel that continues to develop and morph the beer as compounds produced during brewing and fermentation are consumed slowly by the organisms in the oak. These projects can rest for a few months to years as the beer develops.

While “clean” barrel aging is very intensely focused on the recipe and marrying the beer to the barrel, wild barrels require the brewer to let projects drift and give the critters in the oak time to do their magic. To add more factors to the process, in our own cellar, we’ve also seen beers change dramatically through seemingly small external variations, like fluctuations in humidity and temperatures.

From there, the brewer changes hats and becomes a blender—a practice that looks more like wine-making as the brewer/blender must select the correct barrels and flavors to achieve the desired result.

How Big Can You Go?

As you can tell, there’s a tremendous amount involved—just about oak—even before you get to the technical side of barrel construction. From tiny boutique barrels to 100 BBL foudres (3,100 gallons), breweries are constantly expanding their oaken flotillas and using new techniques to produce beers of singular character.

So, next time you see one of those bearded guys or … well, likely not bearded gals, but still identifiable … kicking around the brewhouse, ask them about their barrel projects. Then watch how passionately they care for these ancient beauties.


A former Spanish and English teacher who began brewing beer in the garage of his Malvern home, Dan Popernack opened La Cabra (Spanish for the goat) last year to meet the needs of his growing fan base. The seven-barrel, two-story brewpub and restaurant across from the Berwyn train station has gathered accolades from the likes of Craig LaBan (“impressive take on lambic”) and Philly Mag (2017 Best Brewpub, ‘Burbs). 642 Lancaster Ave., Berwyn.

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