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What is a sour beer anyway?
Well actually normal beer is already sour in respect to water. Typically “normal” beer is in the pH 4-4.5 range. A sour beer is usually in the pH 3-3.5 range. While this doesn’t look to far off each other a pH of 3 is 10 times more acidic than a pH of 4 🙂
Kettle souring
There are many ways of souring beer but the easiest to accomplish in a relatively short timespan is kettle souring. Kettle souring is done in the boil kettle – hence the name – and is usually a result of acid additions and lactic acid bacteria (lactobacillus) to produce sour wort. After reaching the desired pH level you lock it down by boiling the wort killing off the lactic acid bacteria and you pitch yeast as normal. Or – if you’re into it: No boil at all!
Ingredients
Sour beers are typically light, have low bitterness and adjuncts like fruit are common.
Grist
Go light, sour beers doesn’t play very well with caramalt. A Berliner Weisse are 60-50% wheat and the rest pilsner. Wheat complements the sour taste so does rye. All pale or a very small colour addition works as well. Berliner Weisse is a low ABV, dry beer with an OG of about 1.030 and FG of about 1.005. The style plays well with IPAs at OG up to 1.060 or so.
I do recommend a 1.2mm crush for the Brewie though.
Hops
Sour beers usually have low bitterness. The Berliner Weisse stands out at seriously low IBU of about 5! That’s just a few grams of low alpha acid hops added at the start of boil to help sanitize the wort. Sour IPAs typically have a few grams of hops added for bitterness and the rest at whirlpool and/or dry.
Adjuncts
Classic german Berliner Weisse is served with syrup in the glass but most modern sour beers have adjuncts added during fermentation. Fruit that plays well with the tartness of a sour beer are your most typical adjunct.
Choice of lactic acid bacteria
The lactobacillus are a huge family of bacteria found in everything from body cavities to yoghurt. Most of them require a stable temperature in the 30-40C range. Since (the time of writing this) Brewie doesn’t have support for a kettle souring process keeping the temp in this range is difficult. The easiest way out is choosing a family member that isn’t so picky about temperature: Lactobacillus plantarum. The L. plantarum is a well known probiotic and good for your tummy. This means it’s available in various capsules at drugstores as well as assorted homebrew shops. The easiest would be to grab a pack of Lallemand’s WildBrew Sourpitch as it’s already dosed for brewing purposes – check your LHBS.
Anyway – the L. plantarum prefers to be pitched in the 30-40C range but doesn’t care if the temp drops to room temp (20C) afterwards.
Extra equipment needed
In addition to the ingredients and lactobacillus you may need some extra equipment. These aren’t mandatory but they make it easier to make a clean sour.
- A big syringe (50-150ml) and a small piece (5-10cm) of food grade tubing that fits the tip of the syringe
- Preferably a pH meter – or blindly trust my recipe
- Lactic acid 80%
- Plastic wrap/cling film
We’ll get back to how they are used during the process.
Thomas Valsø Solberg
Want to know more? See how Chris makes his beer and educate his children at the same time!
