SCOBY is an acronym for Symbiotic Culture of Bacteria and Yeast. The SCOBYs in kombucha are in a gelatinous form that tends to float on the liquid. SCOBYs produce a unique fermentation process because they contain lactic acid bacteria, acetic acid bacteria, and yeast.
When this combination of bacteria and yeast combines, cellulose is formed. Cellulose collects and forms the gelatinous body of the SCOBY.
SCOBY in Kombucha Production
When making kombucha, you can’t skip out on the SCOBY. When morphing sweet tea into kombucha, the SCOBY provides the necessary bacteria for the fermentation process. Without the bacteria to feed on the sugar in the tea, spoilage will happen instead of fermentation.
The SCOBY disc in your kombucha also serves as a protective barrier against outside bacteria and pests.
With your SCOBY capping off your kombucha, some of the natural carbonation is preserved during fermentation. Carbon dioxide is released by bacteria feasting on the sugars in the base tea.
Carbon dioxide forms tiny bubbles in your drink, and the SCOBY keeps those bubbles in.
Growing Your Own SCOBY
You can purchase SCOBYs in starter liquid online or borrow some from a fellow kombucha brewer. When those options aren’t available, you may look into growing your own SCOBY.
The easiest way to grow a SCOBY is with previously made kombucha. Whether it’s store bought or homegrown, allow your kombucha to ferment at room temperature until a thin blob forms at the top of the liquid.
That blob is your new SCOBY!
When Kombucha Isn’t Available
When you can’t get your hands on unpasteurized kombucha, or you simply want to do every step from scratch, there are ways to grow a SCOBY without kombucha.
Make a gallon of sweet tea and allow it to come to room temperature. Then add commercial yeast and yeast nutrients to your tea. Once the yeast has settled, you’ll need to add lactic acid cultures to the mixture. Lactic acid cultures can be found in DIY kefir and yogurt kits.
Once your ingredients are well incorporated, pour the inoculated tea into a jar and cover the top with a tightly woven cloth. You should secure the cloth around the mouth of the jar with a rubber band to keep pests out.
If you are unable to obtain yeast, you can attempt to attract wild yeast into your sweet tea. Place your tea in a wide mouth jar. Cover the top of the jar with a cloth.
Place your lightly covered jar in a windowsill or outside in the open air. Allow the tea to remain there for approximately two weeks.
After some time, bring the jar inside and seal with its respective lid. Allow the yeast to bloom. While blooming, small bubbles and clumps will begin to form.
Bacteria will grow in the mixture after some time. It could take several months for a SCOBY to take shape with this method.
Another option to create your own SCOBY is to ferment fruit. Begin by chopping up any fruit that is not of the citrus variety. Coat the fruit in copious amounts of sugar.
Stir the fruit until it is evenly coated with sugar and begins to break down. Place the fruit and sugar into a jar filled with non-chlorinated water. Chlorine will kill any bacteria you wish to grow.
Add half of a cup of vinegar to the macerated fruit. Stir the mixture generously before covering the jar with a tightly woven cloth.
Move the jar to a cabinet or similar dark space that is room temperature. Allow the sour fruit concoction to ferment for three to four weeks, stirring it once a week.
You can achieve a similar process by vacuum packing your non-citrus fruit and placing it in a warm spot. Soon, the bag will begin to bloat as gases are released by the decaying fruit. After three weeks, open the bag, and dump its contents into a jar.
Combine these contents with non-chlorinated water and allow to ferment in the dark at room temperature for one week.
SCOBYs are not desired for their beauty. Their function is required in the process of making kombucha. How do you tell if your SCOBY is just ugly or has gone off?
Mold can form on your SCOBY if the spores get into your kombucha. Mold needs oxygen to thrive, so it will only be present on the top layer of your SCOBY.
Mold has a fuzzy, textured appearance and can be seen in shades of white, black, green, and blue.
If the spots you’re seeing are brown or beige in color and appear to have a wet film over them, don’t fret. This is just bacteria forming, not mold.
When a SCOBY turns black, it’s time to retire it. SCOBYs are living organisms and have their own expiration dates.
Clumps of brown string-like material growing on the bottom of your SCOBY is totally normal. These are just yeast clumps.
They may detach from the SCOBY mother and float around in the liquid before settling to the bottom of the jar. They can remain at the bottom of the jar and should be left alone until your kombucha has finished fermenting.
A clear SCOBY is a sign of a healthy juvenile. When a SCOBY first begins to form, the cellulose it is composed of can be transparent. As the colony grows, the SCOBY will become more opaque and take on a natural beige coloring.
SCOBYs can grow to be one-fourth to one-half of an inch thick. If your SCOBY is thinner than one-fourth of an inch, leave it alone and allow it to grow.
The SCOBY should always remain at room temperature. Any temperature above or below room temperature could kill your SCOBY.
Heat will irreparably kill the bacteria in your SCOBY, and extreme cold will halt the bacteria’s life cycle. You may be able to fix a SCOBY exposed to cold, but it is unlikely you will be able to revive the bacteria after extended exposure to cold.
Your sense of smell can also be used to indicate a SCOBYs health. While fermented beverages and foods may not smell like roses, their tangy smell is unmistakable.
If your SCOBY is producing an odor that is putrid or smells rotten, an unhealthy amount of bad bacteria is present. Discard the SCOBY as well as the liquid it was in.
The texture of a SCOBY should be slimy. That may not seem like a pleasant thing to handle, but if your SCOBY is not slimy and appears dry around the edges, it is dying.
This could be the result of liquid deprivation or the SCOBY may have run its natural course.
SCOBYs are incredible natural hotels for bacteria and yeast. They lend themselves to the fermentation process and create wonderful products for us to consume.
From beginning to end, the life cycle of a SCOBY is in your hands. You may purchase an already established SCOBY, or you can choose to construct your own through the various methods discussed.
Whatever you choose, take care of your SCOBY. In turn, it will take care of you.
Sarah is the founder of Baking Kneads, LLC, a blog sharing guides, tips, and recipes for those learning how to bake. Growing up as the daughter of a baker, she spent much of her childhood learning the basics in a local bakery.