Moldy Kombucha: What to Look Out For and What Causes It

Kombucha mold is an overgrowth of fungus in your brew that requires immediate attention. There are several reasons why kombucha brewers may discover mold in their tea. Luckily, there are also several ways to prevent moldy kombucha. 

How Do You Know If Your Kombucha Is Moldy?

Mold develops on top of your brew, where the sweet tea and the SCOBY are exposed to air. Your kombucha is most at risk for mold during the first seven days of the first fermentation. After seven days, the pH of your brew should drop, and the high acidity level will prevent mold formation.

Kombucha mold looks like mold on other food (bread, fruit, etc.). Mold spores are usually located on the top of your kombucha tea. They are typically circular, fuzzy, and gray, white, brown, blue, or black.

Mold Look-alikes

First-time brewers often confuse the following processes for signs of mold; however, they are completely normal:

• As your tea cycles through the fermentation process, you should see white blobs on top of your brew. After 5-7 days, these spots grow into a pellicle—what most brewers call a baby SCOBY. As your tea continues to ferment, this baby SCOBY gets thicker.
• You’ll also likely see bubbles, signifying the beginning of carbonation. During the first fermentation, brown bits of yeast begin to form. These yeast strands are stringy and either attach to the SCOBY or float in the bottom of your brew.
• Formation of the pellicle and yeast strands means that your homemade kombucha is fermenting properly and your SCOBY is growing. The more you homebrew, the more familiar you’ll be with the brewing process. You’ll be able to distinguish yeast strands or SCOBY formation and mold.

How Do You Remedy Moldy Kombucha?

You cannot remedy moldy kombucha.

If your kombucha brew molds during the first fermentation, your kombucha SCOBY may be contaminated. But even if you don’t have a moldy SCOBY, it’s still possible the SCOBY has some mold spores. Neither your kombucha tea nor your SCOBY is safe to use.

What To Do If Your Kombucha Has Mold

If your kombucha has mold, follow these steps:

• Dump out your batch. It might be tempting to try to save your kombucha—especially the first time you discover mold. However, if you try to save any part of your brew, you’ll risk your health and contaminate future batches.
• Clean your equipment and get a new SCOBY. Make sure to sanitize your brewing vessel and any other tools you use to make your kombucha tea. You might consider sanitizing cleaner to disinfect your supplies thoroughly. You can also sterilize with white vinegar and hot water.

You must start your kombucha brewing process entirely over so you don’t carry any mold spores into future batches.

Can You Drink Moldy Kombucha?

No, do not drink moldy kombucha. It can make you very sick. If you see mold in your kombucha, throw your whole batch away!

5 Ways To Prevent Mold From Growing in Kombucha

Kombucha is full of living organisms and is at risk for mold growth. Following proper brewing guidelines and keeping your brew comfortable can go a long way in preventing mold from growing.

Here are five ways to help prevent mold from growing in your kombucha:

1. Use the correct sugar-to-tea ratio. A gallon batch of kombucha needs 1 cup of sugar. Use real cane sugar when you brew. Kombucha will not ferment properly if you use artificial or low-carb sweeteners.
2. Use the correct amount of starter tea. The starter liquid helps jumpstart your batch of kombucha. It helps it achieve the proper acidity level, making it safe to drink. Using too much or not enough starter liquid will throw your kombucha tea off balance. Use two cups of starter tea for each gallon batch of kombucha. A SCOBY hotel is a great place to grow strong starter tea.
3. Brew your kombucha between 68 and 78 °F. If the temperature of your kombucha tea drops below 65 °F, your brew will ferment too slowly and could turn moldy. In the summer, you can keep your brew at room temperature. In the winter, you may need to purchase a heating wrap.
4. Make sure your brewing vessel has good airflow. Avoid placing your kombucha in a cabinet where the air is stale. Set your kombucha tea on the counter and cover your brewing jar with cheesecloth or a coffee filter. You want to ensure that fruit flies can’t get in but that your fermenting tea can breathe.
5. Keep your kombucha away from houseplants. Sometimes indoor plants harbor mold or attract flies—neither is good for your kombucha!

Can Mold Grow During the Second Fermentation?

Kombucha typically goes through two fermentations. Mold could grow during the second fermentation but is far more likely to develop during the first fermentation.

When you combine the ingredients for the first fermentation, the tea has a starting pH of around 4.5. As the sweet tea ferments with the SCOBY, the pH drops between 2.5 and 3.5. When bottled kombucha enters the second fermentation, mold should have difficulty growing because of the low pH.

Before beginning your second fermentation, ensure your bottles are clean and sanitized. Also, sanitize equipment to transfer your kombucha between your brewing vessel and glass bottles. Check fresh fruits or herbs for signs of mold.