How To Spot Mold vs. Kham Yeast on Kombucha and How To Prevent it

Is that mold on my kombucha? It is a common question from people new to making kombucha. Here is some information so you can tell if your kombucha is safe to drink or not.

When you are new to brewing kombucha or any fermented drink for that matter, the first time you see the fermentation process take place, it can look a little bizarre.

Homemade kombucha requires a little effort and a watchful eye to get the desired results. There are a few ways it can go wrong, and one of the biggest problems is finding mold on your kombucha.

Mold on kombucha can be spotted by looking for blue, black, green, white, or tan spots that appear to be dry and fuzzy. Good kombucha growth will be wet, not dry. Mold will also only appear on the surface layer because it needs air to survive. You will not see mold submerged in the kombucha.

Mold is a real fear among people who make homemade kombucha, but in reality, it does not appear very often. Usually, new kombucha makers are just confused as to what mold is and what is just a regular part of the kombucha SCOBY (symbiotic culture of bacteria and yeast).

You must learn to tell the difference so that you don’t end up throwing out a good batch. It will also be helpful to know what you can do to prevent mold from growing in the first place. That way, you know what to look for and how to prevent it from growing.

Identifying Mold

As mentioned above, mold has a few general characteristics which can help you identify it. To start, think of the mold you have seen throughout your life, the little fuzzy circles you’ve seen when bread is left out too long or you’ve forgotten about the cheese in the bottom of the refrigerator. Mold on your kombucha will look just like that! It is a little bit different though because most foods are kept in sealed containers. Mold needs air to live, and there is not any air under the liquid line of your kombucha, and so any mold that does appear will be right there on the top surface, so you should notice it quickly!

Kahm yeast looks very similar to mold and has caused a lot of people to throw out a good batch of kombucha. Since this is a common problem, let’s look at the differences between Kahm Yeast and mold. Each has similar attributes, but they still have differences that can be identified if you know what to look for.

Characteristics of Mold	Characteristics of Kahm Yeast
Fuzzy and Fluffy	Creates a film on the top
Multi-Colored (blue, grey, black, or white/tan)	White or Cream Colored
Raised	Connected, or Stringy (looks like pulled apart dough)
Starts out as just spots before forming a thick layer	Thin Layered
Looks Dusty	Trapped Air Bubbles

the start of mold growing on kombucha drink — the start of mold growing on kombucha – photo credit

green fuzzy mold growing on homebrew — fuzzy green mold growing on homebrew, similar to kombucha –photo credit

kahm yeast on kombucha — Kahm Yeast on kombucha – photo credit

DO NOT sniff for mold (even though Kombucha already has a unique smell) becasue sniffing it will actually cause the mold spores to come right up into your nose, so using your eyes is the best option.

If you do find mold on your kombucha, it is best to throw out the whole batch. This is the best practice because even though mold will only grow on the surface, it releases a ‘stem’. This means that bacteria from the mold has penetrated the surface and can cause your kombucha to taste off. It also has the potential to make you sick if you drink it.

Finding Kahm Yeast is totally normal and it doesn’t mean you need to throw it out. Many people still throw out batches with Kahm Yeast anyway because it can change the taste of the brew. However, Kahm Yeast mixtures are totally safe to eat, so in terms of health, you’ll be fine.

In summary, to identify mold, look for the circles of fuzz with lots of colors. If you are not sure what is forming yet, give it a day or two to see if the growths get bigger and easier to identify. If you let it grow, you’ll also become better at identifying mold vs Kahm Yeast.

Preventing Mold In Kombucha

Mold can be devastating if you are just starting on your experiments of making kombucha on your own. It might happen occasionally, but there are a few things you can do to try and prevent mold from growing. Don’t be too devastated if it takes a few tries.

Part of the process of learning how to make kombucha is trial and error, so take your time and make sure you always wait a couple of days for the weird formation to further develop before throwing it out.

Users on Reddit.com suggest a variety of ways to prevent mold from growing in your kombucha. These suggestions are:

“Make sure your starter liquid is strong (acidic) enough.” Source
“Adding a little white vinegar can help prevent mold.” Source
“Adding the stronger, more vinegary fluid from the SCOBY hotel would lower the pH more to help prevent molding.” Source
“Give everything [jars and other equipment] a good cleaning of course (I just run my stuff through the dishwasher first, some people will use a sanitizer like star san).” Source

These suggestions are some of the most common ones found, and many people have been able to brew their own mold-free kombucha using these tips. Cleanliness is obviously very important, as it will ensure that mold spores aren’t present before you even begin the process. Don’t use dirty scrubbers or rags because these can introduce mold.

Clean everything really well with hot water before you begin the process so that you can ensure you start with a clean slate. This step will also help you narrow down how and when the mold was introduced.

You can also prevent mold by placing your kombucha in the right area. If your kombucha mixture is sitting right next to the trash can, you are bound to get some airborne mold spores in there. Mold spores can also come from unwashed fruits and vegetables, or other nearby kombucha or fermentation mixtures.

If you are brewing with a plastic jar and consistently get infections, it is possible that the container has some minor scratches and is harboring contaminants.

In this case, I recommend replacing your jug with a glass one.

Always use the best sugars and teas, because they will improve the overall quality of the mixture. Make sure that the mixture is acidic, and if necessary, do some pH testing to ensure it is on the lower end of the scale. The lower it is on the pH scale, the less likely it is to develop mold.