Sour ales aging in barrels at The North Fork Brewery.

Many of our local breweries have even made – or are beginning to make – sour ales. Just to name a few: Aslan makes a delicious Berliner Weisse named Disco Lemonade, and I hear the brewery is currently working on a spontaneously fermented blackberry ale. The North Fork produces a slew of fantastic sour ales, and it recently released a spontaneously fermented beer – the first one of its kind from our area. At least a few breweries have made goses, including Kulshan, Boundary Bay and Menace. Atwood Ales just released its first Kettle Sour Blonde Ale. Wander offers a series of fruited sours under the Millie name, it just released a tasty dry-hopped kettle sour, and it will begin using its new coolship to make spontaneous beers this fall.

WHAT IS SOUR BEER?

Sour beer is a loose category of beer made with acid-producing bacteria, specifically various strains of Lactobacillus and/or Pediococcus, and it includes styles such as Berliner Weisse, Gose, some farmhouse ales (i.e., some acidic versions of Saison and Grisette), various wild ales, Flanders/Flemish Reds and Browns, Gueuze and Lambic, and other spontaneously fermented beers. These beers are almost always ales; sour lagers are rare. 

Many sour beers do not fit neatly into specific beer styles, and they can vary greatly when it comes to color, acidity, carbonation, residual sweetness, dryness and strength. Hop bitterness is usually kept to a minimum because bitterness clashes with sourness and it inhibits Lactobacillus. Dry hopping and late-addition hopping techniques are sometimes employed because they add additional aromas but very little or no bitterness. Some of the more heavily hopped sours are even being described as “sour IPAs,” which may make some people cringe. Epic’s Tart N Juicy Sour IPA is a great example, and if you can get past the label, it’s actually an insanely delicious and highly quaffable sour ale.

WHY HAVE SOURS BECOME SO POPULAR?

I believe there are two main factors responsible for this sour surge: 1. Increasingly, beer drinkers are discovering and falling in love with this genre of beers – both the old and traditional versions and the new and innovative interpretations, and 2. Lots of brewers have learned how to make them and, more importantly, make them affordably, efficiently and consistently.

Regarding No. 2, you can probably trace this sour surge back to some specific lectures at beer festivals and beer conventions not long ago. Before that time, there was little information online or in books on how to make sour ales. Thanks to those talks, the subsequent sharing of information between pro brewers (as well as experienced home brewers), collaborations with Belgian brewers, and some great sites on the internet (e.g., The Sour Beer Blog, The Mad Fermentationist, Milk the Funk, and The Sour Hour on the Brewing Network), we’re now brimming with sour-brewing beta. Plus, we now have some incredibly informative books, most notably “American Sour Beers” by Michael Tonsmeire, which came out a couple years ago, and “Wild Brews” by Jeff Sparrow.

It should be noted, however, that the vast majority of sour ales being produced by American brewers these days are kettle sours (or sour mashed beers, though this method has become less popular), which are quicker, cheaper and easier to produce than traditional aged sours, plus they can be made more consistently and they reduce the chance of cross contamination because the acidified wort is boiled (killing off the bacteria) before being transferred to other areas of the brewery. Kettle souring also allows the brewer to begin the boil precisely when the acidity (pH) reaches the desired level.

Some argue that kettle sours lack the depth and roundness of aged sours, but as long as they’re done well, I think they’re perfectly suitable for styles like Berliner Weisse and Gose, as well as some fruited or dry-hopped sours.

SOUR VS. FUNKY

“Sour” and “funky” are two different qualities. A beer can be clean and sour, it can be funky and sour, or it can be funky and not sour. Contrary to popular belief, Brettanomyces on its own does not produce sour beer. Brett can, however, add phenolics, esters, and even some vinegar-like acetic acid, all of which can leverage up that “sour” perception, but it doesn’t contribute any of that tart and twangy, mouth-puckering acidity that’s produced by Lactobacillus and/or Pediococcus.

Some kettle sours are inoculated with Brettanomyces yeast, which provides additional attenuation and sometimes added layers of funk, but Brett can take a long time to ferment and it’s unpredictable, so many brewers just stick to the Saccharomyces yeast and Lactobacillus bacteria combo.

HOW HIGH CAN THESE LOW-pH BEERS GO?

Regardless of how they’re made, sour ales across the board have become so popular that some people are calling them “the next IPA.” Bart Watson, chief economist for the Brewers Association, doubts the growth potential of the category as a whole:

“They can be difficult to make in large quantities, the startup costs are high for many breweries, their flavors are unfamiliar to many American beer drinkers, and they tend to have higher price points,” Watson says. “Certain brewers have clearly found success in wild/sour portfolios and I think will continue to do so, but in terms of the larger industry, the combination of challenges makes it unlikely we’re going to see sours go mainstream in the near future.”

I’m OK with that. As much as I like to see all these new sours on the market, more isn’t always better. No doubt, some brewers are jumping on the bandwagon for the wrong reasons and making sub-par, one-dimensional sours at best, or sours riddled with off-flavors at worst.

Just because a brewer can produce excellent “clean” beers does not necessarily mean he or she can immediately pick up sour beer brewing. It’s a complex realm of zymurgy that features a steep and agonizingly slow learning curve. There are many different ways to make sour ales, some of which are still theoretical, and there are few best practices in place to use for guidance. To add, blending, which is often necessary for optimal flavor and consistency, is a difficult-to-master art form on its own.

On the positive side of the growth, there are some amazingly delicious beers being made out there, including many fruited sours, dry-hopped sours, spiced sours and more.

Even though the first beers ever made were most likely sour, and some sour ales have been made in countries like Belgium for hundreds of years, it’s still a new frontier in brewing. And for creative and talented brewers, that frontier is limitless, as we have only scratched the surface of the flavor possibilities.