Beer 101: A Primer on Sour

18 March 2016
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Category: Beer 101
18 March 2016, Comments: 0

A Primer on Sour

Sour beer are big right now. I mean, not Star Wars reboot big, but they are definitely creating a buzz among the beer aficionado crowd. Sour beer used to be fairly simple. They were rare, old-style European beer that took months to create and were niche products.

But then the Americans got into the act. And like with most things American they want to do it big, fast and flashy. So in the last few years the world of sour beer has evolved surprisingly fast. So in this column I want to offer a bit of a primer on sour beer – the types it comes in and how they are made.

Let’s start at the beginning. Sour is

not normally an accepted flavour in beer, which should usually be sweet and bitter. Some styles can have a hint of tartness in the finish (such as Witbier), but generally sour is to be avoided. However, historically certain styles evolved to accent a noted tartness as a core characteristic of the beer. A sour beer should have a clean form of tartness; it should be fairly appealing on your palate. It can have a lemon/lime note or be a bit stronger, moving into an acetic puckering. Vinegar or pickling brine are big no-nos.

The Europeans have produced sour beer for centuries. They were never mass-market products, but there has always been a niche market for their particular qualities which allowed small, artisanal breweries to keep making them.

At the risk of over-simplifying I would classify the European sour beer into three families. In terms of perception the least sour of the families would be Flanders ales, in particular Flanders Red and Oud Bruin. These are Belgian-style beer that are fermented normally, the base beer being either an amber or brown ale. The beer are then aged for up to two or three years in oak barrels. The barrels have lactobacillus (the yogurt bacteria) and other bacteria living in the wood that slowly chew on the residual sugars in the beer. Over time the beer becomes drier and develops a noted sour tang.

In the Flanders tradition the aged beer is usually blended with younger versions to establish a balance between sweet and tart, creating beer that is not unlike a red wine or a lemonade. Good examples of Flanders ales include Rodenbach and Duchess du Bourgogne.

The second style is Berliner Weisse. Its very low alcohol levels, ranging from 2% to 4%, make it more of a refreshing thirst quencher than a beer. It is fermented with a combination of beer yeast and lactobacillus to create a very tart, puckering beer with a lemon-y, tart apple character. The beer is often served with syrup additions, including woodruff and raspberry to add both sweetness and other flavours to balance. Berliner Weisses are very rare in North America, so I don’t really have a good option to provide to you.

The third family may be the most revered. Lambics break all the rules of brewing. Spontaneously fermented, the brewer is actively looking for the beer to be inoculated by organisms other than beer yeast. They are then fermented slowly in wood barrels and aged for three years to allow the sourness to develop alongside other quirky flavours that impart an earthy, musty, tangy, rustic character. A 3-year old straight lambic is almost too puckering to be consumed. So the brewer either blends it with younger versions for balance (called Gueuze) or post-blending adds fruit for sweetness, colour and fruit flavours. Common fruits include cherry (Kriek) and raspberry (Framboise). Cantillon is the classic lambic brewery, but you can also find nice examples from Drie Fonteinen, Girardin and Mort Subite.

In North America it is much harder to identify specific families of sour beer as craft brewers here are much more

experimental. Many do Americanized versions of Flanders and Lambics (less so Berliner Weisse), using oak barrel aging and so forth. At the risk of over-generalizing

I find American versions to play up the sour angle more and often use unusual base styles to build the beer. Regardless, North American brewers have fully embraced the sour thing and are producing many new versions.

The latest thing in sour beer is something called Kettle Sour. Kettle sours reverse the process. Before boiling the wort is inoculated with lactobacillus (often an actual addition of yogurt) left to sit in the boil kettle for 24-36 hours, dropping the pH. The wort is then boiled and fermented as normal. Instead of waiting three years to get the right level of puckering, it is a matter of a day or so. Kettle soured beer lack the complexity of traditionally soured beer and are a bit cleaner and lack earthiness, but they can be quite refreshing, all without the risk and time delays of regular souring. Alberta breweries who have tried their hand include Wild Rose and Blindman Brewing.

Sour beer is not for everyone. It is definitely an acquired taste. However, tartness is a common flavour in the world of food and beverage and if one appreciates a fresh lemonade or a sweet-puckering whiskey sour then the prospect of a Lambic or a Kettle Sour isn’t such a stretch.


Jason Foster is an Alberta-based beer writer, educator and certified beer judge. He is the beer columnist for CBC Radio’s Radioactive, Edmonton’s Vue Weekly, Saskatoon’s Planet S Magazine and writes regularly for a variety of magazines. He is also the creator of onbeer.org, a website devoted to craft beer on the prairies and beyond.

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