How To Make Kettle Sour Beer (Ultimate Guide)

Sour beer is increasing in popularity and sales, so if you’re a homebrewer, you might be tempted to hop on the sour train. However, brewing your own sour beer can be daunting if you’ve never done it before. 

To make kettle sour beer, you must first decide what type you want to make and gather the necessary equipment and ingredients. Then, prepare a wort and add lactobacillus to the kettle, which will give the beer its sour taste. 

In the rest of this article, I’ll explain in detail what kettle sour beer is and how to make it yourself. Keep reading if you’re ready to get creative and make a tart and delicious brew. 

Making Kettle Sour Beer

1. Decide on the Type of Beer You Want To Make

You’ve already decided you want to make a kettle beer, but there are various styles you can choose from. Here’s a table with a brief overview: 

Type Description Flavor 
GoseWheat ale native to Goslar, Germany Salty, lemony 
Berliner Weisse Wheat ale native to Berlin, GermanyTart, hazy 
Sour IPA Blend of hops and sourness Fruity, tropical 
Milkshake Sour Sour beer brewed with lactose Fruity, creamy 
Fruited Sour Beer with fruits added, such as blueberries, cherries, or mangoes Fruity, juicy, complex
Coffee Sour Sour beer aged with coffee Creamy, tart, nutty 

Once you’ve determined what style you want to go for, you can begin the brewing process. 

2. Gather the Necessary Equipment and Ingredients

Brewing a sour falls into intermediate to expert-level homebrewing, so I assume you already have a homebrewing kit. 

If you don’t, you can check out my article on the best home brewing kits for beginners for recommendations.

Most home brewing kits have everything you need, but I want to highlight a few pieces of equipment that are especially important for kettle souring: 

  • A stainless steel mash tun, otherwise known as a kettle. The kettle is where the magic of the souring happens, so ensure that you have a kettle that’s up for the task. 
  • A pH meter. You’ll know when your beer is done souring and fermenting by checking the pH level, so you’ll need a reliable pH meter. I recommend this PmoYoKo Store Digital pH Meter from Amazon. It measures pH, temperature, and total dissolved solids, so you can use it for more than one purpose. Additionally, the algorithm chip and the electrode of the digital pH tester are accurate and quick. 
  • An electric blanket. A blanket is something your homebrewing kit probably didn’t come with! You may want to use an electric blanket to maintain the temperature of the beer as it sours. 

If you’re feeling overwhelmed by all the equipment included in the homebrewing process, don’t worry! I have an article that breaks down all the equipment needed for brewing beer.  

Not only do you need equipment, but you also need the ingredients as well. Here’s what you should gather: 

  • Lactobacillus, preferably a pure culture  
  • Lactic acid 
  • Malt
  • Wheat
  • Yeast, preferably a pure and strong strain  
  • Hops 

Once you have everything you need, clean and sanitize everything so you’re ready to start the kettle souring process. If you’re not sure about the best way to clean your equipment, I have a guide that gives you all the tips and tricks you’ll need. 

3. Make Your Mash and Collect the Wort

This initial step is no different from other kinds of beer, so prepare your mash however you’d like to. You can use an all-grain system, brew in a bag, or some other method. Allow your mash to rest for an hour.

If you’re unsure if your mash is ready to be sparged, you can use iodine to test its readiness. Take a mash sample and add some iodine. If the color doesn’t change, you’re ready to collect your wort.  

Don’t feel bad if you’re still confused about the difference between mash and wort! It is a bit confusing and stumps a lot of beginner homebrewers. Check out my article explaining the differences between mash and wort for further explanation.  

4. Heat the Wort

Next, heat the wort for at least ten minutes to kill any bacteria lingering in the kettle. Lactobacillus is a sensitive probiotic, so it is essential that everything is completely sterile and prepared before you add it. If other bacteria get in, they could end up ruining the taste of your beer.

5. Cool the Wort

After you’ve heated the wort and eliminated any bacteria, you need to get it back to the proper temperature needed for a successful brew, depending on the strain of lactobacillus you’re using. Usually, this temperature is around 100 degrees Fahrenheit (38 degrees Celsius). 

The vendor that you bought the lactobacillus from should provide this information. You can either wait for the wort to cool on its own or use a wort chiller to speed up the process. 

I recommend this Northern Brewer Stainless Wort Chiller from Amazon. I like this chiller because it is easy to use and it comes completely assembled with tubing, wires, and clamps. All you need to do is drop it in the kettle a few minutes before you’re done boiling

6. Add Lactic Acid to Your Wort

Once the wort is at the right temperature for your lactobacillus culture, you must take one more step to prepare the wort before adding the culture. 

Lactobacillus lives in acidic environments, so you need to make your wort acidic enough for the lactobacillus can do its job. 

Add lactic acid to your wort little by little, using your pH meter to check the pH level after every addition. Stop adding acid when the pH is approximately 4.1. Typically, it takes approximately 20 ml of lactic acid to bring five gallons of wort to a 4.1. pH. 

7. Add Lactobacillus to the Wort

Now’s the moment you’ve been waiting for! It’s time to add the lactobacillus to your wort. You should use a culture of approximately 400 ml, but if you want to make your beer extra sour, you can add a little more. Stir the wort thoroughly as you add the culture. 

I recommend using a pure lactobacillus culture instead of grain that hosts lacto cells for better flavor. 

8. Seal Your Kettle

Once you’ve added the lactobacillus, it’s time to let it work its magic. Seal the kettle so it is completely airtight. High-quality kettles should be airtight with just their lid, but if you have an older kettle, you can use an extra cover on top to ensure it is properly sealed. 

My favorite homebrewing kettle is this KLARSTEIN Maischfest Beer Brewing Kettle from Amazon. This kettle has a touch panel with an LCD display where you can set the temperature, power, and cooking time. I also appreciate that it’s made with taste-neutral stainless steel.

You’ll need to keep the kettle at the right temperature. If you have a high-tech kettle, such as the one recommended above, you can control the temperature inside the kettle. 

Another way to keep a kettle at the right temperature is by utilizing an electric blanket and wrapping it around the kettle. Just ensure that you check the kettle regularly so it doesn’t get too hot.    

9. Check the pH Regularly

Usually, it takes approximately two days for the wort to be soured while using the kettle souring method. However, starting at twelve hours after adding the lactobacillus, you should start testing the pH level with your pH meter. 

When the wort reaches 3.0-3.5 pH, the kettle souring is complete! If you know what you want the beer to taste like, you can taste the wort to make sure it’s the right tartiness for you.

Some types of kettle sours, such as gose and Berliner Weisse, are more tart and therefore require a higher pH. You should wait until your pH meter reads 3.6 or more before stopping the souring process of these beer types.   

10. Boil the Wort  

Once the wort reaches 3.0-3.5 pH and you’re happy with the taste, you need to kill off the rest of the lactobacillus. To do this, boil your wort for fifteen-minute intervals. Heating the wort again destroys the lactobacillus, so it doesn’t keep making your wort sourer and sourer.  

11. Add Yeast and Hops

Now it’s time to add in your yeast and hops. I recommend using more yeast than you usually do for other kinds of beer—the cells have to work a little harder due to the acidity of sour beers.  

I also suggest using a strong yeast strain to combat the acidity. If you don’t use strong yeast, fermentation will still happen—it’ll just take longer than you’d probably prefer. 

12. Wait Until Fermentation Is Complete

Now, it’s time to wait again. Allow the beer to ferment until there is no more activity in the airlock. At this point, fermentation is complete, and the brewing process is over! 

If fermentation takes longer than you expected, don’t panic. When fermenting a sour beer, the yeast cells have to work against more acidity than in other types of beer. This slows down the process.

If the fermentation takes way longer than expected, it may be stuck. If you’re unsure, check out my article on six ways to tell if your fermentation is stuck.  

13. Bottle It Up

You’re almost done! All you need to do at this point is bottle (or keg) your beer, serve it to your friends and family, and let the compliments roll in. 

If you need bottles, I offer many suggestions in my article on the best bottles for homebrewing. You may also consider adding a personalized label to the bottles to ensure everyone knows who to thank.

My favorite bottles to use for homebrews are the Otis Swing Top Glass Bottles from Amazon. I like them because they are BPA-free, durable, and dishwasher-safe, so they’re easy to clean and reuse. I also like their simple but classy design.

What Is Kettle Sour Beer?

Kettle sour beer is a type of beer that gets its taste from lactobacillus, which is added to wort while it is in the kettle. The kettle is also known as a stainless steel mash tun. 

Adding lactobacillus to the wort quickens the souring process and sets apart kettle sours from regular sour beer, which is traditionally soured, fermented, and matured in wooden barrels. 

Lactobacillus is a live probiotic that changes sugar to lactic acid, giving the sour beer its signature tart flavor. For more information, check out my article on the history and ingredients of sour beer.     

Kettle sours tend to have bright colors and are more acidic than traditional sours, though their flavors are usually less complex than beer that is soured in barrels. 

Still, many homebrewers use the kettle souring process because it is much faster than traditional methods. Aging a traditional sour beer in a barrel can take multiple months or even a year to complete. 

Kettle souring also allows brewers to make different kinds of sour beer, such as a sour IPA, gose, or a milkshake sour. 

The following table outlines the key differences between kettle sour beers and sour beers: 

Characteristic Kettle Sour Traditional Sour 
Flavor Simple, tart, and acidic  More complex and nuanced, funky
Container Stainless steel kettle Wooden barrel 
Method Lactobacillus changes sugar into lactic acid  Aged in the barrel until the yeast and bacteria change the flavor 
Time Finished in 1-3 days Needs to age for several months, if not years 

Kettle souring beer is quick, but it isn’t easy. Sours are considered one of the most difficult beers to make. If you’re curious about what beers are the easiest to brew, I suggest watching my video on the topic: 

However, brewing a kettle beer is a great opportunity to experiment with flavors and create a truly unique flavor if you’re up for the challenge. Let’s take a look at how to do it:


Kettle souring beer may seem overwhelming at first, but as long as you follow the above steps, you’ll be able to create a delicious, tart sour in just a few days. 

About HomeBrewAdvice

Hello, my name is Simon. Together with a group of writers I write about brewing beer and making wine. We all share a passion for the great things in life, such as making stuff from scratch.

The business of HomeBrewAdvice is to bring you great information, stories and product reviews from brewing at home, and making wine

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