How to Tell When Kombucha is Done Fermenting
How Do I Know When My (First Ferment) Kombucha is Done Fermenting?
Guides on brewing kombucha usually tell you that it will be done in 6 – 30 days. This is quite a window period! The reason that the time frame for kombucha brews to mature in is so variable is because the fermentation process happens at a rate which is influenced by temperature, ingredients SCOBY health etc.
Generally you can know that if you are brewing in cold temperatures you will experience slower ferments that if you are brewing in warm temperatures, if you are using complex forms of sucrose (such as molasses or brown sugar) you can expect slower ferments, and if your culture has lost its vitality or is compromised this will also retard or halt fermentation.
But how do you know when it’s actually finished?
Gauging Fermentation Maturity
Fortunately the kombucha itself will begin to tell you when it is starting to mature. Keep in mind that the point of maturity is also dependent on your personal taste. You need to decide whether you want to have a stronger and more sour kombucha to drink, or a sweeter and milder version.
The One Week Rule
There is one golden guideline to follow when deciding when to harvest your kombucha, and that is the 7 day rule. According to the booch boffins, the organic acids and other nutrients which are responsible for kombucha’s reputation as a health drink only start to build up and accumulate after 7 days of fermentation have passed. So regardless of how quickly your brew is maturing, if you want to get the full complement of acids, enzymes, pro-biotics and vitamins, you should allow for at least a week of fermentation.
Other than this rule of thumb, there are some other signs by which you can gauge fermentation maturity. After 7 days have passed since the start of your fermentation – check for the following:
The smell of your brewing kombucha will let you know how far along it is. If your batch still has a sweet smell to it, then it is definitely not that far along in the fermentation process. However if it is starting to take on a tangy smell like vinegar, then things are moving along. Once the sharp acid smell is quite strong, your batch should be about ready!
Often, what happens as fermentation takes place is that the liquid in your brewing kombucha will lighten in color. This is because the yeasts are proliferating, and a fair amount of them float free in the tea. This can even cause kombucha to start to look cloudy. If you are noticing extreme cloudy-ness in your brews and want to find out more, have a look at LINK. The other thing that is happening is that if you are using black tea, or some other tea which is dark in color, for your sweet tea base, then as fermentation is taking place, the tannins in the tea are being consumed by the microbes. This also results in a lightening in color of your brew, and indicates that a decent level of fermentation has taken place.
The taste of your kombucha is the ultimate sign of how far along the fermentation is. The more sour the taste the more mature it is. If the batch still tastes very sweet, then it can definitely be left for longer. The easiest way to taste your kombucha is to insert a straw down the side of the vessel and suck up a sip. This way you can conveniently check it as often as you want to, and lessen the chances of it getting overly sour for your liking.
- Ph level
If you have some ph testing strips you can also use these to check the ph level of your brewing kombucha, and from this know how far it is. They say that if kombucha has reached a ph of 3 -2.5, then adequate fermentation has taken place. While you can usually taste whether your brew is getting sour and it is not necessarily critical to purchase ph strips for this, it might be a good idea to get some to test the ph at which you start off your batches. Kombucha recipes always call for the addition of starter liquid and spirit vinegar before leaving your new brews to ferment. This is because foreign bacteria and mold find it more difficult to take hold din a brew which is slightly acidic. Sometimes what can happen is that you use enough starter liquid, but it might be from a mild brew which is not acidic enough to bring the ph of your new batch down low enough at the start of fermentation to protect it until the microbes start their acidifying process. This is why it can be a good idea to check the ph in the beginning. Ph strips can be bought at your local pharmacy, or even ordered online. For easier determination of the ph level, you can also use an electric ph meter which will give you the ph number right away.
If you are brewing from a Continuous Brew System the Kombucha may ferment much faster (within a week). There is also a higher level of organic acids due to the mix of old kombucha that stays concentrated at the top of the brew.
What A Mature Brew Looks Like
If you are wondering if your brewing kombucha is almost ready, and you see that your brewing kombucha has the following elements going on, then you can be pretty sure that you can stop it any time.
- Brewing kombucha is pale in color
- SCOBY baby growth is happening and may be fully formed on the top of the container
- There are bubbles collecting on the sides of the brewing vessel and under the SCOBY
- Brewing kombucha has a vinegary smell
- The brew tastes sharp/tart/sour
Remember that the most important factor in determining whether or not your kombucha is ready to bottle is if it has reached the sweet/sour balance which you like. Remember if you like your kombucha on the sweet side, you can always stop it a little early and do a second ferment.
A second ferment allows you to let the brew mature a bit more without it getting overly sour, can up the carbonation, and at the same time allow you to add extra sweetening and flavoring without damaging the SCOBY.
For more on second ferments check out this post How To Make Second Ferment Kombucha (And Why You Absolutely Should).