How To Prevent Mold Growing On Your Kombucha
Unless you’re reading this article from inside a “clean room” in a hospital, nuclear facility, or semiconductor manufacturing plant, you’re currently surrounded by thousands of mold spores. They’re in the air, in the fabrics on the furniture, in the plaster on the wall and ceiling – they’re everywhere. Most of these molds are harmless, but some of them have the potential to colonize and develop into clusters that present health risks to humans (especially children and older adults).
Many of these molds are already associated with food, like the molds that grow on stale bread or overripe fruit. Some are essential to food production, in fact, such as the blue molds that give Roquefort cheese its distinctive flavor and appearance, or the molds that turn soybeans into miso paste. However, none of them are ones that you want contaminating your kombucha or spoiling your SCOBY (Symbiotic Colony Of Bacteria and Yeast).
To prevent mold problems when brewing kombucha, follow these simple tips:
Keep Your Equipment Clean
Everything involved in kombucha brewing should be clean: your equipment, the utensils, the plate you use to hold the SCOBY when you’re transferring it from one brewing container to another, your hands. Although you need to avoid using anti-bacterial soap, which will harm the SCOBY, you should scrub your hands well before touching the SCOBY, including under your fingernails. Rinse off any soap residue using filtered water.
When you clean your equipment, use hot water and soap, then rinse under filtered water. It’s a good idea to do a final rinse using a mixture of distilled vinegar and filtered water, to make sure all of the soap is gone.
If you use the same pot to boil the water for your sweet tea mixture that you used for cooking your dinner the night before, make sure it’s absolutely clean before you start. In fact, if you can use separate equipment for kombucha brewing you won’t have to worry about accidentally getting bits of leftover food mixed into your kombucha starter.
Use a clean cloth to cover the brewing container and make sure it’s tightly wrapped around the top of the container. Avoid using cloth that attracts lint, or that is made out of a fuzzy material that could drop particles into the liquid. The cloth should be tightly woven so that it keeps out airborne mold spores and dust particles as well as insects.
Keep Your Workspace Clean
Make sure all your work surfaces are clean, to avoid accidental contamination. It’s a good idea to keep the area clear of indoor plants, which often have excess mold buildup in the potting soil or on the leaves.
Many people find that they have problems with mold when there are smoke particles in the air where they are brewing kombucha, so avoid smoking. The smoke from cigarettes will change the pH of the kombucha tea, and leave it vulnerable to the mold spores. Smoke from cooking – especially fatty foods – will also collect on the top of the kombucha tea, and interfere with the flow of oxygen that the SCOBY needs to stay healthy.
While you don’t need to go overboard, use common sense when brewing. Don’t leave the SCOBY on the counter in reach of a curious dog or cat, don’t let your pet parakeet perch on the edge of the container you’re stirring sugar into, and don’t pick up a spoon to stir with out of the pile of dirty dishes next to your sink.
The clean workspace rule also applies to the place where you’re leaving your brewing container. Keep the brewing jar in a place that has good airflow, is free of dust, and has an even temperature and humidity.
Keep pH Levels Low
Make sure you add enough starter and/or vinegar to your sweetened tea to keep the pH low at the beginning of the brewing process. Many molds like the sugars in the tea just as much as the SCOBY does, and at the beginning of the brewing cycle, your SCOBY will not have had time to convert those sugars into acids that fight off the invading molds. Follow the correct brewing method for kombucha (LINK TO KB-Brewing-Kombucha-How-Much-To-Add) by using the right ratio of ingredients.
Keep Temperatures High
If the SCOBY and the liquid are too cool, the process of converting sugars to acids will go more slowly. This gives the mold more opportunities to grow. You need to keep the brewing container at room temperature, or an average of 75F. The temperature should not get below 65F or above 85F.
There are several ways you can keep your kombucha culture warm
- wrap a heating pad or heated blanket around the jar
- put the jar on or near something that is always warm, like the refrigerator
- use a heating mat inside a closed box or cupboard
If you live in a very warm environment, keep the kombucha cool by placing it in a dark cupboard that has good airflow.
NOTE: If your sweet tea is too hot when you add the SCOBY, you will kill off some or even all of the yeast and bacteria in the colony, and both the dead SCOBY cells and the sweet tea will attract mold. Make sure your sweet tea has cooled to room temperature before adding the SCOBY.
Use Quality Ingredients
If your water is contaminated, your kombucha will be, too. That’s why it’s best to use filtered or distilled water for brewing kombucha.
Use the best ingredients you can find. While you can use either loose tea or bagged tea for brewing kombucha if the tea leaves are old, they could be moldy or dusty.
Don’t use flavored teas or essential oils for flavoring because the oils will rise to the top of the liquid and damage the SCOBY by blocking the oxygen flow.
If you’re experimenting with ingredients and making second fermentation kombucha be sure you have some backup SCOBYs. When you add ingredients like dried fruit, fresh fruit, or whole spices, you’re also adding more things that molds like to colonize.