Many folks who make kombucha complain that they just aren’t getting enough carbonation during the secondary fermentation. Here, I try to break down the factors you can check to help improve your fizzy game.
Food (for the yeasty beasties)
In order to create more carbonation, you need to have a sufficient amount of sugar in the bottle. That sugar source could be the initial sugar from the primary fermentation (more on that below), or additional sugar you add (usually fruit juice, which contains mostly fructose). The yeasts ferment (since you are closing the bottle, there’s no air for the beasts to breathe) and convert the sugar into carbon dioxide, ethanol and water. If adding more fruit juice, we typically suggest a 1:16 ratio of juice to kombucha. That would mean if you are filling a 16 oz bottle, use 1 oz. (2 tablespoons) of juice and fill the rest with kombucha. See our scary warning below about adding TOO MUCH additional sugar to the bottle.
If you aren’t adding enough sugar, this can manifest as lack of bubbles (since the yeasts have nothing to eat in the bottle).
You could add more raw or table sugar (sucrose) to the bottle, but we prefer to use this opportunity to make it more flavorful, so we usually opt for fruit juice. Need flavoring ideas? We got a lot of them.
If you don’t want to add more sugar, an alternative is to use kombucha secondary fermentation that’s less “ripe”, meaning start the secondary a few days before you would normally drink it. It will be a bit too sweet to drink at this point, but you are using those residual sugars to feed the yeasts enough to create carbonation.
Ginger root (despite being low in sugar) is also known to help create carbonation (although we’re not sure exactly how). Add a few julienned slices of fresh ginger root to the bottle for flavor and a little boost.
Kombucha is happiest fermenting in temperatures between 72° and 84°F (22° and 29°C), and secondary fermentation works best especially in the warmer half of that range. If it’s too cold in the room where you are fermenting your bottles, it may take longer to ferment and build up carbonation, if at all. TIP: Try setting your kombucha crock and bottles on top of a seedling mat (Amazon affiliate link) to increase the fermentation temperature by about 10°F. This multi-tasking device works great for both primary and secondary fermentation.
You need to have the correct vessel to hold in the carbon dioxide gas the yeasties create (and burp) while they’re doing their thing. Here is our list of container types in descending order of their awesomeness at fizz creation.
If you’re using a container that isn’t completely airtight, then one reason you may not be keeping the fizz is because it’s escaping out into the atmosphere. Double-check that.
Most beer brewing stores carry swing top bottles.
Fermentation, of course, teaches us the virtue of patience. If your ‘booch just isn’t bubbly, it’s possible you haven’t given it enough time to build up carbonation.
You can check how much carbonation has built up by gently opening the bottles (over a sink, in case it’s feisty) and observing how much pressure there is. If it’s a lot, close the lid and chill it, then try again. The carbonation won’t go away completely, but the lower temperature will calm things down a bit and make it easier to manage.
Of course it would be irresponsible of us to leave out a very important point. You are dealing with a force of nature here. It can sometimes be unpredictable. You must take caution when fermenting in closed containers, especially those made of glass.
Ready to learn more? Take one of our classes!
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