Petaluma brewers find sweet success in sour beer

When beer lovers come to Sonoma County searching for sour beer, they typically think of the full-flavored, provocative sours of Russian River Brewing. Aged in repurposed wine barrels, these rich ales can be stored for years, with or without fruit additions, and showcase a brewers ability not only in the brewhouse, but also in the cellar. This process takes time, and that time makes its way back to the consumer in the way of a higher price point.

Despite the high price and limited availability of sours, especially those from the most highly regarded breweries, these mouth-watering beers have become one of the most popular niches of the beer industry. But sour beer is a tough concept. Techniques involving barrel-aging take time and therefore have a slower learning curve. Even the term “sours” is misleading, as there isn’t a unified style.

Souring of beer can be done in many ways, but there are three primary culprits when it comes to the acidic world of beer: brettanomyces, or “Brett,” pediococcus, or “pedio,” and lactobacillus, or “lacto.”

Brettanomyces is a yeast, and a slow-acting one at that. Voracious, Brett will, over time, completely ferment any sugar out of your liquid. The results can vary wildly, but Brett is prized for the tropical notes and earthy funk it can impart upon a beer.

Pediococcus is not a yeast but a bacteria. This infectious addition takes the tart, bright flavors imparted by Brett and adds a darker, deeply-seated sourness to the beer. Wild and aggressive, pedio beers are typically long-aged barrel beers and have a long history in Belgium.

Lastly, we get to lacto. Lactobaccilus is the same bacteria that makes your yogurt tart. The result is a clean acidity, one with few rough edges distinct from pedio.

It’s lactobacillus that’s making big changes to the beer scene these days. With demand surging but time and costs being deterrents, brewers began looking for new ways to make sour beer without the barrel. “Kettle souring” became the new buzzword.

Grains and water are allowed to sour for 24 to 48 hours before brewing, imparting a strongly acidic flavor to the beer before the brew day has even begun. Once started, the brewing process halts the lactic fermentation that had soured the mash, resulting in a controllable, shelf-stable sour beer that can be ready for consumers just as quickly as an IPA or any other type of ale.

While the industry has taken a shine to kettle-souring recently, the technique dates back centuries to Berlinner Weisse and Gose (GO-zuh) brewers of Germany. These two styles are the most popular of the kettle-soured genre and are appearing on store shelves in droves.

Locally, Lagunitas recently released Aunt Sally, “A unique, dry-hopped, sweet, tart, sour mash ale.” Aunt Sally ignores traditional style boundaries, being neither a Berlinner Weisse nor a Gose, and applies a typical Lagunitas-style hopping as well as an uncharacteristically-potent 5.7 percent strength.

With demand high, we will continue to see more and more kettle-soured ales, and experiments with these styles, making their way to our taps and shelves. For some, the biting lactic sourness is refreshing in a world of IPAs. To others, sour beers are simply just that, beers that have turned. Only time will tell if these style are here to stay or drift back into obscurity.

(Mario Rubio lives in Petaluma and writes the beer blog, BrewedForThought.com. He can be reached at mario@brewedforthought.com.)