How To Carbonate Kombucha

While kombucha can be served fizzy or flat, many people prefer to drink it with some carbonation. This quick guide will teach you how to carbonate kombucha and troubleshoot any reasons why you aren’t getting the results you desire!

To add more bubbles, home brewers generally use a second fermentation (F2) in a sealed, airtight container.

This article assumes that you already know how to do a second fermentation but that you are not getting the fizzy results you desire!

When kombucha is put into a sealed container such as an airtight bottle, the yeasts will continue to eat the sugars added and convert them into carbon dioxide. The only difference now is that the CO2 released will be trapped in the bottle and forced into the liquid, giving kombucha its signature effervescence (an oh-so-fancy word for fizz!)

How much carbonation do you want?

While this all comes down to personal preference, we personally find that bubbles complement the flavors we add in F2.

Our goal is for there to be a pleasant amount of carbonation present when you open the bottle and serve it directly out of the fridge.

When you open the bottle, there should be a hissing noise of gas escaping. It may foam up a little, but not enough to spill out the top and waste your precious booch!

If you want to increase your carbonation, try following some of these tips!

Tips for Better Carbonation

Use high quality, airtight bottles.

The types of bottles and caps you use are super important.

We like to opt for glass bottles whenever possible. Make sure they are fermentation grade. The Bolsch style swing-top bottles that beer homebrewers use are perfect. You can also reuse store-bought kombucha bottles. They already did the hard work sourcing quality bottles for you! 

Avoid reusing beer bottles, as they may explode due to the pressure. They are made of thinner glass and aren’t the safest option. Quality and an airtight seal are important! 

Make sure to dry off the mouths of your bottles and the caps/flip-tops before closing. If you have screw-on caps, seal them as tight as possible because the pressure that builds up can loosen caps that aren’t on very tightly. We find that rubber grippers can help.

Stir the liquid in your brew vessel before F2.

After removing the SCOBY and some starter liquid for the next batch from your F1 vessel, stir the liquid around.

Yeast tends to settle on the bottom, and if you don’t stir your kombucha before bottling, your bottles will all have different carbonation levels.

Bottles that receive liquid without a lot of yeast won’t carbonate, and bottles that get too much may spray kombucha everywhere upon opening. Once everything is evenly mixed, then you can pour your kombucha into the bottles.

Use sugars that are easy for the yeasts to eat.

During F2, the yeasts are “reactivated” with more sugar.

The type of flavoring or sugar product you add is important here.

The yeasts will have a harder time breaking down whole pieces of fruit than a blended puree of fruit, fruit juice, or simple syrup. If using fruits as your primary sugar source, use fruits high in sugar content, like pineapple.

If you are brewing a more floral, savory, or aromatic kombucha and aren’t using foods with a high amount of sugar, try adding some cane sugar into the bottle before pouring your kombucha in.

For those that like the taste of “unflavored” kombucha straight from F1 but want a little carbonation, this is a great strategy.

If you have kombucha that is too carbonated, try using whole pieces of fruit instead of puree… or using less fruit puree per bottle.

Store your bottles at room temperature first.

We refrigerate kombucha to drastically slow down the fermentation process, as the yeasts become inactive at these low temperatures.

Before putting your bottles in the fridge, let them sit at room temperature for 2-4 days.

When using fruit with higher sugar content (like pineapple), we find 2 days to be ideal. For “unflavored” kombucha, 4-6 days in F2 works great for us.

Just don’t forget to add a little bit of cane sugar to help the yeasts out!

Don’t burp your bottles.

Burping is a practice that some home brewers use to make sure their bottles don’t carbonate too much and explode.

However, we find this unnecessary if you use proper bottles and caps and follow the rest of these tips.

When burping bottles, you quickly open the bottle to release some gas then close it again. This is releasing the exact gas that you wanted to build up in the first place! 

Don’t filter out the yeast.

Those somewhat gross-looking brown globs are your friends!

You will learn to love them over time if you don’t already. These guys are yeasts, and you need them to break down the sugars and build carbonation.

If you prefer a cleaner looking drink and like to filter your kombucha before bottling it, we recommend filtering your beverage as you pour it out to drink instead.

If you have been filtering before F2 and not building the carbonation you desire, try filtering less or not at all before bottling.

Leave the right amount of headspace.

Fill your bottles up close to the top, so that pressure can build in the bottle and force the CO2 into the liquid.

We recommend leaving a little bit of space at the top to give yourself a buffer when opening the bottles and releasing carbonation.

Less than an inch should do the trick. Don’t leave too much space, or the C02 won’t be forced into the liquid as easily.

We did a test filling up a bottle half the way with pineapple and ginger for F2. Even after 5 days sitting at room temperature, the carbonation level was much flatter than we would have liked. Make sure to fill those bottles up!

Keep an eye on the temperature.

Just like for F1, F2 also requires a temperature in the range between 68-86ºF (20-30ºC), ideally within 75-84ºF (24-28ºC). If your booch is coming out too flat, try fermenting at a slightly warmer temperature in the ideal range.

Keep your SCOBYs healthy.

If you have followed all of the above steps and nothing is working, the problem may be your SCOBY.

The bacteria and yeast balance may be out of whack, or your SCOBY may be unhealthy.

Did you purchase a bad SCOBY from someone?

Maybe you used this SCOBY at one point with flavorings instead of pure tea? Whatever happened, it’s easy to find reputable sources selling SCOBYs online.

We recommend getting a replacement if nothing else has worked for you. 

What is forced carbonation?

Many big kombucha brands (and several homebrewers wanting kombucha “on tap”) produce carbonation through kegging.

Essentially, F2 is done in either an open (cloth) or closed (airtight) environment for flavoring. The liquid is then poured into a keg and hooked up to a C02 tank, where carbon dioxide is then forced into the beverage.

When people refer to kombucha having natural carbonation, this means that they went through the F2 process without a keg, letting the fermentation and yeasts naturally create effervescence. 

Natural vs. forced carbonation

There are some differences between natural carbonation and carbonation as a result of kegging.

For example, take soda or beer… These beverages contain machine-made bubbles from forced carbonation.

Artificial bubbles tend to stick to the side of the glass more, have a harder and more bitter taste in the mouth, and are more uniform. Natural carbonation produces bubbles that are more interconnected, producing a fizz with a softer, more delicate mouthfeel.

Whatever method you choose to carbonate, we hope you get the right amount of bubbles.

Happy brewing!