If you’ve brewed kombucha at home, you’re probably familiar with the natural carbonation process that occurs as the live yeasts consume sugar and convert it into carbon dioxide. This carbonation happens during both first fermentation (F1) and second fermentation (F2). But did you know that even after you refrigerate your kombucha, you can still increase its carbonation by leaving it at room temperature for a while? 

Here’s how to re-carbonate flat kombucha and make your brew fizzier, even after it seems to have gone flat. 

Why Does Kombucha Go Flat? 

Kombucha can lose its carbonation for a few reasons: 

  • Insufficient second fermentation: If your kombucha didn’t get enough time in a sealed bottle during F2, it may not have built up much carbonation before you refrigerated it. 
  • Opened bottle: Once you open a bottle, some of the carbonation naturally escapes, and over time, your kombucha may go flat. 

Luckily, you can bring back some of that lost fizz! 

How to Re-carbonate Kombucha After It’s Gone Flat 

If you find that your kombucha is flat after opening or if it didn’t carbonate as much as you hoped after second fermentation, here’s what you can do: 

1. Take the Kombucha Out of the Fridge 

  • Even if your kombucha has been chilled, the yeasts will wake up once it’s brought back to room temperature. Simply remove your sealed bottles from the fridge and let them sit at room temperature for a day or two. The live yeast will start eating the sugars in the kombucha again and produce more carbon dioxide, which will boost the fizz. 

2. Let It Sit at Room Temperature 

  • Leave the bottles sealed at room temperature for 24-48 hours. The longer you leave them out, the more carbonation will build up. Just be sure not to leave them out for too long, as over-carbonation could lead to exploding bottles! 

3. Chill Before Opening 

  • Once the kombucha has sat at room temperature long enough to re-carbonate, put the bottles back in the fridge to chill before opening them. Cold liquids hold carbonation better, so refrigerating them first will minimize the risk of it fizzing over or making a mess when you open the bottle. 

What If You Only Drank Half a Bottle? 

If you opened a bottle, drank half, and then noticed the rest has gone flat, you can still re-carbonate it! Just follow these steps: 

  1. Seal the Bottle Tightly: If you have a good, airtight cap, seal the bottle tightly after you’ve had your fill. 
  2. Leave It at Room Temparature: Let it sit at room temperature for at least a few hours. The yeasts will start producing carbon dioxide again, bringing back some of that lost fizz. 
  3. Refrigerate Before Finishing: Just like before, chill the bottle again before drinking the rest to retain as much fizz as possible. 

What About Store-Bought Kombucha? 

This method works best for homemade kombucha because the live yeast and bacteria in your brew continue to work even after refrigeration. However, it may not work as well for store-bought kombucha. Many commercial brands use yeast inhibitors or other processes to halt fermentation, which can prevent re-carbonation. Some brands labelled as “raw” might still work, but it’s hit or miss depending on how the product is made. 

Conclusion 

If your kombucha is a little flat, don’t worry! You can easily re-carbonate it by letting it sit at room temperature for a few hours or days, depending on how much fizz you want. Just be sure to refrigerate it again before opening to prevent any spills. Enjoy the refreshed, bubbly goodness of your homemade kombucha!