Since kombucha and kombucha SCOBYs can look weird due to yeast and bacteria growth, it can be hard for beginning brewers to identify what’s normal and what’s mold. I had the exact same problem when I began brewing. So what does kombucha mold look like?
Moldy kombucha is very rare, but if there is mold on a SCOBY, it will always be on the surface and have a dry and fuzzy texture. Mold also usually develops in a circular shape and can be white, green black or blue. To avoid a moldy SCOBY, keep the acidity of your kombucha brew high, store it at 70-80 degrees fahrenheit, and use pure and organic ingredients.
In this guide I'll walk you through how to find out if your kombucha is moldy, give you 5 tips to help you prevent kombucha mold, and tell you what to do if your SCOBY does develop mold so you can feel confident about the health of your kombucha brews. Let's get started
What is Kombucha?
Kombucha is a probiotic drink made from fermented tea that has become quite popular in recent years due to its great taste and many health benefits such as improved digestion and gut health, detoxification, and immune system strengthening.
What is a SCOBY?
The SCOBY (Symbiotic Culture of Bacteria and Yeast) is a living culture of bacteria that is used to make kombucha. The bacteria and yeast eat the sugar and nutrients in sweet tea and ferment it into alcohol, acids, and carbon dioxide to create sour kombucha.
When most people speak of the SCOBY, they’re talking about the ¼ inch to 2 inch thick jelly-like disk of living bacteria that sits on top of brewing kombucha. This disk on the surface of the booch is actually called the pellicle.
The pellicle is a mat of cellulose, which is basically a bunch of sugar strung together by the bacteria. If you look at a pellicle through a microscope, you can actually watch the bacteria creating these strings of sugar. It’s pretty cool.
Technically, the pellicle is part of the SCOBY, but it’s not all of it. SCOBY refers to all the bacteria and yeast present throughout the kombucha, including that in the pellicle, but also that floating through the kombucha.
What is Mold?
Mold is a type of fungus that grows in damp environments. Mold can develop in bathrooms, kitchens, basements, crawl spaces, and on old food. Some people are allergic to mold which means that inhaling or eating it can lead to serious health problems. But even those without allergies will want to avoid eating mold since it can lead to nausea and vomiting.
What SCOBY Mold Looks Like
If mold is going to develop in your kombucha, it’s likely going to happen during the process of 1st fermentation, because once the kombucha is in the 2nd fermentation and has been bottled, its high levels of acidity will prevent mold from growing.
So what does kombucha mold look like? Here are a few descriptors you can use to identify mold in your booch.
1. Mold always grows on the surface.
Because mold is an aerobic being (it needs air to survive) you’ll only find it on the surface of kombucha. This means that anything under the SCOBY or floating in the liquid of the kombucha is not mold.
2. Mold’s texture is dry and fuzzy.
Mold is made of tiny hair like structures known as hyphae that are fuzzy to the touch. Knowing this, we can rule out any smooth and moist parts of our SCOBY as not moldy.
3. Mold develops in circles.
Mold usually grows in clumps, circles, or rings.
4. Mold is an interesting bright color.
The SCOBY is usually brown/tan, so if you see colors of white, green, blue, or black, there could be mold developing. White is probably the hardest to define as mold but if you use the other identifiers in this list (is it circular? fuzzy?) you should be able to identify it as mold or not.
I Can’t tell if My Kombucha is Moldy
A lot of beginning brewers get the weird natural look of their growing SCOBY confused with mold. An important thing to remember is that MOLD IS RARE. Most of the time, if you're not sure about whether or not your SCOBY is moldy, it probably isn’t.
Another important thing to remember is that SCOBYs are like snowflakes, every one is unique. Your SCOBY may appear dark and rough, while your friend's SCOBY may look white and smooth. So just because your SCOBY look different than others does not mean it's moldy.
If you’re really not sure about whether or not your SCOBY is moldy, wait a few days. Either more mold will develop and it will become obvious, or nothing will change and you know that there is no mold growth occurring.
How do I Prevent Kombucha Mold?
The good thing about mold is that with the right preventative measures, we can almost always keep it from developing.
If you’ve had moldy kombucha in the past, this short list of tips below could prevent it from growing in the future.
1. Keep Your Brewing Kombucha at The Right Temperature!
If your kombucha brew isn’t kept at a temp above 65 degrees fahrenheit (18 degrees celsius), it is very likely to develop mold. This is because low temperatures slow down the fermenting process and make the bacteria culture in your booch inactive. And if the bacteria in your booch aren't active, the brew has no acidity in it to prevent mold or other bad microorganisms from developing.
The ideal range of temperature to keep your kombucha jar in is 75-85 degrees fahrenheit (23-29 degrees celsius). It’s usually easy to stay in this range in the summer, but “winter is coming” and if your kitchen isn’t heated enough, your home brewed booch could have some problems.
Wrapping your brew in a blanket or towel and placing it near an appliance in a warmer area of the kitchen is one way to keep your booch warm enough. But if you’re still having a heating problem and dealing with mold and ruined brews, you could save a lot of time and money by investing in a kombucha heater.
Kombucha heaters are heating pads made specifically for home brewing kombucha and allow you to control the temperature of your brewing booch to the degree. They’re also super energy efficient, so you can have one on 24 hours a day without worrying about your electricity bill running up.
Hemlock home brewing makes a really good quality heating pad for 1 gallon vessels. It has 3 temperature settings that allow you to configure the heat to exactly the level you need, and has a temperature gauge that makes it easy to know exactly how your booch is doing. Plus it’s Amazon Prime eligible. You can check out Hemlocks kombucha heating wrap on Amazon here.
2. Use Enough Starter Tea.
The whole purpose of starter tea is to give our brew acidity early on. If we don’t use enough starter tea, we have the same problem that we have if our brew is too cold: a low acidity and therefore no protection against mold growth.
I always recommend using at least 2 cups of starter tea per gallon of kombucha. If it's your first brew and you bought a SCOBY online, just use all the starter tea that it comes packaged in and you should be fine.
3. Use the Right Kind of Tea.
I’ve already written an article on the best kind of tea to use for the healthiest and best tasting kombucha which you can check out here.
A quick overview is that you should use pure, organic, caffeinated tea to brew your kombucha.
It turns out that the first time tea leaves are washed is when you brew them! This means that if the tea you use isn’t organic, pesticides and chemicals are likely going to end up in your kombucha.
Even if you’re not worried about consuming these chemicals yourself, you should be worried for your SCOBY. Because the SCOBY eats basically whatever you give it, if there are chemicals and pesticides in your tea, it’s going to eat them.
And because of how sensitive the SCOBY is, (even touching it with unwashed hands could damage it) if you give it something it’s not supposed to eat such as pesticides or chemicals, it’s going to die, or get weakened to the point where it can’t fight off mold growth.
The reason to use pure tea leaves to brew kombucha is that they will give you the cleanest flavor and most nutrients possible out of the tea. These extra nutrients are not only good for you, but will also be great for keeping the SCOBY healthy.
Another reason to use pure tea is that the chemicals in scented or flavored teas can hurt the SCOBY, leading to your kombucha tasting funny, the SCOBY dying, or your brew becoming moldy.
While organic and pure tea leaves will make better and healthier kombucha, they are optional. What’s not optional is that the tea you use to brew kombucha NEEDS to be caffeinated. Caffeinated tea is necessary because caffeine is one of the most important nutrients for keeping the SCOBY healthy.
4. Use Pure Sugar and Avoid Chlorinated Water.
Artificial sweeteners lack the required calorie based sugars your SCOBY needs for food. So using them in place of sugar will lead to your SCOBY dying of starvation. Use normal sugar.
Chlorinated water is in the taps of many homes in the United States, but chlorine isn’t good for the SCOBY, so I recommend using distilled water. You can pick up a gallon for cheap at almost any grocery store.
5. Keep Your Brewing Vessel Out of The Sun and Away From Moisture.
Your SCOBY can become damaged if stored in direct sunlight, and a moist environment is mold’s favorite place to form. A countertop away from windows in your kitchen or pantry is probably the best place to keep your brew. Just make sure the top is covered with a cloth to keep the bugs out.
If you follow these 5 tips, you should be able to keep mold away from your SCOBY forever.
You may be able to get away with not doing a few of these things right in a brew, just know that mistreating your SCOBY over time will lead to it slowly weakening until it's unable to fight off mold.
What to Do With a Moldy SCOBY
I know I told you it’s super rare that you get mold on your SCOBY. But let’s say that you did. The first thing you need to do if this happens is throw away your SCOBY and any liquid/kombucha it touched.
You can’t just peel off the moldy part of the SCOBY and save the rest because mold spores can be microscopic. If they’re in one place, the whole brew is contaminated.
After you dispose of the SCOBY and any contaminated liquid and the brewing vessel is empty, wash it thoroughly with soap and water like you would wash your dishes.
Once it’s cleaned with soap and rinsed, add a splash or two of distilled/pasteurized white vinegar (raw vinegar has its own bacteria cultures that will contaminate our brew) and swirl it around to coat all the interior of the jar. This process is known as “curing” and does two things:
1. Removes any soap left behind that could harm our SCOBY
2. Sets the pH of the jar to prevent mold and contaminants
After curing you don’t need to rinse the jar again, just plop in your SCOBY and starter tea and begin brewing again.
I know it sucks to have to start all over, but hopefully you can figure out what caused the mold and use the 5 tips above to figure out how to prevent it in the future.
Although mold rarely develops in brewing kombucha, it is something to look out for.
As long as you keep the acidity of your brew high, store it at the right temperature, and use the correct ingredients, you should never have a mold problem in your kombucha.
To learn more about how to tell if your kombucha is moldy or not, you can check out this great youtube video by You Brew Kombucha.
And if you want to learn more about kombucha, how it relates to your health, and even how to brew it yourself, check out the rest of my website!