keg of beer
Photographs: Tyler Graham



cience has always fascinated me. Thinking back to that first vinegar and baking soda volcano I made in Ms. Summers’ class, it’s safe to say that my obsession with learning the “hows” and “whys” behind everything began erupting early in life. And through this incurable fascination, I’ve come to garner an even greater appreciation for natural processes that don’t have a complete explanation. They force us to tip our hats in deference to Mother Nature, who, despite innumerable scientific breakthroughs over the millennia, still has plenty of little tricks up her sleeve that we may never fully comprehend. And I, for one, dig that.

In the case of beer—certainly one of my favorite subjects to study—there’s still a wondrous amount of academia that can be carried out on the metamorphoses that take place during and after fermentation. The very idea of the process itself is a bit taken for granted: you add the yeast, it eats the sugar, makes alcohol and carbon dioxide, et voilà, right? But before the 1880s, there was no “yeast” as we know it. Sure, it existed, but it hadn’t yet been discovered as the little soldier responsible for making booze and the beloved buzz associated with it. Fermentation was considered a divine process, with the credit given to an invisible ingredient named “Godisgood” which miraculously made its way into the mix and turned barley water into beer. This transformation often relied on yeast and bacteria that were naturally present in the air, which would inoculate the beer-to-be, sparking what we now refer to as spontaneous fermentation.

Yet, there are still a few small brewers making beers the old school way, leaving it up to airborne microorganisms and chance to dictate what the final beer will taste like. The most notable and celebrated of these brewers is Jean Van Roy of the 112-yearold Brouwerij Cantillon, located in Brussels. He’s devoted his life’s work to crafting different kinds of Lambics: traditional, tart Belgian beers that are spontaneously fermented and aged in wooden barrels, a process which allows their character to develop… ever so slowly, but surely.

Lambics, like all sour beers, take months or sometimes years to mature fully. They are the by-products of a variety of different yeast and bacterial cultures that produce one heck of a flavor spectrum. “A Lambic brewer has no possibility of control or domination over his beers,” explains Van Roy. “So for me, the best way to produce this style is to work with it… together. They’re wild beers, and I don’t try to domesticate them. They will tell you when they are ready.”

Several US brewers have taken inspiration from the sour beers of Belgium and beyond, developing their own interpretations here, though they admittedly tend to shy away from the idea of spontaneous fermentation. Instead, they opt to have some of the yeast and bacteria typically at play in sour beers cultured for them by special labs. This does provide a small bit of insurance to the brewer, as it allows them to guide the early fermentation, sending the beer down a clearer path rather than leaving it entirely to Mother Nature’s whim.

“They’re wild beers, and I don’t try to domesticate them.
They will tell you when
they are ready.”


But as soon as one of these beers—spontaneously fermented or not—hits a barrel, it’s a whole new ballgame. Chris White, eponymous president of San Diego’s White Labs and co-author of Yeast: The Practical Guide to Beer Fermentation, explains, “If the barrels were used to hold wine or beer previously, not only is some of that flavor going to carry over, some of the cultures will too. It’s like a giant Petri dish in there!” White continues, “And each barrel really does take on a life of its own. If you filled 20 different barrels with the exact same beer, in the end, you’re going to get 20 vastly different variations of that beer.”

So how on earth do these brewers manage to produce anything even remotely consistent? Enter the art of blending. “One batch might have a bit more body than another,” begins Patrick Rue, CEO & Founder of The Bruery in Orange County. “Or one could have an amazing aroma of leather, while another is strictly sour and fruit without any of the rustic aromas or flavors. By blending these largely inconsistent beers, we’re able to achieve something that is pretty close to previous batches by combining the different elements of each.” “Blending is probably the most important part of my work,” adds Van Roy. “The beers can come out of the barrels tasting sour, sweet, bitter, insipid, woody, salty, fruity, and so on. That’s what makes the blending so important; it offers a balanced representation of all the flavors present in our brewery.” One of the many risks inherent with barrel aging beer is that it can—and sometimes does—go downhill during the long maturation. “If it gets overly acetic, tasting too much like vinegar, we’ll dump it. If it gets a solventy acetone character, we’ll dump it,” explains Rue. “The flavors can peak and turn pretty quickly, but making these styles is part of who we are, so the risk is calculated and necessary to be who we want to be.”

Other times, it just might not meet standards. “If we taste a beer after one year in the barrel and we’re not thrilled with it, but we think there’s still an opportunity for it to mature, then we’ll hold it,” says Tomme Arthur, Director of Brewing Operations at The Lost Abbey in North County San Diego. “We’ll give it another 18 months, and if nothing has evolved by that point, we move to dump it.” “If a barrel beer doesn’t taste right, we’ll just dump it,” agrees Vinnie Cilurzo, Brewer/ Owner at Russian River Brewing Co. in Sonoma County. “It’s a really easy decision for me to make.” Sad as it may be to think about beers being poured out after such a long and delicate process, it speaks volumes about the strict standards that these brewers hold themselves to. Cilurzo adds, “It’s very important that every brewer in the U.S. sets the bar very high, and then meets or exceeds it.” Cilurzo is one of the few American brewers who, besides making stellar sour beers with pitched cultures, also braves the wild.

He produces a 100% spontaneously fermented beer he calls Sonambic (a Sonoma/Lambic portmanteau), and while a majority of it is mixed into other beers to add complexity and acidity, some Sonambic barrels are held back and blended with each other to create a wonderfully transcendent—albeit rarely released— beer called Beatification. Arthur has also dabbled in spontaneous fermentation, creating a beer known as Project X. Though it hasn’t been made available on its own, it has found its way into blends for several recent and forthcoming releases.

As to why these brewers don’t leave more beers to chance with airborne yeasts, Cilurzo cites space constraints. Arthur rightly boasts, “I think we’re making some fantastic beers as is, so why mess with less predictable?” Rue, who hasn’t made any beers with spontaneous fermentation, offers a different take: “If we were next to orchards, I’m sure we’d give it a try. But the fact is, we’re adjacent to a freeway, and I don’t think we’d get great flavors from brake dust and roadkill.”

Regardless of how much or how little they employ spontaneous fermentation, van Roy—our traditional Lambic producer from Brussels—approves. “I like all these brewers; they’ve found new channels that allow for sour beers to flourish. As these older styles continue to see more and more success, I know it’s thanks to people like them. Indeed, our production methods may differ, but they’re making very good stuff.”

In Illa Brettanomyces, Nos Fides


Patrick Rue and Chris White break down the most common types of yeast and bacteria found in sour & wild ales.


Produces an interesting funk, often described as musty or “barnyard.” Can contribute tropical fruit flavors and earthy qualities. Also produces acetic acid, which adds a vinegary tartness. Interesting to note that Brettanomyces can digest many sugars other strains can’t, including wood sugars within the barrels!


Responsible for lactic acid production, as the name implies. Can contribute some of the “barnyard” or “horsey” character often attributed to Brettanomyces.


Also creates lactic acid, but unlike Lactobacillus, does not produce carbon dioxide. A littleheartier than Lactobacillus.


Traditional brewers yeast that metabolizes most of the sugars, producing a majority of the alcohol.


Various styles of sour & wild ales that you may encounter.


Very fruit forward, with a noticeable acetic acid backbone. Known as “the Burgundy of Belgium” because of its deep red color and vinous character. Often a blend of young and old beer for added complexity.


Also known as “Oud Bruin,” Flanders Brown ales have some tartness derived from long aging with Lactobacillus cultures, though the flavor of this style is fairly fruit- and malt-centric, and can come off as slightly sweet. Fermentation takes place in stainless steel tanks, not wooden barrels.


Traditional spontaneously fermented sour beer from the Senne valley of Belgium. A tart but balanced acidity melds with “barnyard” flavors and aromas redolent of earth, hay, and leather. No carbonation.


A blend of one-, two-, and three-year-old Lambics. Incredibly complex, as it mixes the fresh zip of younger beer with the refined, developed maturity of the aged beer.


A beer aged with raspberries.


A beer aged with cherries.


725 4th St., Santa Rosa |


A sour blonde ale aged in Chardonnay barrels for 9 to 15 months.


A sour brown ale aged with sour cherries in Pinot Noir barrels for around 12 months.


A sour dark ale aged with currants in Cabernet Sauvignon barrels for 4 to 8 months.


Spontaneously fermented “Sonambic” (Sonoma Lambic). Very limited quantity, typically a brewery-only release.

155 Mata Way, San Marcos | @lostabbey


“Judgement Day,” a Belgian-style Quadrupel ale, aged with sour cherries in a mixture of French oak, brandy, and bourbon barrels.


“Lost and Found Abbey Ale” aged for 9 to 12 months with raspberries in red wine barrels made from French oak.


“Dawn Patrol Dark,” a mild brown ale, aged with sour cherries in red wine barrels made from French oak. Beers aging for between 9 to 18+ months are blended.


A year-long series of new beers being released each month. These music-inspired brews are blends of The Lost Abbey’s barrel aged beers. Due their very limited quantity, they’re only available for on-site consumption at the brewery.

915 Dunn Way, Placentia | | @thebruery


A German-style sour beer, low in alcohol, with a crisp acidity from Lactobacillus.


As the name implies, this is an ale brewed with the addition of rye, and aged in oak barrels for 12+ months.


Flemish Red Ale aged in red wine barrels for 18 months. Vitis Series Two releases have come from this program: Pinotlambicus, a sour blonde ale aged with Pinot Noir grapes, and Oui Oui, a sour blonde ale aged with Chardonnay grapes.


A selection of small-batch beers that are sold only through The Bruery Provisions retail store in Old Town Orange. Some sour selections, like Tart of Darkness and Mother Funker, have come through this program.

stack of beer kegs

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