From tea to glass: the fermentation steps, the role of the SCOBY, and the Hopfield method for integrating hops.
Kombucha is made in 6 steps: preparing the sweetened tea, inoculating with the SCOBY, primary fermentation (F1) for 7 to 21 days, tasting and adjustment, secondary fermentation in bottles (F2), then refrigeration. At Hopfield, an additional dry-hopping step is added at the end of F1, without heat, to preserve all the aromas.
The SCOBY (Symbiotic Culture Of Bacteria and Yeast) is a gelatinous disc made of bacterial cellulose, housing lactic acid bacteria, acetic acid bacteria, and yeasts in symbiosis.
Its texture resembles rubbery jellyfish. Its role: consume the sugar via the yeasts, produce alcohol, then transform it into organic acids via the bacteria. This double fermentation gives kombucha its personality.
The SCOBY reproduces with each fermentation by forming a new layer, it can be used indefinitely.
A concentrated tea infusion is prepared, then sugar is dissolved in it. Typical ratio: 60–80 g of sugar per liter of water, 5–8 g of tea per liter.
The choice of tea is crucial: green tea will give a lighter, more floral kombucha, black tea a more robust and tannic one.
The cooled tea is poured into the fermentation vessel, then the SCOBY and approximately 10% of the volume in starter liquid, already fermented kombucha, are added. This acidic liquid protects the culture from contaminants from the start.
The fermenter is covered with a breathable cloth and placed at room temperature, away from direct light. For 7 to 21 days, the SCOBY works: it consumes the sugar, produces bubbles and organic acids.
Midway through and before bottling, we taste. Too sweet = insufficient fermentation. Too acidic = fermentation gone too long. This is where the brewer steps in with their palate, the fundamental difference from industrial kombucha.
The SCOBY is removed. The filtered kombucha is transferred into airtight bottles with a little sugar and aromatics (fruits, hops, spices). In a sealed bottle, residual yeasts produce CO₂ with nowhere to escape, this is how natural carbonation is born.
In the cold (4–6°C), fermentation slows dramatically. The kombucha refines itself, aromas blend. A week in cold bottles generally improves the flavour profile.
At Hopfield, we developed an approach inspired by craft brewery dry-hopping : adding hops cold at the end of F1, without heat, to preserve all volatile aromas.
Article written by the Bio Brasseurs team