For a good deal of human history, beers were sour just as a matter of course. Brewers work with sugar sources in warm, moist environments, which, although ideal for alcoholic fermentation, is also ideal for wild souring bacteria. Oak beer barrels were like hostels for this bacteria. It flourished in the nooks and crannies of the wood, and enjoyed a free meal of sweet unfermented beer while the brewer’s yeast wasn’t looking.
With the advent of stainless steel, these “spoiling” bacteria were able to be fully eradicated from the brewing world. Stainless steel couldn’t harbor stowaways as well, and was much more cleanable with caustic chemicals. Beer was forever changed, and sour beer was no longer the norm.
Some pockets of the brewing world have maintained the tradition of brewing sour beer, keeping traditional sour beer styles alive and preserving their legacy. As the craft beer movement has spread across the globe, maybe new brewers are embracing and recreating these styles in the modern era.
There are essentially two different camps of sour beers, what I’ll call “kettle-soured” and “live culture soured.” In this column I will explore the two main kettle-sour styles, Berliner Weisse and gose. And then in my next column, I’ll get into the wild world of lambics and Flemish sour ales.
Kettle-souring, also known as “sour mashing,” produces beers that range from tart to fully sour, but which are stable, meaning that they will not continue to become more sour over time. Barley and wheat are soaked in hot water, a process called “mashing,” during which sugars, enzymes and other compounds are extracted from the grain. Normally, once mashing is complete, the liquid, or “wort,” is drawn off the spent grain and boiled. For kettle-soured beers the grain is allowed to soak at warm temperatures, a scenario which encourages bacteria growth. Lactobacillus, a wild souring bacteria, grows naturally on barley, and once it is activated a lactic fermentation begins. Lactic acid is produced during this process, and once the desired level of tartness is achieve, the wort can be run off and boiled, killing the bacteria and locking in the acidity level in the beer.
This pale, low alcohol and tart wheat beer style originated in the eponymous city. The style name is now a protected term, much like Champagne and Gruyère, making Berlin the only authentic place where true Berliner Weisse may be brewed.
In 1806, Napoleon’s armies secured the city of Berlin, and the general paid a massive compliment to the wheat beers of the city. He is known to have been fond of Champagne and is said to have remarked that Berliner Weisse was like the Champagne of the north. It is tart and crisp, with tingly carbonation and exhibits a similar flavor palate as Champagne, with notes of lemon peel, quince, hay and lemon curd.
Historically, Berliner Weisse beers soured just as a matter of course. Today, they are intentionally soured in the brewing kettle. After the boil, Saccharomyces cerevisiae, also known as brewer’s yeast, is added to complete the alcoholic fermentation. The finished beer is typically at or under 4 percent alcohol by volume. Some modern brewers will include brettanomyces, a wild yeast, which adds to the level of dryness as well as a higher level of carbonation. Brettanomyces was likely present in historical examples for the same reason that the beer was originally sour.
In Germany, Berliner Weisse is often served with flavored syrups to offset the beer’s sourness and make it more approachable. Woodruff and raspberry syrups are common. Because of this tradition, some craft brewers will add fruit to the beer during conditioning.
For a traditional example of the style, look for Professor Fritz Briem (Germany) “1809 Berliner Weisse Style.” Smuttlabs (New Hampshire) makes some wonderful fruited versions under its “Short Weisse” series.
Gose, pronounced “goes-uh,” originated in the German town of Goslar, three hours west of Berlin by car. The town became known for a lightly sour, somewhat salty beer of modest alcohol content which was spiced with a touch of coriander. Similar to Berliner Weisse, goses were historically sour just by nature and now brewers will employ sour mashing (although they typically omit brettanomyces).
What makes gose unique from Berliner Weisse is its saltiness and the addition of a spice, which is normally verboten under the German beer purity law. (Historical styles are given a pass on this.) The saline quality was due to the town’s water supply, which was bordered by large salt deposits. To recreate this style, brewers operating outside of Goslar must add salt to the brew. The coriander adds a nice spiciness which helps to offset the salinity and acidity.
To check out traditional examples of gose, look for Leipziger Gose (brewed by Germany’s Bayerischer Bahnhof), Westbrook (South Carolina) Gose, Lost Nation (Morrisville) Gose or Simple Roots (Burlington) “Gose the Destructor.” For a less traditional, but equally delightful example, check out the brand new Long Trail (Bridgewater Corners) “Cranberry Gose.” The addition of New England cranberries plays nicely with the salt and coriander, but is restrained enough to let the “gose-ness” shine through.
In two weeks, I’ll be back with more about live culture sours. Stay tuned!
Jeff S. Baker II is the Curator of the Curriculum for Farrell Distributing. You can find him on Twitter and Instagram @aPhilosophyOf.