Kombucha is a drink made by fermenting tea. When food or drink undergoes fermentation, it collects probiotics.
These probiotics are the source of health benefits claimed by kombucha drinkers. Fermentation in liquids also creates carbonation.
First Fermentation
The initial process to making kombucha involves combining starter tea, a SCOBY, and fresh sweet tea. This combination of ingredients is placed in a jar and covered with a tightly woven cloth.
The cloth allows oxygen to enter the liquid but keeps pests at bay. The covered jar is then placed in a dark, room-temperature spot and left to ferment for 7 to 12 days.
At the end of this period, known as the first fermentation, you’ll be graced with unflavored, non-carbonated kombucha. This liquid is just fermented sweet tea, not very akin to the kombucha we buy from our grocery stores.
You can consume your base kombucha after the five-day mark. This liquid won’t have much flavoring to it.
If you want to flavor your kombucha and allow it to carbonate, it’s time to move on to second fermentation.
Second Fermentation
To begin your next round of fermentation, remove the homemade kombucha from its dark corner. Uncover your jar, and remove your SCOBY. You’ll want to transfer two to three cups of your kombucha with your SCOBY to keep it moist and be the base of your next batch.
With the SCOBY removed, stir the liquid well. Yeast may have settled to the bottom of your jar, and we want that bacteria distributed evenly as we bottle this brew.
Pour the liquid into your bottle(s) of choice. For flavoring, it is recommended to use one-fourth to one-third cup of fruit juice or puree for every 16 ounces of kombucha.
Seal your bottles tightly. Then, place the bottles in your dark room temperature area again. Leave the bottles there for two to three days. After three days, move your bottles to the fridge.
Once the bottle has thoroughly chilled, your kombucha is ready to enjoy!
Why Does the Kombucha Need to Sit for Another Three Days?
During the fermentation process, carbon dioxide is formed. Carbon dioxide is such a huge byproduct of the fermentation process that wineries have special guidelines to protect workers from carbon dioxide inhalation.
The first fermentation doesn’t enable carbon dioxide build up. Having the jar uncovered is necessary for proper fermentation, but it allows any carbon dioxide produced to be released into the atmosphere.
Oxygen has to be available at the initial stage for aerobic bacteria to grow. Sealing the jar during the initial fermentation would halt the fermentation process.
When we transfer the initial batch of kombucha to a sealed vessel, the carbon dioxide can be contained. This makes the drink carbonated.
Adding pureed fruit or fruit juice to the bottle amplifies the carbonation. The sugars in your flavoring will feed the bacteria and yeast causing them to produce even more carbon dioxide.
If you do not wish to flavor your kombucha, you can add plain sugar instead of fruit to your batch before bottling to feed the yeast.
At room temperature for more than three days, your kombucha can begin to over-carbonate. This major excess of carbon dioxide can cause your bottle to open or shatter.
For your safety, it is not recommended to second ferment at room temperature longer than three consecutive days. If you find after chilling the post-three-day liquid that it isn’t as carbonated as you would like, then you can place the bottle back at room temperature and ferment for another day.
After the additional day, rechill the bottle and taste test it again. It’s better to take this approach one day at a time than to over-carbonate your homemade kombucha, risking injury to yourself and loss of time and supplies.
Second Fermentation Success
For the perfect batch of homemade kombucha, you’ll want your second fermentation to go smoothly.
First, it is crucial to stir your liquid before adding it to the bottles. Look over your first batch liquid once the SCOBY is removed.
If you see stringy bits floating around or a jellylike substance settled at the bottom of your jar, these are totally normal and super-important materials that you want to distribute evenly between the bottles.
These are home to the microbes that will feed on our added sugars and do the laborious task of creating carbon dioxide in our kombucha. If Bottle A gets more microbes than Bottle B, Bottle B will be significantly less carbonated at the three-day mark.
The organic material you flavor with can have a big impact on the carbonation level as well. It is recommended to use pureed fruit or fresh fruit juice to flavor your kombucha because these forms make the sugars in the fruit more bioavailable to the yeast.
If you’re utilizing chunks of fruit or pieces that have been dried, it will take significantly longer for the yeast to break down these fruits to obtain their sugars.
In that time, carbon dioxide bubbles can pop. The microorganisms in your kombucha may also grow out of control if left at room temperature for that long.
When considering essential oils or extracts, you have to be very careful when adding these to your kombucha. Some essential oils are antibacterial. They could kill off the bacteria in your kombucha. Without the beneficial bacteria present, you just have spoiled sweet tea.
Extracts could also pose a danger to the life within your kombucha. Extracts are made with alcohol. While most of the alcohol burns off during the cooking or baking process, in kombucha flavoring, the alcohol content would kill your bacteria colony.
The vessel you choose for the second fermentation is also of great importance.
As carbon dioxide builds up in your liquid, the total mass filling the bottle will increase. Under pressure, thin glass bottles have a tendency to shatter.
You want to choose a bottle that can withstand this pressure such as flip top bottles that come with their very own sealing cap, or you can recycle store bought kombucha bottles.
The cap of your bottle should be sturdy and able to create an airtight seal. If using twist top lids, tighten the lid as much as you possibly can to prevent any air from escaping.
Wide vessels such as mason jars are not recommended at this stage. The seals on canning jars are not made to be repurposed.
It is incredibly difficult to get a perfect seal with a reused mason jar, and that usually involves heating the seal. This excess heat could harm the bacteria in your kombucha.
Your bottles and their cap should be thoroughly cleaned before use. You do not want any mold or harmful bacteria to enter your kombucha at this crucial stage. Be sure to completely clean and dry both parts before use as well.
While much of the science happens in the initial fermentation, the magic takes place in the second fermentation. During this two- to three-day period, your kombucha goes from tangy sweet tea to a flavorful and effervescent liquid chock full of probiotics.
Carbonation is most pronounced at room temperature. Chill your secondly-fermented kombucha before tasting it to avoid it bubbling out of the container and creating a mess.
I have a bachelor’s degree in Computer Information Systems and over 10 years of experience working in IT. As a homeowner, I love working on projects around the house, and as a father, I love investigating various ways to keep my family safe (whether or not this involves tech). I’ve also played guitar for almost 20 years and love writing music, although it’s hard to find the time these days.