Kombucha Fermentation, How to tell if your kombucha is working?
So you’ve brewed your tea, added your culture, found a spot for it live… Now what? How do you know that it’s “working”?
While my best piece of advice is to trust that it is, there are a few signs to watch for to get some peace of mind. Testing the pH and using your sense of sight, smell and taste should give get a good idea that your booch is well on its way. Let’s go over how you can do this.
Reading Kombucha pH
Arguably the best indicator of a brew’s progression is its change or drop in pH. Taking a pH reading is a straightforward scientific way to see how your kombucha brew is fermenting. We will talk about acid production throughout this post. These beneficial acids can be detected through smell or taste, and can also be measured by testing the pH. As kombucha ferments, more acids are produced, and your brew becomes more acidic! If you’ve tested the starting pH, then come back a week later, and it has dropped, then you know that acids are being produced and your fermentation is occurring. It’s as simple as that.
The easiest way to test for pH is by using pH test strips in the acid range 0-6 like these. Kombucha should stay within this pH range, so targeting this range provides easy, accurate results. If you happen to have some for your aquarium or pool, they’ll work as long as they can read lower numbers. You could also get a pH meter, these provide very accurate readings, but you’ll have to calibrate it. So depending on your needs, for home applications, the strips may be easier.
Want to dive a little deeper on pH? Check out our post on kombucha pH Level.
Visual Changes During Fermentation:
The first to reveal themselves are typically the yeast.
Yeast cells flocculate during fermentation as a means of protection from alcohol (for a visual, picture how fish school to protect themselves from predators). The flocculation provides a visible manifestation of what would otherwise be impossible to see with the naked eye! If there’s alcohol present, this means that fermentation has occurred, and you will notice brown clumps or strings of yeast throughout your brew. They can be anywhere in the jar–they might attach to the SCOBY like the photo below, or sink to the bottom, or kind of chill somewhere in the middle. More on yeast flocculation here!
The next visual clue is pellicle growth on the surface.
The most noticeable byproduct produced during the fermentation is bacterial cellulose, which develops and thickens on the surface with time. It is lovingly referred to as the “mother” or “baby,” sometimes as the “mushroom” or “SCOBY”–really it is none of these things, just cellulose synthesized by bacteria during fermentation. The time this takes to develop varies with a strong correlation to temperature. The lower the temperature, the longer this formation will take. Nonetheless, it is a clear sign that fermentation has occurred. If you want to dig deeper on the subject, check out our post on kombucha pellicle growth.
The final visual indicator is a change in color
During the fermentation, the SCOBY feeds on tannins in the tea. This results in a brew that is lighter in color than it started.
This change is more gradual and becomes noticeable over weeks, not days.
Changes in Aroma:
A vinegary aroma will develop as the fermentation progresses, starting mild and then ending strong.
Each ferment is a little different, but when fermenting at the proper kombucha temperature by day 6-12, you will often be able to detect a distinct vinegary tinge. This change of smell is contributed to the formation of beneficial acids by the bacteria, most notably acetic, gluconic, glucuronic acids. Acetic acid is the same acid in vinegar and is why the smell is so close. The longer you let a brew ferment, the more acids will build-up, and the smell will get stronger as well.
Changes in Taste:
The taste should resemble the smell–starting off sweet but ending with a vinegary dominance.
As the acids build up in the ferment, it will develop more vinegar tones. If you let it over ferment, it just means that the acids have built up to the point that it becomes hard to drink. At this point, you have a mild kombucha vinegar (think drinking vinegar shots). I recommend starting to taste at the beginning of the brew and periodically throughout so that you can monitor and get used to the progression. Tasting often allows you to find the sweet spot where you enjoy both drinking it and the health benefits.
While these indicators are typical, it’s essential to keep in mind that each brew is allowed to be a little different. If you’re not noticing pellicle growth, or not noticing a change in color, you shouldn’t assume that it is not fermenting. If you’re having any trouble with your brew, feel free to send us a message, and we can troubleshoot together.