Want the basics first? What a SCOBY is, what it looks like and where to get one is covered in What is a SCOBY?. This article goes deeper: into the microbiology, and into how BOUCHE controls fermentation at brewery scale. Whether kombucha is healthy is covered in Is kombucha healthy?

Kombucha starts with simple ingredients. BOUCHE Kombucha is made from filtered water, black and green tea, regional beet sugar and our own liquid SCOBY culture of yeasts and bacteria. Four base ingredients, countless variables.

The culture is kombucha in concentrated form, comparable to a well-kept sourdough. It carries the foundational acidity and sets the entire microbial process in motion. So far, that sounds like chemistry. What follows is craft.

What the SCOBY does

Inside the fermentation tank, yeasts and bacteria form a symbiotic community, known as a SCOBY: Symbiotic Culture of Bacteria and Yeast. The yeasts process the sugar, producing CO₂ and trace amounts of alcohol. Lactic and acetic acid bacteria follow, converting that alcohol into organic acids and shaping the characteristic flavour profile of the kombucha.

This interplay cannot be rushed. It follows its own rhythm, responding to temperature, culture composition and the quality of the tea. Brewing good kombucha means learning to listen to that process.

How BOUCHE controls fermentation at brewery scale

At home, kombucha usually ferments openly: a solid SCOBY mat floats in a jar under a breathable cloth. That works for a few litres, but not for a drink that has to taste the same across thousands of bottles. So BOUCHE ferments closed: with our own liquid SCOBY culture instead of an open cellulose mat, in a 3,000 L aeration tank that supplies the culture with oxygen in a controlled way. No contact with ambient air, no risk from stray microbes, and an oxygen supply we steer rather than leave to chance.

Why we stabilise

Fermentation is by nature an open process. Left unchecked, kombucha keeps changing: more acidic, drier, less precise. For a drink brewed in Berlin and opened several weeks later, that is not an option.

BOUCHE ferments fully and fills in-house. The kombucha is centrifuged to clear yeast and sediment, and directly after filling it gets a short heat treatment, our flash stabilisation. This stops fermentation at the point where the flavour profile is most coherent. The organic acids and tea aromatics are preserved (the carbonation we add after fermentation, partly to hold the aroma). The live cultures from the tank are not: the finished bottle contains no living bacteria or yeast.

That is a deliberate choice, not a compromise. Stabilisation is the moment we decide: this is how it should taste. It also keeps the alcohol content reliably between 0.2 and 0.5% vol. and the flavour stable, whenever you open the bottle.

What is in the bottle

Every bottle of BOUCHE contains the flavour-giving results of fermentation: natural organic acids, polyphenols from the tea and low sugar, plus gentle carbonation. Live bacteria and yeast are not in it; they stay in the tank. The profile is stable because we chose the moment of stabilisation deliberately.

Whether cold or at room temperature, straight from the bottle or over a meal: BOUCHE tastes the way we brewed it. The craft is in the fermentation. The precision is in everything else.