Kettle Sour: or How I Learned to Stop Worrying and Love Sour Beer

This blog was written by our member and frequent sour brewer, Ben Martin. Enjoy!

Are you a fan of sours, but don’t have the time and space to commit to 3 years? Afraid of infecting your clean brew house? Want to get out of the pale lager rut? Are you looking for a way to appease the hipster cult that lives next door? Well then this guide is for you! If not, keep reading you might learn something, maybe.

Disclaimer

This guide is simply a breakdown of the process I use to brew kettle sours on my system. I am by no means an expert. Your experiences may vary from mine. Words of warning, if you plan on attempting this, then you are making sour beer. This process limits your risk of infecting your brew house, but only if you practice good sanitation. Second, sour beer is more of an art than a science. Don’t be afraid to dump bad batches.

The Process

Goodbelly Probiotic Shot

Kettle souring is much like performing a normal brew day with a few added steps in the process. Equipment-wise, if you can brew a clean beer, you most likely have everything you need to brew a kettle sour. The one piece of equipment that is required/highly recommended is a pH meter. You will want to measure the drops in pH during the kettlesouring process.

Kettle souring begins like a normal brew day. Perform your mash as you normally would. Personally I brew BIAB (Brew In A Bag). I perform a 70 minute mash on an induction burner keeping my mash around 150°F. After the mash I squeeze my grain bag to free up as much wort as possible.

Pitching Goodbelly into wort.

The next step is the kettle souring step. During this step is the only chance to contaminate your brew house. Bring your wort to a brief boil to sanitize the wort and kill off any unwanted yeast or bacteria naturally present in the wort. After a brief boil chill the wort down to 100°F. Pre-acidify the wort to a pH between 4.2 -4.5. This will help prevent unwanted bacteria from growing in your wort and creating off-flavors. Pitch a pure lactobacillus culture and seal the kettle. Wait for the terminal or desired pH to be reached.

 

Anvil Brew Kettle with Ferment in a kettle gasket.

My kettle souring step looks like this; after the mash I bring my wort to a boil for 15 minutes. I then chill the wort to 110°F. I measure the pH and pre-acidify the wort to pH 4.2. During this step my temperature naturally falls to my target pitch temp of 100°F. Then I spray StarSan around the inside of the kettle and on the lid. I pitch a Goodbelly Probiotic Shot.

This contains a pure culture of lactobacillus planetarum. Then I seal up my Anvil kettle using the fermenter conversion kit. I let my kettle temperature free fall to room temperature over 3 days. By then my terminal pH, normally 3.6, has been reached.

Anvil Brew Kettle sealed for souring.

After you reach your terminal pH, it is time to resume your normal brew day. Bring the soured wort up to a boil, add hops according to your recipe, chill and pitch your yeast. This boil sterilizes the batch and kills the lactobacillus. This allows you to use your clean cold side equipment for the batch. Due to the low pH of the wort, yeast will experience acid shock. It is important to note that you need a large and healthy yeast starter to pitch.

Gose with blackberries and raspberries.

The rest of my process works as such; I bring my soured wort to a boil for 15 minutes. Add a small dose of hops to reach around 8 IBUs. Chill the wort to 72°F and pitch yeast. I normally chose Imperial A20 Citrus for all my kettle sours. I then let the fermentation ride. I do not have temperature controlled fermentation. If I plan to add fruits, I will typically add them towards the end of active formation on the 5th day from pitching yeast. The fruit will sit for a week before kegging. I normally target 1-2lb of fruit per gallon.

Dry hopped kettle sour with hop garnish.

 

As I stated, I am not an expert. There are plenty of people who know more about this than I do. Here are a few of the best sources for more information on kettle sours and sour beer in general.
Milk the Funk Wiki (This group also has a Facebook group, but if you ask a question the first thing they are going to say is read the wiki.)
The Sour Hour Podcast
The Mad Fermentationist Blog
Dr. Lambic Blog

How I Got Started: Erik Howell

Let me start by introducing myself. My name is Erik Howell. I’m an Indianapolis native that recently moved to Portland, OR and have been brewing for just over 10 years. I love all forms of fermentation, and would consider myself a “maker/survivalist”. Haha. Sounds better than “doomsday prepper” doesn’t it? I first got introduced into craft beer in the early 2000’s when I was in college. There was a craft beer bar just down the street from my house called The Heorot Pub and Draught House that had an excellent selection of great beer from all over the country/world. They had a mug club that allowed you to get a special mug if you bought one of each beer they offered in the bar. I tried as many different beers as I could afford, however there was no touching that achievement 🙂

I remember a friend’s misfortune with his Mr. Beer kit in college, and I was absolutely certain I could do better. I ended up with the same Mr. Beer kit as a Christmas gift in ‘06 and went absolutely nuts. I did a bunch of reading (The Complete Joy of Homebrewing, How to Brew, Radical Brewing, etc) and went a little overboard on sanitizing. In the very beginning I was literally wearing a facemask and covering my countertops with Saran Wrap sprayed down with StarSan solution. It was like a scene out of Breaking Bad. My roommate at the time was super inspired, and footed the bill for a 5 gallon kit from Great Fermentations that I started using pretty regularly. I was an extract brewer for a long time (admittedly the first 5 years). The beer I was making was OK. I continued to acquire equipment and fine tune my brewing practices and things got much better over time.

I started a small beer tasting group/blog in 2012 called Beer is My Passion or B.I.M.P. We organized blind tastings in an effort to educate ourselves about what we liked and disliked about different styles of beer. Later I formed a homebrew club out of the group, and started pouring homebrew at beer festivals. It was so much fun! Right about this time I met my soon to be wife Jenn, and we started brewing together. We got involved in competitions, more beer festivals, and networking in the Indy beer community. We were officially out of control. Soon we were branching out into cider, wine, pickles, etc. Beer turned into a gateway for all things fermented.

After a few years running BIMP, I found that many of my friends were more interested in the blind tastings than they were in brewing competitions. I was now working part time at my local homebrew shop, and was meeting other like-minded homebrewers that were also entering competitions. We were all competing independently even though we supported each others successes and failures. Ultimately this new group of brewers grew into Circle City Zymurgy. Now that I’m in Portland, I certainly miss my friends, the meetings, and social events that CCZ hosts. I still have a small hand in maintaining CCZ’s website, and still enter beers via our club. Recently I’ve been making various meads, wines, and beer in my new home. I’m hoping to build steam for the coming year’s competitions, and who knows maybe I’ll see some of you at NHC in Portland next year!