Kombucha is a fermented, slightly carbonated, sweet-sour tea, that is used because of its suspected health benefits, especially in the gastric metabolism, as it contains probiotics. Kombucha is produced by fermentation of sugar tea using a symbiotic (group-beneficial) culture of bacteria and yeast, which is usually called Scoby (S.C.O.B.Y- symbotic culture of bacteria and yeast) and sometimes mother (mother) or sponge (shroom). The yeast component generally includes Saccharomyces cerevisiae
that ferments sugars into alcohols, and the bacterial component almost always includes Gluconobacter xylinus
that oxidizes alcohols into acetic acid and produce bacterial cellulose from sugars.
(May A, Narayanan S, Alcock J, Varsani A, Maley C, Aktipis A. Kombucha: a novel model system for cooperation and conflict in a complex multi-species microbial ecosystem. PeerJ. 2019;7:e7565. Published 2019 Sep 3. doi:10.7717/peerj.7565)
Kombucha is prepared in larger glass, metal or plastic containers. The Bokashi Organko of the first generation can be used for this purpose, as it offers a large volume for tea and a convenient tap at the bottom. In this short recipe I will describe my way of preparing kombucha in the Bokashi Organko. You can freely choose from the other recipes available online that might be more preferable to you. Two links to recipes are included: https://www.thekitchn.com/how-to-make-kombucha-tea-at-home-cooking-lessons-from-the-kitchn-173858
In the process of kombucha preparation, there is a chance of mold contamination so make sure to follow the guides regarding cleanliness and work with clean containers in a clean enviroment.
The main ingredient of kombucha is the symbiotic culture that is present in the form of a wet biofilm, which forms on the surface of the tea. This biofilm is actually bacterial cellulose, that serves as a protection boundary from intruders. The biofilm, also reffered to as Scoby, mother or tea shroom is used as a starter culture that initiates the fermentation process.You can buy the Scoby online, or by asking around.
Once we have the scoby, we can start preparing kombuch. First we prepare sweetened tea. The concentration of sugar should be between 50 and 120 g per 1 liter of tea and the concentration of tea should be 1 to 2 tea bags per 1 liter of water. This is just an advice and not a law to obey. Through time with experimenting you will find your optimal concentration. It is advised to use filtered or botteled water, but I have not stumbled upon any problems while using regular tap water.
Dissolve the sugar in boiling water and add your desired tea. After the tea is ready, take out the tea bags and let it cool to room temperature. Pour the tea in a cleaned Bokashi Organko and add your Scoby. Cover the top of the container with a rag, cloth piece or anything that permits gasses and blocks larger particulates. You can also leave the lid slightly opened on one side. Place the container in a safe, dim or dark and relatively warm place. The ambient temperature should be between 20 °C and 30 °C.
The fermentation runs faster at higher ambient temperatures and vice versa. Leave the tea to ferment from one to three weeks or more. Speaking from my own experience, I find two weeks to be the ideal fermentation time for my taste. The shorter the fermentation time, the sweeter the kombucha and the longer the fermentation time, the more sour it gets.
After the fermentation time is done, pour the kombucha directly into a glass or a smaller container for storage. You can also cool the drink for a more refreshing effect. You will most likely encounter stringy particles in your kombucha. These are aglomerates of bacteria, yeast and cellulose. You can remove them by filtrating the tea. It is recommended that you keep some kombucha and use it for storing scobys. You can divide the scoby into several smaller parts and store them in individual containers with a small amount of kombucha and addition of water and a few spoons of sugar. Growth of the scoby takes more time, up to 5 weeks.
Let my recipe serve you as a help with your preparation of kombucha. I urge you to experiment, use your imagination and above all, use common sense.
You will surely be able to resolve various uncertanties and questions with a short search on the web.