These Brewers Are Fermenting Beer in Giant Concrete Eggs

January 15, 2019

By Tina Caputo, January 15, 2019

Walk into just about any modern brewery and you’re sure to see rows of fermentation tanks gleaming in their stainless steel glory. But if you traveled back in time to the 19th century, you’d almost certainly find large vats made, not out of steel, but concrete. With the invention of stainless steel—a material that was easy to sanitize and would never rust—in 1913, concrete fell out of favor with modern brewers. It wasn’t until early-2000 that concrete was rediscovered as a fermentation and aging vessel, with winemakers, not brewers, leading the charge.

Steve Rosenblatt, founder of Sonoma Cast Stone, a California-based manufacturer of concrete tanks, says brewers are experimenting with concrete as a way to innovate and create distinctive new beers. “The interest started with sours, ambers and dark beers, but brewers have found even more distinction with lagers and IPAs,” he says. “There does seem to be a considerable distinction over brews fermented in stainless steel and even wood.”

The porous quality of concrete makes the tanks “breathable,” like barrels, but doesn’t impart oaky aromas and flavors to the liquid inside. Concrete is also a natural insulator, which means it stabilizes the temperature of whatever is inside of it. This allows for gradual fermentation, without heat spikes. And unlike concrete vats of old, the new models can include embedded temperature control systems.

Ben Neidhart, head brewer and owner at OEC Brewing in Oxford, Connecticut, has been using concrete since 2014, when he added a rectangular, open-top concrete fermenter to OEC’s array of vessels, which also include barrels, granite tanks, clay amphorae as well as a coolship. “The thing about different materials is that they have different porosities,” he says. The amount of oxygen that comes into contact with the beer can have a noticeable impact on its character.

Neidhart will sometimes make the same beer in different vessels to compare the results, or blend beers that were fermented in both concrete and stainless steel. OEC uses the concrete tank for Amara grodziskie, a beer style from Poland that’s made using oak-smoked wheat malt. “It’s a smoky beer, and the concrete introduces an interesting minerality to counterbalance the smoke,” Neidhart says. “I think it gives the beer a unique depth compared to the other fermenters that we have.”

The shape of the vessel is also important. “The shapes influence the yeast in different ways,” Neidhart says. “It really depends on the width to height ratio, because if you have those tall conical tanks, the weight of the liquid puts pressure and stress on the yeast. If you have a wider and shorter vessel, like a rectangular concrete tank, it puts less stress on the yeast because of gravity.” The less pressure on the yeast, the higher the production of esters, the compounds responsible for beer’s fruity aromas.

Alan Sprints, owner and brewmaster at Hair of the Dog in Portland, Oregon, has also been brewing in concrete for about four years, but his tank is different from the one at OEC. His is shaped like a giant egg. While practitioners of the biodynamic approach to agriculture believe there is mystical power in the egg’s shape, that’s not what attracted Sprints to the vessel. “Because it has no corners, it keeps the yeast in suspension longer and beer ferments faster,” he says.

He also plays around with concrete’s effect on different brews. “Education is a big part of what I’ve always tried to do with the brewery, resurrecting historic beer styles or creating new ones,” Sprints says. Visitors to Hair of the Dog’s taproom can sample different versions of the identical beer, categorized as “From the Wood” or “From the Stone,” depending on the vessels used to make them. Sprints has made every beer in his lineup in the concrete egg at some point. “Concrete really shines in making beer softer and rounder,” he says.

“I like the minerality, the softness, and the uniqueness that are made in that crazy-looking tank, but I’m not sure if it’s going to be the next great thing in beer,” Sprints says. “I’m looking forward to other brewers using these tanks, because I always learn things by seeing what other people do.”

He won’t have to wait long. Russian River Brewing Co. in Santa Rosa, California, recently received its own concrete egg. “To start, we will only age clean, non-funky beer in the egg, because once a porous surface like concrete is exposed to a wild yeast or bacteria, we never can be 100% sure we can remove it,” says owner and brewer Vinnie Cilurzo.

The first beer in Russian River’s concrete egg will be STS Pils. If all goes well, Cilurzo will try aging more adventurous brews in the egg. “I’m hoping the concrete will impart a nice minerality to the pils,” he says. “Long term, I’d like to get an egg for our funky brewery, where we make sour, barrel-aged beer. I know the concrete will meld well with some of the unique qualities we get from the Brettanomyces yeast and bacteria.”

ZX Ventures, a division within AB InBev, is an investor in October
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