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What Is Kahm Yeast? – The Ultimate Guide

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Fermentation is a niche yet popular subject among foodies who love to experiment with flavor.

However, most people don’t fully understand the process and signs of fermentation or how it works. You are only usually told to add vegetables in brine and then wait until it’s done. But there is so much more to it!

If you have ever fermented food in brine, then you may have come across kahm yeast.

What is kahm yeast? In a nutshell, kahm yeast is a white velvety layer that forms on top of brine after the process of fermentation has started. Not to worry! This type of yeast is completely harmless and is considered to be common in home-based fermentation projects and is no cause for alarm. 

Most people think that their brine has gone bad after seeing kahm yeast but the truth is, this type of yeast is not dangerous and it doesn’t 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 differentiate it from mold!

The Basics Of Fermentation

Fermentation is arguably as old as civilization. Humans have been fermenting food and drinks for centuries and it is only relatively recently that the average joe has gotten a whiff of this secret treasure box that unlocks so much flavor. 

The concept behind fermentation is pretty simple: you basically let things go “bad” – but in a good way! Let us explain. 

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

This happens with the help of bacteria that consume food, release enzymes on a microscopic level and convert the sugars within food into something that helps create so much more flavor than what you started with. 

We are surrounded by bacteria and while most bacteria justifiably get a bad rep, some of them are good for you. In fact, bacteria are the reason why you are able to have cheese, sourdough, yogurt, and of course, fermented food

Fermentation can also be called “lacto-fermentation”. You might look at 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 occurring and can be found in every organic matter. So, what do bacteria and lactic acid have to do with kahm yeast? Everything.

Free-range bacteria, more specifically, the Lactobacilli bacteria, can be thought of as lactic acid-producing factories.

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

Fermentation happens in the absence of oxygen, which is why you need to submerge food in brine or it will just go bad when in contact with air.

This process also happens to encourage the growth of kahm yeast. We will come back to this in a bit.

Once fermentation begins, the bacteria multiply, as they keep feeding on the glucose within the food.

This happens gradually and you can see it happen over a 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 progressing further. Thus, leaving you with a bounty of bright fermented food and drink that is packed with flavor

Pickles, kombucha, kimchi, and more! Delicious!

The Process Of Fermentation And How It Produces Kahm Yeast

There are a lot of 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 in a different way as compared to pickles!

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

But if you don’t want to get into a lot of research, there is a close approximation that you can use. 

The following steps and formula can help you calculate the quantity of salt required for the brine:

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

Now, after this initial process of brining in order to ferment is normally when kahm yeast will begin to form over time.

You may start to notice the brine get a bit cloudy over the next few days. This is a sign that fermentation has begun and the bacteria are doing their job. Once a few days have passed, you might start to notice a white layer on top of your brine. 

As previously mentioned, this white layer is kahm yeast and is a by-product of the fermentation process and it can mean that something has gone wrong – but don’t worry.

Here’s a fact: you can’t always ferment food perfectly. There is always going to be some variable that causes a mild discrepancy. However, this is considered to be very common in the world of fermentation. 

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

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

Why Kahm Yeast Forms

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

  1. Temperature
  2. Cleanliness
  3. Type of vegetable
  4. How much the vegetable is submerged

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

Kahm yeast, while considered to be harmless, shouldn’t be encouraged for different reasons.

Some people don’t like how the brine smells with kahm yeast and others just might not find it appealing. The good news is that you can easily scoop up the yeast since it sits on top of the brine

Once you have cleared the top layer, you can carefully give the brine a mix and you should be good to go!

Kahm yeast is harmless to humans, as in, unlike mold, it isn’t toxic to us. But it does play a role in how the ferment looks and tastes. 

This is why most knowledgeable people would either decide to keep some of it, all of it, or none of it. Meanwhile the uninitiated or uninformed foodies might think that their brine has gone bad and throw it away. 

How It Smells And Tastes 

Kahm yeast smells, well, yeasty. It has a very distinct smell and once you get rid of it, you can then compare it with the actual smell of the brine to know how much of a difference it makes. 

Some people might even leave the yeast in place for its flavor. Of course, it will most likely be an acquired flavor for some people.

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

If you want to go a step further in confirming whether your ferment is safe to consume, you can check the pH of the brine. So long as it doesn’t have mold and the pH is 4 or lower, you should be good

How To Prevent Kahm Yeast

Preventing this type of yeast requires you to cover a few basics. 

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

Make sure to clean the container properly before preparing the brine. Use soap and warm water to cleanse the inside and outside of the container.

Don’t forget to clean the lid as well. Temperature plays a big role in the production of kahm yeast so you should be wary of where you store the container too. 

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

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

Of course, sometimes things go south even when you do everything right which is why fermentation failure is so common at home. Perfect fermentation requires industry-level precision that home kitchens just don’t have. 

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

There are too many factors that determine the production of kahm yeast so you can just try your best to follow all the best practices for either perfect or near-perfect fermentation. 

Just don’t panic if you do end up seeing it!

Kahm Yeast Vs. Mold.

While kahm yeast isn’t dangerous, mold is.

The important thing is to be able to differentiate kahm yeast from mold. Thankfully, this should be easy since molds have vastly different characteristics.

For example, mold has a distinct fuzzy texture and will usually show different colors

Most types of molds have a green color while others may even be yellow or any other shade. Sometimes, mold may even appear to be light gray or whitish.

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

Luckily, you have other metrics to determine and identify mold. For example, you should always look for signs like a fuzzy texture or a rancid smell, or even the inconsistencies in the top layer.

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

Mold is toxic to humans and is a result of bad bacteria taking over the fermentation process. This results in a disagreeable scent and flavor – not to mention, it can potentially make you sick. 

We highly recommend that you carefully check the brine and if you can’t differentiate it from kahm yeast then it is better to start again than risk contaminating yourself and getting sick. 

Mold will always be formed when the brine isn’t prepared and stored properly and can also result from bad veggies too. While kahm yeast looks harmless, mold is pretty much universally detectable.

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

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

Mold looks hairy or fuzzy with small fur-like protrusions of varying color while kahm yeast is airy, velvety, and is usually just a thin film, which can also appear as “broken islands” on top of the brine. 

Of course, always remember: when in doubt, throw it out! It will take you some time and practice until you are able to make a knowledgeable and calculated judgment before discarding your brine.

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

The result of fermentation is always going to outweigh any setbacks. If you aren’t already fermenting your food then we highly recommend that you try it. It will unleash a world of new flavors that 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 a few related questions on the subject!

Is kahm yeast safe to consume? 

Yes. Kahm yeast is non-toxic and safe to consume as long as the yeast does not contain any mold.

Kahm yeast is consistent in its texture and is usually white while mold usually presents with a fuzzy texture with varying colors. Always make sure to check your ferment before consuming it. 

Kahm yeast will never make you sick as it doesn’t contain bad bacteria but if it is contaminated by mold then there is a good chance that it might make you sick.

The best way to deal with kahm yeast is to discard it and monitor the brine periodically. 

If you notice any sign of mold, please discard everything, clean, and start again

Where can I buy kahm yeast?

You can’t buy kahm yeast as it is usually a by-product of fermentation. Kahm yeast has little to no purpose when it comes to food. Some people enjoy its taste while others would just discard it because of how it smells and looks. 

Can kahm yeast be used in cooking?

No. Kahm yeast is usually discarded or mixed into the brine. It doesn’t have culinary applications other than its use in fermentation.

Kahm yeast is a result of something that has gone wrong in the fermentation process but is considered to be within the acceptable range of error while fermenting food. 

So long as your brine doesn’t have any sign of mold, you will be fine. You can even scoop up the yeast and mix the brine again. You may have to keep doing this until the fermentation process is complete. 

Is kahm yeast a sign of bacteria? 

Kahm yeast is produced because of the good bacteria that ferments the vegetable within the brine.

The gasses and by-products released due to this process accumulate 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 desire it. While it is true that kahm yeast is a sign of something that went wrong in the fermentation process, it is completely safe and is also common in home-based fermentation projects. 

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