4 Ways to Sour a Berliner Weisse

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Berliner weisse is a low-strength German wheat beer that relies on a source of lactic acid to create a refreshing but intriguing sourness. As with many things in homebrewing, there is more than one way to achieve Berliner weisses’ signature tart character. Here we took a look at some of those options.

1. Add Food-Grade Lactic Acid

Arguably the simplest way to give your Berliner weisse a sour kick is by adding food-grade lactic acid to taste. An 88% lactic acid solution can be purchased from your local or online homebrew shop (find a homebrew shop near you). Lactic acid solution is often used to lower the pH or sparge water, but it can also be used to instill a sour tartness when added to the fermenter or just prior to packaging.

This method is convenient because you can precisely control the amount of sourness by taste-testing, and you are ensured that the sour profile will not change over time. The downside is many call the quality of the flavor, aroma and sensation of sourness from lactic acid solution into question.

Jamil Zainasheff and John Palmer liken the use of lactic acid solution to microwaving a steak in their book Brewing Classic Styles.”It is faster and easier, but the taste and texture is just not the same as with grilling [steak],” says Zainasheff and Palmer. It is said to sometimes cause harsh, medicinal flavors and can lack complexity.

Others report great experiences, particularly if trying to add a bit more sourness to a Berliner weisse that used more natural souring techniques.

2. Infect Wort with Grains

Most brewing grains tend to have a population of Lactobacillus, among other microorganisms, that can be used to naturally sour a Berliner weisse. Take a handful of milled base malt and add it to either the mash or wort. Allow the liquid to sit with the grains at 100°F (37.8°C) for 24-48 hours. This will allow the sour bugs to develop. On brew day, boiling the wort will stop the souring action at that point and leave a fixed amount of sourness.

This technique makes for a more complex sour profile compared to a Berliner weisse made purely with lactic acid solution. The downside is this method has a lot of variability in regard to the sour profile and other characterstics that are created. In some instances, you’ll turn out a great sour Berliner weisse, and in others you might be less pleased. A lot of this method relies on good old fashioned luck.

3. Pitch Lactobacillus delbrueckii Culture

Homebrew shops often carry cultures of Lactobacillus delbruecki, which can be pitched into wort as you would yeast. With this technique, you’d still ferment the beer with a neutral ale yeast, and include the Lacto culture to add sourness to your Berliner weisse. Some brewers will add the culture after a bulk of primary fermentation is complete with the ale yeast. The result is an intriguing sourness with depth from additional culture-derived flavor and aromas.

This method is said to be more reliable than using the grain technique discussed in #2, but with similar results if you happened to turn out a tasty Berliner weisse by souring wort with grains. However, when using a culture the profile of the beer will likely evolve over time, which can be good or bad. That being said, Berliner weisses were traditionally consumed shortly after they were brewed.

4. Blend with “Acid Beer”

The term “acid beer” is sometimes used to describe a very acidic beer with strong sour qualities. While on its own, the acidity of the beer might be too much for the beer drinker to handle, it makes for a great utility to blend with non-sour or under-soured Berliner weisse. This method, of course, will assume you have a highly acidic sour Berliner weisse available, which could be made with one of the techniques above depending on your preferences and goals.

After fermentation of your Berliner weisse, which could be a clean fermentation or using one of the techniques above, blend in the acid beer to taste until you reach your preferred flavor profile.

Sources: American Sour Beers: Innovative Techniques for Mixed Fermentations by Michael Tonsmeire; Brewing Classic Styles: 80 Winning Recipes Anyone Can Brew by Jamil Zainasheff and John J. Palmer; Brewing with Wheat: The ‘Wit’ and ‘Weizen’ of World Wheat Beer Styles by Stan Hieronymus; The Oxford Companion to Beer by Garrett Oliver et al; Wild Brews: Beer Beyond the Influence of Brewer’s Yeast by Jeff Sparrow.