Touted with health benefits, kombucha is a fermented carbonated beverage made from tea. It’s a delicious alternative to unhealthy sodas, and is easy to make from scratch in a wide variety of flavors.
Kombucha is one of the few things that I have been making pretty consistently for many years. While I love fermenting foods and often make everything from milk kefir to fermented ketchup, I also often get tired of having to keep multiple ferments alive. More than once, I’ve allowed my ferments to fend for themselves, and they eventually end up dying off. (That includes my sourdough starter, my milk kefir grains, and my water kefir grains.)
Kombucha is different, though. Both my husband and I really love it. Plus, kombucha SCOBYs are a bit more resistant than most of the other ferments. So, if we do stop making it for a while for some reason, the SCOBY usually survives even prolonged breaks, and we can start making kombucha again when ready.
So what, exactly, is kombucha?
Kombucha is a carbonated probiotic beverage made from fermenting tea. It is said to have many health benefits, but also just happens to be very tasty. If you want to remove unhealthy sodas from your diet and are looking for a healthier replacement, then kombucha might be perfect for you.
While you could buy kombucha from the store, it’s generally very expensive to buy. By making it yourself, you can not only save money, but control the ingredients and the entire process. Plus, you can experiment with a wide variety of flavors!
Is Kombucha healthy?
Interestingly enough, despite containing candida species, it has also been shown to have anti-microbial properties against pathogenic candida species (as well as other pathogenic bacteria and yeasts). Whether or not drinking kombucha would be beneficial to those with candida problems probably depends on the person and the species that affects him or her.
Apart from that, kombucha may retain some of the antioxidant properties of the tea. Some think that it may even help you lose weight in the same way vinegar and green tea may. (This could also be due to the fact that gut bacteria populations seem to be different in obese vs. non-obese people.)
Kombucha has other health benefits too. It may prevent and even help treat diabetes and improve liver and kidney function. For those worried about their cholesterol, kombucha has been shown to have curative effects on hypercholesterolemia.
Even more unbelievable is that it has inhibitory effects on cancer cell growth. That means that it may even help prevent cancer.
Is it “paleo”?
If kombucha is “paleo” depends on how strict you are with your definition of “paleo.” If you are trying to eat like a caveman, then you’ll probably say “no” because cavemen probably weren’t drinking kombucha. If, on the other hand, you are just trying to eat a healthier, less processed diet, then you will probably accept kombucha as “paleo-friendly”.
Despite the fact that kombucha is usually made with cane sugar, most of the sugar is probably used up in the fermentation process. That said, even if you drink kombucha on the more fermented (sour) side, some sugar will likely remain. So, despite the possible health benefits, one could again reasonably argue that kombucha isn’t “paleo” just on that basis alone.
Jun vs. kombucha
For those who are looking for a similar beverage that does not use cane sugar, jun may be of interest to you.
Jun is a fermented beverage that is similar to kombucha but instead made with honey and green tea. I’ve made jun in the past, but have to admit that we like the flavor of kombucha much better. Other people probably might prefer the flavor of jun. So, it may be worth trying, especially if you are following a GAPS protocol or are more strictly paleo.
I had planned to write a post about how to make jun, but have to admit that we didn’t stick with it long enough. My jun SCOBYs, which are different from kombucha SCOBYs, eventually died off before I could get around to it.
Kombucha uses only a few simple ingredients that you may already have at home (not including the SCOBY). Because it is a fermented tea, you’ll need water, tea, and some sugar to feed the bacteria and yeasts.
You’ll also need to acquire a kombucha SCOBY. That, for most people, is probably the most difficult part of making kombucha.
What is a SCOBY?
A SCOBY is a Symbiotic Colony Of Bacteria and Yeasts. It’s white, slightly rubbery, and looks a lot like the “mother” that forms atop homemade apple cider vinegar (or other vinegars like my ginger vinegar). This “cellulose pellicle” looks similar because both kombucha and vinegar include acetobacter, a type of acetic acid bacteria.
These bacteria and yeasts work to transform sweetened tea into a healthy, carbonated beverage. Together, they are strong enough to inhibit the growth of other, potentially dangerous, bacteria and yeasts.
Where can you find a SCOBY?
Once you make kombucha, a new SCOBY should form on the surface. So, with time, you’ll likely end up with numerous SCOBYs that you can share with others. If you’re lucky, you will be able to find someone who can share a kombucha SCOBY with you.
If not, you’ll probably have to do a search online for someone who is either selling grains or giving them away. I’ve seen them offered on Amazon, on eBay, and also in local listings in phone apps like Wallapop.
How to make a kombucha SCOBY
Some people have asked me if it is possible to make your own SCOBY. While I had read that it was possible to start your own from store-bought kombucha, I hadn’t yet tried it myself. Seeing how I love to experiment, though, I’ve finally grown my own SCOBY from store-bought kombucha.
At first, I tried just leaving just over half of the bottle open and covered with a cloth, just as if I were brewing kombucha. While something was forming on top of the surface after several weeks, it wasn’t getting thick. (The weather was on the cooler side which could also have been affecting the speed of growth.)
I decided to mix a small amount of sweetened tea with the store bought kombucha and cover it as if I were brewing kombucha with a SCOBY. After a couple of weeks I could definitely see a thin layer of SCOBY forming on the surface. The tea also soured and tasted like kombucha.
Rather than leave it alone to continue to form a thicker SCOBY, I decided to add more sweetened tea to the mixture, without removing any of the kombucha or the SCOBY film. After a couple more weeks, you can see that the kombucha formed a much thicker SCOBY. If I were to continue fermenting it, I am sure that I would develop a SCOBY large enough to make larger batches of kombucha.
In order to make your own SCOBY from store-bought kombucha, choose a brand that says it is not pasteurized. Pasteurizing can kill off some of the organisms that we want included in our symbiotic culture of bacteria and yeasts.
What type of tea?
While kombucha is generally made with black tea, most types of tea (of the tea plant Camellia sinensis) should work to make kombucha. Black tea has a higher concentration of purines than the other varieties. Purines help the microorganisms in the SCOBY more actively ferment the sweetened tea. That’s why adding some black tea to your mixture can help ensure a well-fermented kombucha.
I’ve made kombucha with black tea, green tea, and white tea. After taste-testing numerous batches, I’ve decided that I like making kombucha with a mix of both black and green teas. (If I’m out of black tea, I have used white tea instead. It, like green tea, makes a milder kombucha.) You can use one or the other, or both like I do.
It’s also a good idea to choose organic tea for kombucha to avoid the possible pesticides, herbicides, fungicides, or chemical fertilizers that may be used to grow regular tea.
Avoid flavored teas, especially those that use oils to flavor them. The oils can affect the fermentation and growth of the SCOBY. Earl Gray is a common tea to avoid because it is flavored with bergamot oil.
Ideally, you should use filtered or spring water for making kombucha. Because of it’s delicate balance of bacteria and yeasts, chemicals like chlorine in tap water may damage some of the species of the SCOBY culture. Filtering the water or using spring water helps prevent that problem.
Sugar is a necessary ingredient in the making of kombucha because it feeds the microorganisms in the SCOBY. Without sugar, the yeasts can’t make an alcohol that gets converted into an acid by the bacteria. White sugar is the easiest type for the yeasts to ferment. That doesn’t mean that you can’t try using other sweeteners like unrefined cane sugars or maple syrup, but I’d suggest waiting until you have excess SCOBYs before you start experimenting with other sweeteners as they can affect the fermentation process.
Don’t use raw honey as it may interfere with the delicate balance of microorganisms in the SCOBY. (If you want to use honey, try looking for a jun SCOBY to use.
If you want to add a honey flavor to the kombucha, consider adding a tiny bit of honey during the second fermentation. During the second fermentation, it can no longer damage the SCOBY or disrupt the main fermentation process.
Over the years, I have normally used large glass vessels (glass gallon jars) for fermenting the kombucha. You should generally avoid contact with metals (although occasional contact with stainless steel shouldn’t be a problem.)
Because kombucha is acidic, toxic substances from whatever container you use could leach into the kombucha. That’s why it’s important to use food safe containers. (Most people avoid using plastics, too, for that reason.)
I prefer glass or ceramic. Keep in mind that some ceramics (generally older ones) may be contaminated with lead, cadmium, or other heavy metals. Even older glass jars may have a similar problem.
I’ve been using a large ceramic crock meant for fermenting foods. I’m not sure if it’s the size of the container or the opacity of it, but I’m convinced that the kombucha made in the fermenting crock tastes better than the batch I make in the large glass jar.
Apart from the fermenting jar or crock, you’ll also need a cotton cloth or coffee filter to cover the mouth of the jar and keep dust and insects out. This should be secured in place with a rubber band or something similar.
For the second fermentation and storing the finished kombucha, choose bottles with an airtight lid. (I like glass bottles with flip top lids.) Bottles with a wider mouth allow you to add fruits and other ingredients for flavoring the kombucha more easily. (Kombucha in bottles with a wider mouth is also less likely to explode out of the bottle upon opening it too quickly.)
Kombucha is very easy to make, but takes a little bit of time and patience. Luckily, it’s mostly “hands-off” time where you allow the SCOBY to do its thing. You don’t have to spend a long time slaving over a hot stove. If you can make tea, you can make kombucha!
To begin, bring the water to a boil. This will help kill off any possible microbes in the water. Once boiling, remove the water from the heat source. Add in the sugar and stir it into the water until it has dissolved. Immediately add the tea leaves to the hot water. (You can use teabags or loose tea with a strainer. I used to use my homemade teabags, but now use stainless steel strainers like these.)
Steep the tea for around 10 minutes. You can remove the green tea before the black tea if you find it to be bitter when steeped too long. I used to worry about it, but have since found that I can’t tell a difference in the finished kombucha either way. After the tea has steeped to your liking, remove the tea bags and let the sweetened tea cool to room temperature.
Once cool, add the sweetened tea to a large glass container. Top it off with some starter kombucha. If you don’t have any starter kombucha or kombucha from your last batch, you can use spirit vinegar or apple cider vinegar to help lower the pH and help prevent mold from forming on the SCOBY. That said, using only kombucha is always the ideal choice.
Spirit vinegar or pasteurized vinegar may be a safer choice for helping start the first batch of kombucha (vs. raw vinegar with a mother). That’s because spirit vinegar won’t have any living organisms that can alter the balance of microorganisms in the SCOBY. Raw vinegar like apple cider vinegar has its own balance of microorganisms that may be added to the kombucha and SCOBY, possibly affecting the flavor of future kombucha brews.
Cover the glass container with a cloth that will let the mixture breathe while keeping out dust and insects. I use a square of cotton cut from some old cotton sheets and secure it in place with a rubber band. You can also use a coffee filter instead.
Store the mixture undisturbed for at least a week before tasting it.
Effects of temperature
Ideal temperatures for kombucha brewing are somewhere between 70º-80ºF(21º-27ºC). That doesn’t mean that you can’t brew kombucha if you have temperatures higher or lower than that. Outside of that temperature range, though, you are more likely to run into problems.
When it is colder than 70ºF, the brewing process will take longer. With a slower fermentation, you are more likely to develop mold. If possible, when brewing at low temperatures, add more starter kombucha to lower the pH and help jump start the fermentation better.
Above 80ºF, you are more likely to throw off the balance of your kombucha. The Kombucha SCOBY is a symbiotic colony of bacteria and yeasts. If the temperature is too high, you could throw off the balance in the favor of too many yeasts in the mixture.
Your kombucha is ready when it has reached the desired level of fermentation. As the days go by, the tea mixture will no longer taste like sweet tea, but instead will become sour. Most people prefer kombucha after around 7-10 days of fermentation. If you are brewing in cooler temperatures, you’ll probably want to ferment it longer than that. If it’s hot out, you’ll probably want to stop after a week or so.
The first time you are ferment kombucha, you’ll probably want to leave it a bit longer, too, especially if you don’t have a lot of starter kombucha to really get the ferment going quickly.
When tasting the kombucha, try not to disturb the newly forming SCOBY on top of your liquid. You can slide in a straw along the edge of the jar into the kombucha and pull some liquid out to taste it. (You can also use jars with a spigot for removing the liquid from the bottom of the jar without disturbing the SCOBY.
Bottling the kombucha
Once you’ve made a Kombucha to your liking, take out the SCOBY(s).
When you brew kombucha, a new SCOBY normally will form on the surface. It may be separate from your first SCOBY or may fuse with it, forming new layers, if the original SCOBY was floating.
Pour the kombucha into bottles. I like to use glass bottles with flip cap type stoppers. Make sure to use high quality bottles so that they don’t break from the buildup of gas inside them.
Remember to save at least a cup of your kombucha to use as a starter for your next batch!
Once bottled, you can drink the kombucha, as is, immediately or do a second fermentation to build up more gas and flavor the kombucha.
The second fermentation
To do a second fermentation, leave the bottles tightly capped at room temperature. The kombucha will continue to ferment and will build up gas in the tightly sealed bottle.
After a few days, you’ll probably notice that your kombucha is now much more carbonated.
To achieve a more carbonated kombucha (and add flavor), add some fruit to the kombucha during the second fermentation. Fruits add more sugar to the brew, which results in a more active fermentation. (Be careful when using fruits with a lot of sugar (like watermelon) as they can cause the gas to build up very quickly!)
Once you’ve reached the desired carbonation level, strain out the fruit and store the bottles of kombucha in the fridge.
It’s a good idea to occasionally “burp” the bottles of kombucha. This is done by opening them every couple of days to let out any excess gas. (Do this daily while at room temperature during the second fermentation.) While it’s best to use glass bottles to avoid toxins from seeping into your kombucha, glass is also more susceptible to breaking. This is merely done to prevent the bottles from exploding if the kombucha continues to ferment without allowing the extra carbonation to escape.
Serve chilled and enjoy! (You can strain out the yeast strings that may form if you prefer, or just leave them in and drink them.)
The best kombucha flavors
While unflavored kombucha is delicious, it’s simple and fun to add flavor to your homemade kombucha.
Flavoring, as hinted above, is done during the second fermentation. The ingredients used to flavor kombucha could potentially damage the SCOBY. That’s why the second fermentation is the best time to add flavors. (Plus, fermenting with fruits in closed bottles allows for carbonation.)
Rather than just leaving the kombucha to ferment alone in tightly capped bottles, you can add fruits and other ingredients to the bottled kombucha. After a day or two of fermenting with the other ingredients, strain them out and store the kombucha in the refrigerator.
While a variety of fruits can be used to flavor kombucha, some give much better results that others. Fruits with a high sugar content need to be carefully watched as the kombucha can build up a lot of gas in a closed container if too much sugar is present. My favorite fruits for flavoring kombucha are berries. (Raspberries are my very favorite!) I also really like pineapple (but wasn’t a fan of watermelon kombucha).
While you can use fresh fruit, I find it more convenient to use frozen or dried fruits. (It’s also easier for me to find dried organic raspberries vs. the fresh ones. Lately, I use dried fruit powders because they tend to be cheaper for the same quality.
Lemon and lavender
Citrus fruits combine really well with herbs. One of my favorite combinations is lemon and lavender. Rinse an organic lemon well and slice it into wedges. Add a wedge or two of lemon with some clean lavender flowers to the kombucha.
Because lemon and lavender don’t really add much sugar to the second fermentation, you can add a few raisins to the bottle to help increase the sugar content slightly.
Pineapple also combines well with a variety of herbs. It may sound strange, but I love combining it with sage leaves.
Lychee and honey
One year, we were lucky enough to get some fresh lychees from our tree. They are delicious in kombucha either alone or combined with a touch of honey, for flavor.
Rose petals and dates (or honey)
You may know by now that I love the flavor of rose petals. (I use rose water to make Turkish delight, rose petal gummy treats, and to flavor panna cotta.) Rose petals aren’t just for desserts, though. They’re absolutely delicious in kombucha!
Because rose petals don’t have sugar, it’s best to combine them with dates or a touch of honey. You can use fresh petals, dried rose petal tea, and/or rose water.
Ginger and lime
Add a clean piece of ginger root and a wedge of lime to the kombucha for a delicious exotic flavor. Again, in this case, you may want to add some raisins or a date to add some sugar to the mix.
Spirulina and/or chlorella
I thought adding spirulina and/or chlorella was a genuis idea. I was drinking spirulina in water often anyway, and thought why not add it to kombucha.
Unlike the fruit powders, the algaes don’t really color the kombucha. To drink a green kombucha with spirulina or chlorella, you have to leave the powder in the kombucha and shake it before serving. (These powders, unlike the others, sink to the bottom of the bottle.)
While it’s fun to experiment, these were a flop for me. (I only tried these once!)
What are your favorite combinations? I’d love to hear from those of you who have experimented to see what flavors are your favorites!
While brewing kombucha is generally easy, some issues may come up occasionally.
Kombucha is too sour
The level of sourness is generally determined by how long the kombucha has been fermenting. If your kombucha is too sour, you’ve probably fermented it too long. This happens more frequently in the summer, when it’s hot out. The kombucha will ferment much more quickly in the heat.
With the next batch, ferment the tea less time.
Stringy stuff hanging from the SCOBY
While it may look alarming, the stringy stuff hanging from the SCOBY, or floating in the kombucha, is perfectly normal. It’s just yeast. You can either strain it out, or drink it with the kombucha.
SCOBY not forming
If a SCOBY isn’t forming (or your old SCOBY isn’t getting thicker) when you ferment a new batch of kombucha, it’s a sign that something isn’t right. If it’s your first time fermenting kombucha, it could just be that your SCOBY was somewhat dormant and needs a cycle or two of making kombucha to get going again.
On the other hand, it could be a sign that something else is wrong.
First, take a closer look at the ingredients that you are using. Check to make sure that your tea isn’t flavored, and try a different type of tea if you think the tea may be causing problems. Stick with white sugar (at least for a while) if you find that a SCOBY isn’t developing when using other sweeteners. Make sure your water isn’t chlorinated or somehow contaminated with chemicals.
Next, take a look at the environment. As I mentioned earlier, if the temperature isn’t ideal, it can cause problems during fermentation. Even more important than the room temperature, though, is the temperature of the tea. If you add the SCOBY to the sweetened tea before it has fully cooled to room temperature, the heat can damage the delicate culture.
Another problem is chemical damage. It’s best to clean the brewing containers with alcohol or vinegar rather than using soap or other cleansers. Residual soap can also damage the SCOBY.
While not common, mold can sometimes form while brewing kombucha. This is more likely to happen when trying to brew kombucha in a cool environment. This can also happen if you didn’t use enough starter kombucha or for some other reason.
I’ve only had this happen a couple of times over the years (always during the cold of winter). One time I had left the vegetable scraps, meant for our compost heap, right next to the kombucha vessel. I forgot about it for a couple of days and they developed some mold. Since it was right against the kombucha jar, some of the mold came in contact with the cloth that covered my kombucha. I assumed that the mold from the vegetable scraps had contaminated my kombucha blend.
So, yes, be careful of what you have around your kombucha! Even without direct contact, the microbes in the air can change your kombucha or SCOBY.
Mold will likely be obvious, but some people mistake the SCOBY forming for mold. Some SCOBYs form differently than others. Mold will look fuzzy or hairy, and often be a color other than white.
Once you see mold in your kombucha, it’s best to throw out the entire batch (as well as the SCOBY).
I tried to reuse a SCOBY from a moldy batch once to see what would happen. It was at the bottom of the kombucha jar and the mold floating on the top of the kombucha. I thought it wouldn’t have been contaminated, but cleaned it with vinegar, just in case. Even after peeling off the outer layers and rinsing the SCOBY in vinegar, when I made the next batch of kombucha with it, the liquid started to smell moldy and eventually also developed mold.
To be on the safe side, begin from scratch any time that you see mold forming in your kombucha brew. Use a new SCOBY too! (That’s why it’s a good idea to set aside extra SCOBYs for friends or emergency use.)
Kombucha makes you feel sick
If you find that kombucha is making you feel worse rather than better, it may be a sign of your body detoxifying or just getting used to drinking it. You could first try by starting with very small doses, like a small shot of kombucha for a few days to see how your body reacts.
If you don’t see any improvements, though, it’s probably best to stop and/or consult with a trusted health professional. (It’s probably best to go with your instincts and not stick with it if you really feel like it is hurting you more than it is helping you.) While lots of people love how kombucha makes them feel, nothing is going to be perfect for everybody!
Storing excess SCOBYs
Once you start fermenting kombucha, you should end up with excess SCOBYs. Too many SCOBYs in your fermenting jar could make your kombucha very sour very quickly (and leaves less room for brewing kombucha).
Plus, it’s always a good idea to have some SCOBYs separate from your main batch in case a friend wants one or for starting a new batch. (If your batch goes moldy, you’ll want to toss the SCOBY and start with a new one.)
Excess SCOBYs are easy to store and keep for a very long time without needing much care. Most people call the jar of excess SCOBYs the “SCOBY hotel”.
To make a SCOBY hotel, store excess SCOBYs in a glass jar covered in sweet tea or already brewed kombucha. Then, cover the jar with a cloth and rubber band, just as you do when fermenting kombucha. The liquid inside the SCOBY hotel will get very acidic with time.
While you can mostly ignore your SCOBY hotel, with time, the liquid will start to evaporate. You don’t want to allow the SCOBYs to dry out, so occasionally check on them and cover them with more tea or kombucha if needed.
SCOBYs in a SCOBY hotel generally keep well for months on end without issues. If they start to dry out or get excessively dark in color, toss the affected SCOBYs and add new ones.
How to make Kombucha
Glass bottles with flip-top lid
Glass bottles with wide mouth and flip-top lid for adding fruits.
- 1 kombucha scoby
- 1 cup sugar
- 8 tea bags of black or green tea (or both) (around 2 tablespoons)
- 1 gallon unchlorinated water filtered or spring water
- 1 cup starter kombucha or spirit vinegar if none is available (another vinegar can be used, if absolutely necessary)
Make the sweet tea
- Bring the water to a boil, and remove it from the heat source. Add the sugar, stirring until it is all dissolved. Immediately afterward, add the tea.
- Seep the tea for around 10 minutes.
- Remove the tea bags and allow the sweetened tea fully cool to room temperature.
Fermenting the kombucha
- Add the cool, sweetened tea to a large glass or food-safe ceramic container. Top it off with some starter kombucha from a previous batch. If you don't have any starter kombucha or kombucha from your last batch, you can also use spirit vinegar to help lower the pH and help prevent mold from forming on the SCOBY. (Other vinegars may contribute new microorganisms to the SCOBY and kombucha.)
- Cover the glass container with a clean cotton cloth or coffee filter. This allows the mixture to breathe while keeping out dust and insects. Secure the cloth over the mouth of the jar with a rubber band.
- Store the mixture at room temperature undisturbed for a week. After a week, you can begin tasting the kombucha for doneness.
- Your kombucha is ready when it has reached the desired level of sourness. As it ferments, the kombucha will become increasingly sour. Most people prefer kombucha after around 7-10 days of fermentation. In cooler temperatures, you may want to ferment longer than that. If it's hot out, you may want to stop earlier.
- When tasting the kombucha, try not to disturb the newly forming SCOBY on the surface. You can slide in a straw along the edge of the jar into the kombucha and pull some liquid out to taste it.
- Once you've made a Kombucha to your liking, remove the SCOBY(s). (You should have a newly formed SCOBY on top, but it may fuse to the original SCOBY, forming new layers instead.)
Bottling the kombucha
- Pour the kombucha into bottles. I like glass bottles with flip cap type stoppers. You can drink it immediately and store in the fridge if you like. (Remember to save at least a cup of your kombucha to use as a starter for your next batch!)
The second fermentation
- A second fermentation adds carbonation to the kombucha and can also be used to flavor it. To do a second fermentation, leave the kombucha at room temperature in bottles with airtight lids.
- After a day or two (temperature dependent), you'll probably notice that the kombucha is now much more carbonated. To add even more carbonation (and flavor), add some fruit to the kombucha during the second fermentation.
- Once you've reached the desired carbonation level, strain out the fruit and store in clean, airtight bottles to keep the carbonation. Store them in the fridge to slow the fermentation process.
- Serve chilled and enjoy! (You can strain out the yeast strings that may form if you prefer, or just leave them in and drink them.)
- You should use glass or ceramic jars for brewing kombucha. I use glass gallon jars, adding less than a gallon of water (tea) to allow space for the SCOBY and kombucha starter. Ceramic fermenting crocks also work well for fermenting kombucha. You can easily adjust the ratios to fit whatever container you plan on using.
- While you can use either black tea or green tea, I actually like to use a 50/50 mixture for my kombucha. Some people are more successful with one type of tea or the other. I find either works well for me, but just prefer the flavor when using a combination. Black tea makes a more active fermentation and green tea has a milder flavor. Choose accordingly.
- Ideal temperatures for kombucha brewing are somewhere between 70º-80ºF. Outside of that temperature range, you are more likely to run into problems. When it is colder than 70ºF, the brewing process will take longer, and it is more likely that you will develop mold. You can add in more starter liquid to help compensate. Above 80ºF, you are more likely to throw off the balance of your kombucha in favor of yeasts.
It’s a good idea to occasionally “burp” the bottles of kombucha during the second fermentation and when storing it. This is done by opening the lid to allow the escape of excess gas. (This should be done daily during the second fermentation, and every few days/weeks when stored in the fridge, depending on its level of carbonation.)
It’s best to use glass bottles to avoid toxins from seeping into your kombucha, but glass is also more susceptible to breaking, so this is merely done to prevent them from exploding, which could happen if the kombucha continues to ferment without letting out the extra carbonation.
This post was originally published on June 5, 2016. It was completely rewritten, adding new information, photos, and video in May of 2021.