By Bill Howell, for the Redoubt Reporter
If there’s one thing we Americans can’t abide, it’s a lack of change. We’re always chasing after the next new gadget, “new and improved” brands, the next big thing. Even in the world of craft brewing, certain styles rise and fall in popularity as brewers and drinkers continuously push the boundaries. These days, one of the hottest segments of the craft beer world is also one of the oldest and strangest — sour beers.
A couple of centuries ago, a sour beer would not have been uncommon, though it would hardly have been a desired outcome. Without an understanding of precisely how fermentation works or modern sanitization techniques, all beers would have had some degree of bacterial contamination, which would frequently have led to sour flavors as those bacteria multiplied and the beer became spoiled.
Certain bacteria can even produce copious amounts of extracellular polysaccharide, which form a viscous precipitate, or “rope,” in beers. Take my word for it, ropy beer is as disgusting as it sounds. Given this history, learning what caused beers to sour and how to prevent it was a real step forward in the evolution of brewing science.
However, in the ages before this knowledge was gained, brewers had to learn how to deal with the reality that beers were likely going to sour if kept long enough. They learned by trial and error not to brew in the warm days of summer, when such bacterial infections were most likely. They learned to blend overly sour batches with fresher beer to achieve a tolerable level of sourness before selling them to the customer. Eventually, regional styles developed for which a degree of sourness was considered a feature, not a defect. These classic sour beer styles include the German Berliner Weisse, and the Belgian Oud Brown, Flanders Red, and lambic beers.
Today, we know that the flavors in a beer that our palates perceive as “sour” are the result of acidity produced by bacteria known as Lactobacillus and Pediococcus. Such a sour beer is not to be confused with “wild” beers, which are characterized by the presence of Brettanomyces yeast strains. You can have beers that are wild, beers that are sour or beers that are wild and sour, as the two properties are independent of each other. When a brewer deliberately adds one or both of those bacteria strains to acidify a brew, it should properly be called a sour beer.
Let’s take a closer look at the players in this game:
First, there’s Lactobacillus. This bacterium (which is also what sours milk to create yogurt) is typically used to create sour German ales like Berliner Weisse, as well as the Oud Brown and Flanders Red ales from Belgium. Its fermentation produces lactic acid, which creates a dry, tangy profile in a brew.
Next, there’s Pediococcus. This anaerobic bacterium (which means it lives without oxygen) creates diacetyl, a chemical that produces flavors such as butterscotch and butter. It’s what’s in the stuff they put on “buttered” movie popcorn. Over time, diacetyl will be consumed by yeasts, resulting in a pleasant acidity, since Pediococcus also produces lots of lactic acid. An uncontrolled infection of this bacterium will produce the disgusting “ropy” beer I mentioned earlier. In a beer that is not designed to be sour, the buttery flavor of diacetyl indicates problems, like dirty tap lines or improper fermentation.
Finally, there’s Brettanomyces, which is a strain of yeast, not bacteria. Brettanomyces is slow-growing wild yeast that has an insatiable hunger, devouring complex sugars and carbohydrates that other yeast find indigestible, plus compounds like diacetyl. It typically produces a very dry beer with an earthy, horsey, leatherlike scent. It’s what makes a beer wild, but not sour.
So why would brewers even consider messing around with this witch’s brew of bacteria and wild yeast, risking contamination and infection of their “normal” beers? The reason is that, when deployed with skill, care and plenty of time, these scary little critters can produce some of the most interesting and exceptional beers in the world. These are beers whose complexity and tart, refreshing nature make them the match for any wine, and which pair exceptionally well with food.
If any of the above has piqued your interest in trying one of these sour brews, you are in luck. While none of our brewers here on the peninsula currently brew sour beers, the Anchorage Brewing Company has a reputation as one of the top brewers in the country for this sort of thing. It recently released an Anadromous Black Sour Ale, which was created utilizing all three of the above critters and then aged in more than 40 French pinot noir wine barrels before being blended and bottle-conditioned.
Sour beers are some of the most extreme beers out there, and are certainly not to everyone’s taste. But if you want to take a walk on the wild side, you should definitely give them a try.
Until next month, cheers!
Bill Howell is a home brewer, teaches a beer appreciation class at Kenai Peninsula College’s Kenai River Campus and was named the 2010 Beerdrinker of the Year by Wynkoop Brewing Company in Denver. He and his wife, Elaine, have released a book, “Beer on the Last Frontier: The Craft Breweries of Alaska — Volume I: Kenai Peninsula and Kodiak Island Breweries,” via Amazon.