What is a SCOBY?
A SCOBY is a cellulose mat that houses the bacteria and yeast cultures that turn sweet tea into kombucha. A new or “baby” SCOBY is produced each time you make kombucha, and the SCOBY also helps turn sweet tea into more kombucha. It’s basically the means through which kombucha replicates itself.
It’s similar to how sourdough bread bakers have a “mother” dough or sourdough “starter.” That starter is a unique collection of yeasts that needs to be “fed” with flour and water and is used to make more loaves of sourdough. It’s the exact same story, except instead of flour and water, SCOBYs need to be fed with tea and sugar. And instead of producing sourdough, SCOBYs produce kombucha.
Kombucha SCOBYs go by a lot of names:
The mother culture
The kombucha culture
The mushroom (which is inaccurate; it’s not a mushroom)
But “SCOBY” is the most common term used by kombucha home brewers. It stands for Symbiotic Culture of Bacteria & Yeast.
A new “baby” SCOBY will usually grow across the top surface of your liquid with each new batch of kombucha. So it'll take the shape of whatever vessel you brew in. Oftentimes, it’ll be attached to your original “mother” SCOBY and will
look like a layer on top. But if they’re not attached, that’s perfectly fine as well. You can separate them from each other to make smaller SCOBYs to brew other gallons of kombucha or to share with others.
SCOBYs are usually cream to light tan in color and usually get brown-er over time. But healthy SCOBYs come in a variety of shapes, sizes and colors depending on the brewer, their environment and the ingredients used. For a small sample of what a normal/healthy SCOBY looks like, check out the SCOBY gallery.
What’s the purpose of a SCOBY?
Many people theorize that the SCOBY forms across the top of the brewing vessel to help create a barrier between the liquid and the air above it. By creating at least a bit of a “seal,” it’s an added layer of protection to prevent dirt/other bad bacteria or microbes from coming into contact with the brew. Oftentimes, I find that my finished, fermented kombucha has at least a little bit of carbonation (even though I only cover my brew vessels with a cloth). Even though there’s no airtight cover on my brew, small amounts of carbon dioxide can build up in the liquid just because the SCOBY created a natural “lid.”
The SCOBY is also acts as a “house” that bacteria and yeast can live in and latch on. You may see some stringy, brown yeast attached to a SCOBY. That’s perfectly fine — those yeasts are your friend.
So, do you need a SCOBY to create more kombucha?
I cover this topic in this video. When making kombucha, the SCOBY is really only part of the picture. A lot of brewers think you need a SCOBY in order to make more kombucha, but to be totally honest, you don’t really need a SCOBY as long as you have a good amount of starter tea.
As a quick refresher, kombucha is basically sweet tea that undergoes fermentation with the addition of a SCOBY and starter tea from a previous batch of kombucha. And starter tea is just another term for kombucha tea that’s undergone a successful first fermentation.
But if you don’t have a SCOBY, you can still produce a successful fermented kombucha with just the addition of a good amount of starter tea.
In most instances, the starter tea will have enough yeast and bacteria to successfully inoculate your sweet tea brew. And you’ll most likely end up growing a new baby SCOBY across the top of your vessel even if you didn’t start with a mother SCOBY.
In fact, a lot of people (I’m looking at you, Reddit) will nitpick over whether or not you should call it a “SCOBY” or a “pellicle.” Because they believe that technically the “pellicle” or cellulose mat is just byproduct of the fermentation process. Technically, the symbiotic culture/colony of bacteria and yeast (SCOBY) actually resides in the kombucha liquid itself. Because the liquid is full of bacteria and yeast too, right?
I agree that it's scientifically accurate to nitpick and say that the SCOBY is really the liquid a.k.a. starter tea, but most home brewers refer to the cellulose mat as the “SCOBY.” And they refer to the bacteria and yeast-filled kombucha liquid as “starter tea.” So I’ll stick with that vernacular and naming convention to avoid confusion here.
And for whatever it's worth, in my side-by-side experiments fermenting kombucha batches with and without a pellicle (I used 2 cups of starter tea and the same ingredients in both batches) - I actually found that the batch that I used a pellicle + 2 cups of starter tea consistently fermented faster than the batch that only contained 2 cups of starter tea (no pellicle). So while they both did ferment, the one with the pellicle seemed to acidify faster. That's why I still use the pellicle in my day-to-day brewing, whether or not it's technically necessary. I figure why not give my kombucha the best shot I've got against mold and harmful pathogens if I've got so many spare SCOBY mats/pellicles anyhow?
Can I eat the SCOBY? What can I do with it?
Since new SCOBYs form with almost every new batch you brew, home brewers often find themselves with an excess of SCOBYs after brewing a few batches of kombucha.
So what do you do with your extras? Firstly, I recommend saving some backups in case anything bad happens to your kombucha brews. You can read more about SCOBY care and building a SCOBY hotel here.
But if you already have a good amount of SCOBYs reserved:
You can eat it. It’s up in the air on whether or not it has much (if any) nutritional value. Some people think that it contains concentrated amounts of the good bacteria and yeast that resides in kombucha. Some people think that it’s just a cellulose byproduct of the fermentation process. It is edible, though — it is a bit rubbery and has the texture of slightly over-cooked squid. There are recipes for SCOBY fruit leather and SCOBY jellies out there. Or people puree them into smoothies. If in the future, I try some of these out, I’ll be sure to post about it here on this site!
Share it with others who want to brew kombucha. You can read more about how to share a SCOBY here.
Make DIY kombucha skin care and beauty products out of it. Learn how here.
Try some experimental brews with it using ingredients you wouldn't typically try.
People say you can feed it to your pets. Home brewers like to feed it to their dogs, chickens and horses -- though I've never done so myself.
Some people even make SCOBY “leather” and make wallets/purses out of it, but I haven’t tried it myself.
What about SCOBYs that form in the bottle once I’ve flavored my kombucha?
Baby SCOBYs can also form in the bottle during second fermentation. Especially with fresh fruit pieces, herbs or purees with fruit pulp, I usually find that baby SCOBYs like to latch onto and form around those more “solid” objects in my bottles.
I don’t mind them, so I just gulp them down. You may choose to strain your kombucha if there’s too much pulp/sediment or if you don’t like the texture. That’s fine as well.
You can’t really totally inhibit SCOBY growth because this is a real, raw, natural process. But you can read my posts on straining/minimizing baby SCOBYs and flavoring for some different tips on making kombucha that produces less sediment or smaller baby SCOBYs.
You can’t save or use baby SCOBYs that have already come into contact with flavorings, though (even if they’re natural fruit flavorings). Flavors can throw off and degrade/kill SCOBYs over time. So if you don’t like those flavored baby SCOBYs in the bottle, you can just toss or compost them.