SCOBY Mold: What It Is, What Causes It, and How to Deal With It

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Finding mold on a SCOBY is every homebrewer’s nightmare. When you brew kombucha at home, your SCOBY is an integral part of the journey, and the smallest amount of mold can hurt the entire process. Understanding what causes SCOBY mold and how to handle it is vital.

Can a SCOBY Grow Mold?

A SCOBY can grow mold if proper measurements and caution are not taken during storage or brewing. Like bread that produces moldy patches, mold spores can grow on a kombucha SCOBY.

A SCOBY, or symbiotic culture of bacteria and yeast, is a living culture of microorganisms and bacteria. The bacteria and yeast feed off the sugar in the sweet tea and ferment it into alcohol, acid, and carbon dioxide to create kombucha.

Mold reproduces by releasing tiny spores that float through the air and land in different locations. If they land on a damp surface, they will begin to build colonies. A moldy SCOBY may contain contaminants that can compromise your entire batch of kombucha. Kombucha mold should not be ingested, as it can cause illness or allergic reactions.

What Does a Moldy SCOBY Look Like?

The molding will almost always occur during the first fermentation process. If you are a first-time brewer and are unsure what a moldy SCOBY looks like, be aware of the following:

  • Fuzzy or dry spots on the surface: If your SCOBY begins to grow fuzz or you see dry areas, this is a good indication that your SCOBY has grown mold. Because mold needs air to survive, it will always form on the surface of your SCOBY near the top of the brewing vessel. If you notice anything underneath your SCOBY or floating in your kombucha, it is probably yeast particles, not mold.
  • Circular patterns: Generally speaking, mold will grow in clumps and circles, making it easier to identify.
  • Discoloration: Kombucha SCOBYs are typically brown or tan, so if you see white, blue, green, or black, this could be mold. White may be difficult to determine because not all white spots on your SCOBY are mold, but you should be able to tell by using the other determiners from this list.
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Various colors of mold

3 Main Causes of SCOBY Mold

There are multiple reasons mold could grow on your SCOBY, but here are the most common:

1. The brewing temperatures are too cold

If you are brewing your kombucha in temperatures below 65 degrees Fahrenheit, your fermentation process will slow. Fermentation produces acidity that keeps mold away and maintains a healthy SCOBY. You should always keep the temperature in the mid-70s for successful kombucha fermentation.

2. Brewing with flavored tea

If you introduce oils and outside flavor compounds to your kombucha during the first fermentation, the environment will be altered, which can harm your SCOBY. Avoid using flavored teas for your homebrew unless they are organic and free of additives. Your best bet is to use natural green or black tea for the first fermentation process and add flavors during the second fermentation.

3. Not using enough starter liquid

If you do not have enough starter tea, the quality of your kombucha will be diminished. You should always save at least two cups of starter tea from the first fermentation when taking out kombucha for the second fermentation. This will ensure you have enough starter liquid for a new batch and keep mold away from your SCOBY while it rests.

Can You Clean Mold Off a SCOBY?

If your kombucha culture has mold, you cannot clean it off. Once it has begun to form, it will continue to grow back, even if you think you have removed it.

What Do You Do If Your SCOBY Has Mold?

If you notice that your SCOBY is growing mold, you should discard it immediately. Additionally, discard any homemade kombucha tea made with the SCOBY. Then, you must disinfect your brewing vessel and any other tools used in your brewing process.

If you’d like to continue brewing kombucha, find a new SCOBY.

How to Prevent Mold From Growing On a SCOBY

  • Use enough starter liquid from a SCOBY hotel or other starter tea.
  • Use heating methods (like a heating mat) during colder months.
  • Don’t place houseplants in the vicinity of your brewing station.
  • Ensure the kombucha can adequately breathe during the first fermentation.
  • Never expose your brew to cigarette smoke.


Margaret has been drinking kombucha for its health benefits since 2010. Not only does she love drinking it, but she also enjoys brewing her own homemade booch. Her favorite combination so far is mint-strawberry, but she is always experimenting with new recipes.

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