The alcohol content of kombucha depends strongly on the circumstances of the fermentation. How much sugar was used? How long was the fermentation? How warm was it? Was a secondary fermentation added?
If you want to keep the alcohol content as low as possible, the following is recommended:
- Good air circulation reduces the alcohol content, as the acetic acid bacteria need oxygen to convert the alcohol. Therefore, it is good to make sure that your kombucha is not too far from the edge of the fermentation vessel and is only covered with a cloth.
- With secondary fermentation in closed bottles, on the other hand, a little more alcohol can build up, especially if sugar or sweet fruits are added again.
- Allow your kombucha to ferment at temperatures of 20 °C or cooler. When it is warmer the yeasts become more active compared to the bacteria.
- To reduce the alcohol-producing yeast content a little further, you can wash your Scoby with clean water before each new batch to remove the brown yeast streaks. In addition, you can pour off the brown sediment from yeasts in the fermentation vessel or remove it with the help of a coffee filter.
Normally, kombucha contains between 0.5 % and 1 % alcohol. This is about as much as can be found in a freshly squeezed orange juice or in overripe bananas.