The fermentation of kombucha closely resembles that of vinegar fermentation. First, the yeast convert sugar to alcohol, then, the bacteria convert alcohol to organic acids. While there are differences in the chemical composition and fermentation process between kombucha and vinegar, the general concept behind the two fold symbiotic fermentation of yeast and bacteria mirror one another.
WHAT MAKES KOMBUCHA TASTE LIKE VINEGAR?
The vinegar taste comes from the production of organic acids during the conversion of alcohol by bacteria. As these acids are synthesized, the kombucha becomes more acidic, lending to a harsher, more bitter flavor as the ferment progresses.
WHAT ACIDS ARE PRESENT IN KOMBUCHA?
There are three main organic acids formed during kombucha fermentation: acetic, glucuronic, and gluconic.
Acetic Acid: The defining acid in vinegar and the most abundant of acids in kombucha is acetic acid. It is derived from ethanol and is how it’s earned its other name, ethanoic acid.
Glucuronic Acid: Formed from glucose, glucuronic acid is a key building block for many of our bodily functions and is also important for the metabolic pathways for all living things.
Gluconic Acid: Also derived from glucose, gluconic acid is present in kombucha and also found naturally in honey, wine, & fruit. Its presence in our gut helps support the vitality of our microbiome.
IF YOU LEAVE KOMBUCHA LONG ENOUGH, DOES IT TURN INTO KOMBUCHA VINEGAR?
Vinegar is by definition >4% by volume acetic acid. During the traditional brewing of kombucha, the natural limiting alcohol production doesn’t allow enough alcohol for the bacteria to convert.
For kombucha to become kombucha vinegar there is an additional fermentation process to raise the alcohol content higher than the kombucha culture could do on its own.
CAN YOU REDUCE THE VINEGAR FLAVOR?
Yes! The vinegary flavor starts off weak in the beginning of the brew due to a small percentage of inoculum, about 10%. As the tea ferments, the organic acid production increases but does so steadily. You can monitor your kombucha by tasting it daily and deciding when the flavor balance is just right for you.
WAYS TO USE OVER-FERMENTED KOMBUCHA
If you’ve happened to allow your kombucha to ferment too long and find it hard to drink, there’s still ways to use it up!
Here are a few ideas:
-Use it as the pickling brine for vegetables or fruits
-Make sauces and salad dressings. The addition of a vinegar in a sauce is the secret to making the flavors shine–use your over-fermented kombucha to serve the same purpose!
-Blend it with a new batch of kombucha to reduce the bitterness
-Use it to make ricotta cheese
-Use it to start a sourdough starter
As you can see there are many different ideas of how to use over fermented kombucha and you can be as creative as you want to avoid tossing your beloved but over-soured brew.