Sours Galore

July 25, 2014

American Sour BeersIn recognition of Wyeast’s new private collection sour blends and the release of Michael Tonsmeire’s (aka The Mad Fermentationist) new book, American Sour Beers, I thought I would talk a little bit about sour beers.

Sour beers can be intense for the uninitiated but once you start acquiring the taste you will notice a great complexity and refreshment. The traditional European sours are Berliner Weisse, Flanders Red, Oud Bruin, Lambics and Geuze. And now the Americans are taking off with sour and barrel aged beers. Just about any beer style can be soured, but it is best to use styles that won’t clash with the sourness and funk flavors. Saisons, pale ales, even porters and stouts can work with some sourness to them, big hoppy beers not so much.

The sourness in these beers come from the blends of yeast and bacteria used to ferment them (often referred to as “bugs”). The main souring bugs are Lactobacillus, Pediococcus, and Brettanomyces. Lactobacillus is the bacteria that turns milk bad. Its by product is lactic acid which is a smooth, pleasing sort of sour. Pediococcus also create lactic acid but more aggressively and can create a lot of diacetyl (buttery flavor) and a snotty like mouthfeel. It is almost always pitched alongside with Brettanomyces which will clean those flavors up.

Brettanomyces (or Brett) is a non-spore forming genus of yeast in the family Saccharomycetaceae. The word Brettanomyces is Latin for British fungus. It is a bit of a misnomer to say that brett sours beer as it adds more funkiness, flavor and tartness than sourness. It’s the lacto bacterias that really do the souring. There are three main types of Brettanomyces:

  • Brettanomyces bruxellensis is known for giving sweaty “horse blanket” flavors and aromas
  • Brettanomyces lambicus is known for giving cherry pie like flavor to beer
  • Brettanomyces claussenii is known for having fruity pineapple like qualities in beer. It was originally isolated from strong British ale

Many yeast labs also sell blends of some or all of these for different flavor profiles. The quickest way to sour a beer is to kettle sour. This involves creating your wort, cooling it down to around 120F and either pitching in some Lactobacillus or a handful of crushed malted barley (which contains lactic acid bacteria) and letting it sit at that temp for a day or two until your wort is the sourness you would like. Once it is there you bring you wort to a boil as usual, add your hops and ferment with an ale yeast of your choice. This is a good way to make Berliner Weisse which is basically 50% wheat malt and 50% pilsner malt. It helps to have a heating blanket to wrap around the wort to maintain the temperature while the souring is taking place. It is also a good idea to purge your wort of oxygen with some co2 and cover it with plastic wrap to keep it from oxidizing. If it oxidizes you can get a cheesy flavor that will not boil or ferment out.

You can also pitch Lactobacillus to boiled and cooled wort to sour it, you will still have to pitch yeast for fermentation. Keep in mind your IBUs have to be low. Hop alpha acids keep gram positive bacteria (like lactobacillus) from reproducing. This is how they keep beer from spoiling. Luckily yeast is gram negative. On a side note, acetobacter (which creates vinegar) is also gram negative so hops have no affect on them. Keep your equipment clean!

Other styles like Flanders Red Lambics and Geuze (which is a blend of young and old lambics) are traditional worts that are then inoculated. Worts that are going to be soured do well with warmer mash temps to create more dextrins, which are long chain sugars that common yeasts cannot ferment. Brettanomyces can ferment dextrins, so a more dextrinous wort will create more interesting flavors when using brett. You can pitch all brett into your wort or a blend of brett, saccharomyces and bacteria. Either way it will take months before you get the brett character you are looking for.

One of the new Wyeast sour blends, De Bom Sour Blend, is said to be able to finish up a Lambic in one to two months. The trick is no O2/aeration at beginning of fermentation, periodic dosing with O2 during fermentation (shaking the fermenter is sufficient), and sample periodically for taste and final gravity. Since brett can eat sugars that other yeasts cannot, you want to make sure you are done fermenting before bottling to avoid bottle bombs. It is also a good idea to repitch about a gram of fresh dry ale yeast for five gallons at bottling time to insure carbonation.

It is good practice to reserve the fermenters and tubing and such on the cold side of making a sour beer for sour beers. Many of these bugs have a biofilm that makes them hard to clean and sanitize. Using them for non sour beers just might sour them anyway!

If you are new to sour beers, go to your local bottle shop and try a Berliner Weisse or a Flanders Red (Rodenbach Grand Cru is my favorite) or one of the many new American sours out there (Peekskill Simple Sour comes to mind). You will be pleasantly surprised.

Sour but happy.



  1. Patrick McHale, July 28, 2014
    Nice write-up! We just did a sour brewing lecture/tasting at our shop, really interesting topic for brewing, I don't know if I have the patience to make one myself! For anyone looking to get into the style, I definitely recommend starting with a good Berliner Weisse, Evil Twin has a nice one out now called Nomad. Cheers!
    • brewer, August 2, 2014
      Hey Patrick. Thanks for the kind words and advice. I am looking forward to coming out one day and visiting your shop. Lots of luck to you!