What Is Krausen? | A Guide to the Beer Fermentation Process

Looking for a sign that your beer is on the right track in the fermentation process?

Enter krausen — it gives you a signal that fermentation is happening, and if the bubbles subside, it means the process is complete!

With this article, you will surely learn more about what krausen is and what it signals in the whole fermenting process of making beer.

What Is Krausen?

The Merriam-Webster  dictionary describes the term krausen as a transitive verb that means adding fermenting wort into beer.

This German word, kräusen, means to curl back. Also, it has been widely used as a noun for the fermenting wort itself.

In simpler words, krausen is a foamy head you usually find when an actively fermenting beer inside a fermenter is at its peak. 

It is common mainly when the active yeast interacts with fermentable sugars, carbon dioxide, and other brewing essentials.


When krausen is visibly evident (similar to the picture above), the yeast cells are in good condition. Additionally, as the krausen settles, it signifies that your fermenting beer is ready.

Moreover, its foam head is composed of living and dead yeast cells as you pitch yeast into the beer, proteins, and hop particles or resins from wart boiling, and it can be in different colors – brown, off-white, or white.

How Do You Pronounce Krausen?

Besides knowing what it is, it is equally important to understand how to pronounce the word krausen correctly.

On a dictionary basis, it is pronounced as ˈkrȯizᵊn. According to the University of Pennsylvania’s phonetic symbols, the au and the (in “sen”) are verbalized like the Korean eo. Of course, the s is pronounced as z.

However, krausen is spoken differently in German without the /r/ sound, as depicted in this pronunciation dictionary.

What Is Krausen Made of?

Krausen does not happen in a snap. It has components that contribute to how low or high it can be. 

For krausen to show up on your brew, it would take a mixture of these factors:

  • Alive and dead yeast cells
  • Hop particles
  • Wort protein
  • Grain
  • Sugars
  • Carbon dioxide

High and Low Krausen

Aside from varying colors, a layer of krausen that adheres to the sides of a fermenter also differs in how high or low it can be.

On the one hand, low krausen indicates the primary stage of fermenting wort due to the yeast starting to be active.

It involves a low and stable thin layer of white yeasty foam that later turns white to brown as the carbon dioxide comes in contact with the wort.

On the other hand, having krausen high is a good indicator that the beer is at the peak of fermentation and still going through it, which means that it is not yet ready.

With a high krausen, you can expect that the peaks of some beer (or all) will have a sticky texture and a bitter taste.

However, as it goes back to being a low krausen when it subsides, the foam will stick onto the beer fermenter’s sidewalls, which is why the bitterness detaches from the beer itself.

Nonetheless, a low krausen after a high one will mean that the beer is done fermenting.

How Much Krausen Is Normal?

In producing alcohol, you will not always use the same beer and yeast, unlike commercial brewers who must have the same beer in every batch.

This factor will surely make a difference in terms of the krausen level. There can be krausen as low as half an inch, 1 1/2 inches, or as high as 5 inches. All of these levels are normal.

The differences in how low or high a krausen can be dependent on the following factors and components:

  • Yeast activity
  • Yeast selection
  • Beer
  • Temperature
  • Grain bill
  • Measured amounts of sugars 
  • Mashing at the start of production

When Does Krausen Fall or Go Away?

When there is a rise, there is also a fall.

In the brewing process, krausen will fall from the peak of the fermenting beer to the bottom of the fermenter, approximately at most, after three weeks

However, some krausen falls within one to two weeks and will still signify that your fermentation is complete. 

Yet, you can always check it thoroughly by gravity reading using a hydrometer.

Is Krausen a Sign of Fermentation?

Yes, krausen is a sign of fermentation as it signifies that your yeast activity is going well, especially when the krausen is high. Most of all, it will signal you that your beer is ready in no time as soon as it starts to subside.

However, it is not the only sign of fermentation as these factors may also reveal beer fermentation:

  • Yeast clumping before the actual krausen
  • Carbon dioxide bubbles over the wort
  • Trub or the hop particles and other materials at the bottom of a fermenter
  • Final gravity reading from a hydrometer

Pros and Cons of Krausen

To understand “what is krausen?”, we will present you the pros and cons of having a layer of krausen on top of your beer:


  • It will determine if you have active yeast or the contrary
  • It will signify that you are on the right track regarding the fermentation process
  • It will indicate the fermentation status of your beer
  • It is a natural part of the brewing process
  • It will produce a more consistent beer
  • It will remove unnecessary elements from your wort
  • It will take off flavors of bitterness from your beer
  • It will introduce new and healthy yeast to the fermentation through krausening

QUICK FACT: The Krausening process means to naturally carbonate beer by adding wort into a tank of fully-fermented beer. 


  • Racking or transferring your beer may become disorganized because of the foamy feature
  • It may limit the hop particles and aroma from the beer
  • Krausen blowouts are normal, but they tend to be messy
  • Blowouts in krausen can also cause damage to your fermenter

However, do not worry that much because, in the following sections, we will give you tips on preventing blowouts on your krausen!

How to Prevent Krausen Blowouts

A blowout in the fermenter usually happens when the krausen goes out of proportion as the yeast activity becomes too much.

This leads to producing too much foam and popping off the airlock of the fermentation tank as it hinders the air from going out through the carboy airlock.

It is a common phenomenon when the fermenter is too tiny for the mixture of fermented beer, or you are using a traditional carboy airlock.

It would be best if you use a blow-off tube to prevent a krausen from a blowout.


A blow-off tube is a plastic tubing that most homebrewers use, where the end of the cylinder is connected to the cover of the fermentor in place of an airlock. At the same time, the other end is sunken in a spare jug, container, or bottle with sanitary solutions.

This blow-off tube will help you prevent a messier station and can even save your entire fermentation tank from mishaps and problems, as blowouts can damage your fermenter.

Moreover, another alternative is an anti-foaming agent or foam inhibitor like the FermCap-S.

You can use two drops of the FermCap-S on your fermenter or carboy at the beginning of your fermentation. However, this alternative will cost you more than the blow-off tube.

Frequently Asked Questions

We know you want to know more about krausen to have good fermentation dynamics on your next batch.

Well, fellow brewers, we got your frequently asked questions covered in this section:

Should I Remove Krausen from an Active Fermenting Beer?

You can remove the krausen present in your brew or fermenter through the blow-off tube method mentioned earlier to prevent blowouts, particularly when you have a smaller fermenter.

Doing this will also add to the flavor and texture of the beer recipe.

However, some brewers will just let the krausen fall on its own, as it is a sure sign that the fermentation has ended.

What Does Krausen Look Like?

Krausen looks like a creamy rocky head or a thick layer of foam that builds up on top of a fermenting beer and varies in off-white, white, or brown colors. 

Some krausen present a green color from the carbon dioxide that krausen generates in a secondary fermentation with added sugars.

Also, while in the brew, a krausen may present small or large bubbles depending on its ingredient proportions and original gravity.

Can I Rack Beer With High Krausen?

Yes, you can rack a beer with high krausen. Racking a beer with high krausen means moving it from its original fermenter or barrel to a new fermenter.

Yet, before you rack a beer with high krausen, be reminded of these facts as you watch your beer brew:

  • High krausen is a sign (but not the only sign) that your beer is still undergoing fermentation
  • It will take 5 days to finish fermenting, 14 days for a complete fermenting process, and at least 21 days until the high krausen lowers itself, combining naturally with the beer
  • It is better to rack it when the krausen starts to subside

So, think twice (or thrice) before racking your beer with high krausen.

Why Do I See Plenty of Krausen But No Airlock Activity?

Having no airlock activity despite krausen being present is nothing to worry about, as this can still mean you have healthy yeast.

In fact, most brewers use an open-lid method since the krausen is thick enough to limit the entry of oxygen.

Nevertheless, there are many causes for having plenty of krausen present in your fermenter but with little to no airlock activities. 

One of these reasons is that maybe there is a leak in your glass carboys or plastic airlock. To remedy the leak, you can follow these steps:

  • Push the airlock or the lid down
  • Tighten its closure
  • Replace the plastic or carboy airlock

Final Words

We hope you now know what krausen is and what it does in the fermentation and brewing processes.

general rule to remember for brewers like you:

When krausen rises, your yeast is actively performing, and fermentation is at its peak. Not too many weeks after this, as the krausen falls, it will signal you that the fermentation is complete.

Also, as brewers, never forget to ask for help from a gravity reading hydrometer to know the content of the wort before and after brewing and if the process has been completed by getting the final gravity.

Now, everything is settled on the question, “what is krausen?”

So get your yeast, wort, brewing equipment, and other essential components to start your brewing or fermenting process. 

You’ll have your alcohol ready in no time!

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