“Sours” and “Funky” beers have really taken off in the Craft Beer culture over the past few years. You can go to your local store and buy styles like Gose and Berliner Weisse in cans with ease. We have seen the same trends in Home Brewing. More and more home brewers are brewing traditional lambics right in their garages. These beers take knowledge, dedication and and mostly time with some styles sitting for multiple years. For those home brewers who want to try their hands in making a “Sour” but are not ready to commit years and dedicate equipment and space to it, Sour Mashing is a technique worth exploring.
So what is Sour Mashing? Its a technique for adding acidity to a beer before boiling and fermentation begins by adding lactic acid to the mash once the mashing process is complete. There are a couple ways of introducing lactic acid; pitch a commercial vial of Lactobacillus that you can find at your local home brew store, or by pitching some unmilled grain which is the method we used in this article. If you want to read more about Sour Mashing check out this article on Milk The Funk. This is one of my favorite sources of information written by home brewers and commercial brewers.
Before we get into the Sour Mash brew day I wanted to answer some questions that I myself had before I started exploring brewing “Sours”. My first question was Do I need separate equipment? For Sour Mashing, no you do not need separate equipment. If you think about a “Clean” all grain brewing process you 1. Mash 2. Boil 3. Ferment with Sacc. In a Sour Mash process you 1. Mash 2. Sour 3. Boil 4. Ferment with Sacc. After the souring of the mash you are performing the same actions as a “clean” beer by boiling (sterilizing the wort) and fermenting with brewers yeast so technically speaking its a “clean” beer. Second, Do I need a separate mash tun for Sour Mashing since I am introducing Lactobacillus? No you do not. Lactobacillus is found on all grains. When you put grain into your mash tun, whether for a clean beer or a sour mash, you are introducing Lactobacillous and other wild yeasts/bacteria. Your mashtun is full of them anyway so you do not need a separate one. Remember the boil is was sanitizes the wort, so anything you introduce before the boil will be killed at the boil.
So what are the steps for Sour Mashing. Well its honestly really simple. First you Mash as you would any other beer (ex. 148F for 60Min). Once the mash is complete you chill the mash to 110-120F and hold it at that temp for 48-60hrs or until you get the sourness you are looking for. Once you have the sourness you want you begin your Vorlauf and Sparge as you would any other beer. From here on out the process is exactly the same. Boil for 60 minutes with your planned hop schedule, cooling to 70-75F for pitching temps. Sanitize your fermenter as normal and pitch your Sacc yeast. The process is exactly the same as a standard all grain brew day except for the 48-60hr Mash hold aka Sour Mash. So now its time to try it out and brew! Im going to walk through a Sour Mash brew day with my Gose recipe.
5.5 Gallon All Grain
5# White Wheat
2# Acidulated Malt (un-milled)
0.5# Rice Hulls
1# Vienna Malt (un-milled and separate)
1 oz. Tettnanger @ 60 min
1 oz. Coriander Seed @ 15 min
0.75 oz. Sea Salt @ 15 min
German Ale WLP029
OG: 1.053 FG: 1.013 ABV: 5.2% IBU: 14 SRM: 3
Mash: 147F for 60 min
Sour Mash: 117 for 48-60hrs
Boil: 60 min
Step 1: Mash
For the mash you want to combine the white wheat, pilsner, acidulated malt and rice hulls and dough in. Since we are going to sour mash we are going to run a thinner grist ratio so that a larger percentage of the wort is being soured. The goal is to have 5.5 gallons after boil so we want around 6.6 gallons of combined runnings before the boil. We also see a larger grain absorption factor since the grain has a longer contact period. So factoring that all in we want to strike grains with 5.5gal of water at 155F for a mash temp of 147F for 60min. That will give us around 3.75gal of first runnings (do not pull runnings yet)
Step 2: Cool Mash
After the 60min mash (or when sugar conversion is complete) we need to cool the mash down so we can pitch the Lacto. Optimal temperature for Lacto is between 110-120F so we need to cool the wort down into that range. I personally like to use a couple of 2L soda bottles that are filled with water and frozen. Ill take those and put them in the mash and stir until the temperature drops to 117F. Thats where I personally like to hold temperature.
Step 3: Pitch Lacto
As mentioned earlier there are a couple ways to pitch Lacto. Personally I like using unmilled grain. So thats the next step, pitching the lacto. Add the 1# of Vienna unmilled to the mash and stir it in. This acts as your lacto pitch and will start the souring process.
Step 4: Eliminate Oxygen
Oxygen is your worst enemy from this point on. The more oxygen present the more your beer will have this awful bile / vomit smell to it which likes to linger around into the finished product. To eliminate as much oxygen as possible you want to spray the bed with CO2. Get a nice blanket of CO2 on the grain bed and then cover it with saran wrap. If you do not have CO2 I would suggest putting the saran wrap directly on the top of the grain bed to eliminate as much head space as possible. In my case I had CO2 and wrapped the top of the vessel so that no oxygen would get in when the lid was put on.
Step 5: Hold Temperature for 48-60Hrs
Next is the fun part, holding 117F for 48-60hrs. As a home brewer this is actually the hardest part. If you are using a cooler mash tun it would be best to put it in the warmest part of your house and wrap it with a blanket. If you have heating pads or anything to help maintain the heat I suggest using it. You will usually see 10-15F drop within 24hrs and finishing around 90-95F after 48-60hrs. But you really want to try and keep the temperature as close to the 110-120F temp as thats the happy range for Lacto. In my case SsBrewTech’s InfuSsion MashTun is perfect for handling this. It comes with an optional MTSS (temperature controller and heating pad) that allows me to set a temperature and walk away. The controller will turn on the heating pad when the temperature drops below the set temperature and will maintain the mash temp within 1F. I was able to hold between 116-118F for 60hrs using this product and ive found it to be the ideal setup for Sour Mashing or Kettle Souring. If you are interested in the InfuSsion Mash Tun check out this blog post InfuSsion Mash Tun.
Step 6: Vorlauf, Lauter and Sparge
After the 48-60hrs and you got the sourness level you are looking for, the brew day goes back to normal. Begin your Vorlauf and lauter and collect your first runnings. We are aiming to get around 3.75 gal of first runnings. Begin your sparge with around 168F water to collect the remaining 2.85 gal of wort to total 6.6 gal in your boil kettle.
Step 7: Boil
Once you have gathered your 6.6 gal of wort you are ready for boil. This recipe calls for a 60 min boil with 1 addition of 1 oz. of Tettnanger hops at 60 min. During the boil you will also be adding the 1 oz. of coriander seed and 0.75 oz. of sea salt at the 15 min mark. Prepare your coriander seed while you are heating up the wort for the boil. You want to crack the coriander seed either using a spice cracker or putting the seed in a ziplock and cracking it with a rolling pin. By this time you should be about boiling. You really need to watch the boil for this beer. Since there is a lot of wheat in this beer you will get a lot of foam on the top of the beer while boiling which can cause boil over. Watch over the beer and adjust the heat source accordingly. When there is 15 minutes left add the sea salt and coriander seed.
Step 8: Chill and Transfer to Primary
Sour Mashing is a great way to start with producing “Sour” beers as its not that much different from a “clean” beer brew day. Once you get the hang of it you will get hooked and on your way to doing more traditional style “Sours”.
On a side note, I just want to comment on the piece of equipment I used to sour mash. Its the SsBrewTech InfuSsion MashTun, which I have brewed with before. But the newest addition to the Mash Tun was this MTSS. Its a temperature control unit with a heating pad that mounts to the bottom of the Mash Tun and is designed to hold temps to within 1 degree of the set point. I bought this accessory specifically for doing Sour Mash and Kettle Sour beers and this was my first time using it. Honestly it was the best investment I could have made. In the past ive wrapped my igloo cooler tun with blankets and tried to keep my temps up there but would loose 15-20F over the course of the sour mash which is not ideal. The souring process would slow down and off flavors and smells would start to develop the longer it sat at lower temperatures. Not with the MTSS, I was able to keep temps between 116F and 118F for 60hrs which yielded a more tart wort. I honestly was overly impressed with this option and if you are planning on doing some Sour Mash or Kettle Sour beers I would definitely suggest taking a look at this product. Here is the link MTSS Temp Controller.