Kombucha is a fermented tea beverage, beloved for its tangy flavor, potential health benefits, and effervescence. The fermentation process, which is powered by a SCOBY (Symbiotic Culture of Bacteria and Yeast), involves multiple phases where the yeast and bacteria work together to transform sweet tea into a probiotic-rich drink. Whether you’re a kombucha newbie or a seasoned home brewer, understanding the key phases of fermentation will help you produce a consistent, delicious brew every time. 

In this guide, we’ll walk you through the fundamentals of the kombucha fermentation process, focusing on the first fermentation (F1), second fermentation (F2), and an optional but exciting third fermentation (F3) for flavoring and carbonation perfection. You’ll also find helpful resources linked throughout to dive deeper into each phase. 

The First Fermentation (F1) 

The first fermentation is where the magic begins. During F1, you combine sweetened tea with your kombucha SCOBY and starter tea. Over a period of about 7-12 days, the yeast and bacteria in the SCOBY feast on the sugar in the tea, producing various acids, gases, and probiotics. 

Curious about the detailed steps? Check out our Guide to First Fermentation, which explains exactly how to prepare your sweet tea, add the SCOBY, and set up your fermentation vessel for the best results. 

What to Expect During First Fermentation 

As the first fermentation progresses, you may notice some strange yet normal things happening in your brew—like the formation of a new SCOBY layer, brown stringy yeast strands, or changes in the color and taste of your kombucha. 

Feeling nervous about whether your brew is on track? Head over to What to Expect During First Fermentation for a breakdown of the typical signs that your kombucha is fermenting properly. 

Knowing When Your Kombucha is Ready to Drink or Bottle 

After about 5-7 days of fermenting, your kombucha should start tasting tangy and slightly less sweet. But how do you know exactly when it’s ready to move on to the second fermentation—or if you’d prefer to drink it straight away? 

Visit When is Kombucha Ready to Drink/Bottle? to find out how to taste-test your brew, measure its acidity, and decide when to either bottle or enjoy it right after F1. 

The Second Fermentation (F2): Flavoring & Carbonation 

The second fermentation is where your kombucha develops its fizz and flavor. After removing the SCOBY, you can add fresh fruits, herbs, or juices to your kombucha and seal it in airtight bottles for 2-4 days. This is when carbonation builds up, giving your kombucha that satisfying fizz. 

Want to know more about how to flavor your kombucha and get it bubbly? Be sure to check out our comprehensive Guide to Second Fermentation: Flavoring & Bottling. 

The Optional Third Fermentation (F3) 

Some brewers like to take the second fermentation one step further with a third fermentation. This phase involves splitting the second fermentation process into two: one for flavoring and the other for carbonation. After infusing your kombucha with fruit or herbs, you strain it and then re-bottle it for another round of carbonation. 

For more detailed steps on how to separate your second fermentation into these two distinct phases, take a look at our Third Fermentation guide. 

Final Thoughts 

The kombucha fermentation process is straightforward, but it does require attention and care to yield the best results. From the initial steps of first fermentation, through flavoring and bottling in the second fermentation, to optional advanced steps like the third fermentation, mastering each phase will ensure you create kombucha that’s delicious, healthy, and perfectly fizzy. 

If you’re ready to get started or want to learn more about each phase, be sure to explore the linked resources above. Happy brewing!