What is Kahm yeast? - The Ultimate Guide

Fermentation is a very popular topic among foodies who like to experiment with flavor.

However, most people do not fully understand the process and the signs of fermentation and how it works. The only thing that is usually said is that you have to add the vegetables in the brine and wait for it to be done. But there is much more.

If you’ve ever fermented foods in brine, you may have come across kahm yeast.

What is kahm yeast? Simply put, kahm yeast is a velvety white layer that forms on top of the brine once the fermentation process has started. Don’t worry! This type of yeast is completely harmless and is considered common in home brewing projects and is not a cause for alarm. 

Most people think that their brine has gone bad after seeing kahm yeast, but the truth is that this type of yeast is not dangerous and does not endanger the fermentation process or you.

Of course, sometimes kahm yeast can also be mistaken for mold, which is obviously bad. Read on to learn more about what kahm yeast is, why it forms, how to prevent it, and how to tell it apart from mold.

The basics of fermentation

Fermentation is arguably as old as civilization. Human beings have been fermenting food and drink for centuries, and it’s only relatively recently that the average citizen has come close to this secret treasure box that reveals so much flavor.

The concept of fermentation is pretty straightforward: you basically let things go “bad”, but in a good way! Let us explain it to you.

When something “ferments,” it undergoes chemical changes that affect its color, texture, and most importantly, its flavor. 

This occurs with the help of bacteria that consume the food, releasing enzymes on a microscopic level and converting the sugars in the food into something that helps create much more flavor than it originally had.

We are surrounded by bacteria, and while most bacteria have a bad reputation, some are good for you. In fact, bacteria is the reason you can have cheese, sourdough, yogurt, and of course, fermented foods. 

Fermentation can also be called “lacto-fermentation”. You may see the word “lacto” and think it has something to do with dairy. Think again.

It is actually short for lactic acid. This compound is naturally present and is found in all organic matter. So what do bacteria and lactic acid have to do with kahm yeast? All.

The free bacteria, more specifically the Lactobacilli bacterium, can be considered as lactic acid producing factories.

This bacterium works by converting glucose from food into lactic acid, which in turn changes the texture, appearance and flavor of the ferment.

Fermentation occurs in the absence of oxygen, so it is necessary to immerse the food in brine or it will spoil when it comes into contact with air.

This process also encourages the growth of kahm yeast. We’ll talk about this again in a bit.

Once fermentation begins, the bacteria multiply as they continue to feed on the glucose in the food.

This happens gradually and you can see it happen over the course of a few days or weeks, depending on how you have prepared the brine and what you are fermenting.

In the end, you basically intervene in this process and stop it from moving forward. So you’re left with an abundance of bright, flavorful fermented foods and beverages. 

Pickles, kombucha, kimchi and much more. delicious!

The fermentation process and how Kahm yeast is produced

There are many ways to ferment food, depending on the recipe you’re looking at. For example, kombucha is a form of fermented tea and will be made differently than pickles.

We’ll look at one of the easiest ways to ferment vegetables, which is to find the exact salt content needed to create the brine for any intended vegetable or food.

But if you don’t want to do too much research, there is an approach you can use.

The following steps and formula can help you calculate the amount of salt needed for the brine:

1. First, calculate the weight of the vegetables and water in grams, add both figures, and then multiply that number by 2% or 0.02. This will give you the exact amount of salt in grams needed for most vegetables.
2. If it is about cucumbers or vegetables that are more prone to mold, you can use this same formula but with 3% (vegetable weight + water weight) x 3% or 0.03.

Now after this initial process of brining to ferment is normally when the kahm yeast will start to form over time.

You may start to notice the brine become a bit cloudy over the next few days. This is a sign that fermentation has started and the bacteria are doing their job. After a few days, you may start to notice a white coating on top of the brine.

As we’ve already said, this white coating is kahm yeast and it’s a by-product of the fermentation process , and it can mean something has gone wrong, but don’t worry.

There is a fact: you cannot always ferment food perfectly. There will always be some variable that causes a slight discrepancy. However, this is considered very common in the fermentation world.

Kahm’s yeast appears as a white film that may or may not have bubbles. Kahm’s yeast will look like a layer of spider web laid over your brine.

It has a smooth, velvety texture, and the yeast will also move with the brine if you tilt the container.

Why Kahm yeast is formed

There are many factors that come into play when fermenting food and inadvertently producing kahm yeast. Some of them are

1. Temperature
2. Cleaning
3. type of vegetable
4. How much the vegetable is submerged

Any number of things can trigger kahm yeast production, so the best thing you can do is minimize or prevent it.

Kahm yeast, although considered harmless, should not be encouraged for a number of reasons.

Some people don’t like the smell of kahm yeast brine and others just don’t find it appealing.  The good news is that you can easily pick up the yeast since it sits at the top of the brine. 

Once you’ve removed the top layer, you can carefully mix the brine in and you’re done!

Kahm yeast is harmless to humans as, unlike mold , it is not toxic to us. But it influences the appearance and taste of the ferment.

So most knowledgeable people would decide to keep part of it, all of it, or none of it. Meanwhile, the uninitiated or uninformed might think their brine has gone bad and throw it away.

how it smells and tastes

Kahm yeast smells, well, yeasty . It has a very distinctive smell, and once you get rid of it, you can compare it to the actual smell of the brine to see what the difference is.

Some people may even leave the yeast in place for its taste. Of course, it’s most likely an acquired taste for some people.

If Kahm yeast is present, the surface of your brine should be completely white, with a webbed, velvety texture. Sometimes there may be even small and large bubbles, but the entire layer should look the same.

If you want to go a step further to confirm if your ferment is safe to consume, you can check the pH of the brine. As long as it’s free of mold and the pH is 4 or below, you should be fine. 

How to Prevent Kahm’s Yeast

Preventing this type of yeast requires you to cover some basics.

First, you will need to make sure that you prepare the brine properly and that the salt content is as required (you can also refer to the formula above). Also, you should store the container in a cool, dry place.

Be sure to clean the container well before preparing the brine. Use soap and hot water to clean the inside and outside of the container.

Don’t forget to clean the lid as well. Temperature plays an important role in the production of kahm yeast, so you should also be careful where you store the container.

You will also need to properly submerge the vegetables so they are not exposed to air.

You can do this by placing a small weight on top of the brine or a bag filled with water to ballast the floating vegetables. Again, clean everything!

Of course, sometimes things go wrong even when you do everything right, which is why fermentation failure is so common at home. Perfect fermentation requires industrial-grade precision that home kitchens lack.

The only thing you can do is minimize the production of this yeast, and who knows, you might be able to keep it at bay.

There are too many factors that determine the production of kahm yeast, so you just have to strive to follow the best practices for a perfect or near perfect fermentation.

Of course, do not be scared if you end up seeing it!

Kahm’s Yeast vs. Mold.

Although kahm yeast is not dangerous, mold is.

The important thing is to know how to differentiate kahm yeast from mold. Fortunately, this should be easy, since molds have very different characteristics.

For example, mold has a distinct fuzzy texture and often shows different colors. 

Most types of mold are green in color, while others can even be yellow or any other shade. Sometimes mold can even appear light gray or whitish.

This is where it becomes slightly difficult to tell it apart from kahm yeast.

Luckily, you have other measures to determine and identify mold. For example, you should always look for signs like a fuzzy texture or musty odor, or even inconsistencies in the top coat.

Again, kahm yeast looks like a thin, velvety white film, while mold looks fuzzy, clumped, green, or any other color.

Mold is toxic to humans and is the result of bad bacteria taking over the fermentation process. The result is an unpleasant smell and taste, not to mention that it can make you sick.

We strongly recommend that you check the brine carefully and if you can’t tell it apart from the kahm yeast, it’s better to start over than risk contaminating yourself and getting sick.

Mold will always form when brine is not properly prepared and stored, and it can also be a result of spoiled vegetables. While kahm yeast seems harmless, mold can almost always be detected.

This is because you are more likely to see and recognize mold in your environment than kahm yeast.

The type of mold that develops on brine is pretty much the same as you would find on other organic things like bread, fruits, and vegetables.

Mold has a fuzzy or fuzzy appearance, with small fur-like bumps of different colors, while kahm yeast is airy, velvety and usually just a thin film, which can also appear as “broken islands” on the brine.

Of course, always remember: when in doubt, throw it away! It will take some time and practice for you to be able to make an informed and calculated judgment before disposing of your brine.

This can only come from experience so we encourage you not to let kahm yeast or mold get you down!

The result of fermentation will always overcome any setback. If you don’t ferment your food yet, we highly recommend you give it a try. It will unleash a world of new flavors you didn’t know existed in everyday foods.

Related questions

Now that we’ve gone over what kahm yeast is, let’s take a look at some related questions!

Is kahm yeast safe to consume?

Yes. Kahm yeast is non-toxic and safe to eat as long as it does not contain mold.

Kahm yeast is consistent in its texture and is usually white, while mold is often fuzzy in texture with variable colors. Always make sure to check the ferment before consuming it.

Kahm yeast will never make you sick as it does not contain bad bacteria, but if it is contaminated by mold, there is a high chance that it will make you sick.

The best way to treat kahm yeast is to discard it and check the brine periodically.

If you see any signs of mold, throw it all away, clean it up, and start over. 

Where can I buy kahm yeast?

You cannot buy kahm yeast, as it is usually a byproduct of fermentation. Kahm yeast has little or no use in food. Some people like its taste, while others dismiss it because of its smell and appearance.

Can kahm yeast be used in cooking?

No. The kahm yeast is usually discarded or mixed into the brine. It has no culinary applications, apart from its use in fermentation.

Kahm’s yeast is the result of something gone wrong in the fermentation process, but is considered to be within the acceptable range of error when fermenting foods.

As long as your brine doesn’t have any signs of mold, you’ll be fine. You can even collect the yeast and remix the brine. You may need to keep doing this until the fermentation process is complete.

Is kahm yeast a sign of bacteria?

Kahm yeast is produced by good bacteria that ferment the vegetables in the brine.

The gases and by-products that are released due to this process collect on top in the form of kahm yeast, which is why you may find the yeast to have bubbles and a velvety texture.

You can remove the yeast if you don’t want it. While it is true that kahm yeast is a sign that something has gone wrong in the fermentation process, it is completely safe and is also common in home fermentation projects.