Bottling & second fermentation
Make your kombucha sparkle
A second fermentation in the bottle can add fizz and new flavours to your kombucha. The yeasts remain active and produce carbon dioxide. Use suitable bottles, keep track of added sugar and check your brew regularly.
What is bottling?
Bottling means transferring your kombucha to clean bottles. In a sealed bottle, yeasts convert available sugars into alcohol and carbon dioxide (CO₂). Some of that gas dissolves in the drink and creates fizz. The speed varies between batches, and the alcohol content can increase during this stage.
What bottles can you use?
Choose clean, undamaged bottles that the manufacturer rates for carbonated drinks and bottle conditioning. Both the bottle and its closure must be suitable for pressure.
-
Flip-top bottles: use a type intended for carbonated drinks and check the glass, closure and gasket before each use.
-
Crown-cap bottles: choose suitable beer bottles or other pressure-rated bottles with matching caps. A crown cap is not a pressure-relief valve: excessive pressure can also break these bottles.
Monitor carbonation with either type. Residual sugar, fruit or juice additions, temperature and time all influence pressure. Occasional opening does not guarantee safe pressure between checks. Avoid damaged bottles and decorative glassware.
What changes during the second fermentation?
The second fermentation mainly develops flavour and carbonation, while the microorganisms remain active. Their numbers and the compounds they produce can also change. The outcome depends on your culture, ingredients, temperature and fermentation time.
More live microorganisms does not automatically mean a greater proven health benefit. Kombucha is a fermented drink; calling a product probiotic requires specific evidence. Read more in the biochemistry of kombucha.
Bottling: step by step
-
Start with brewed kombucha. Complete the first fermentation using the instructions supplied with your starter. Keep the culture and enough starter liquid for your next batch. Bottle the remaining kombucha; do not simply dilute it with fresh tea.
-
Choose a flavour. Start with a small trial batch and a modest amount of fruit, juice or herbs. Fruit and juice also add sugar. Do not automatically add priming sugar: a standard beer dose is not a universal recipe for kombucha.
-
Fill suitable bottles. Use clean, intact bottles intended for carbonated drinks. Follow the manufacturer’s directions for filling and sealing.
-
Monitor carbonation from the first day. Fizz may develop in roughly one to three days at room temperature. This is an indication, not a guaranteed safe storage period. Warmth and more available sugar can speed up fermentation. A small sample in a suitable PET soda bottle can help track pressure development, but does not guarantee safe pressure in other bottles.
-
Chill promptly and open carefully. Refrigerate once there is enough carbonation, or earlier if you are unsure. Chill thoroughly and open slowly, pointing away from your face. Refrigeration slows fermentation without stopping it completely. Keep bottled kombucha refrigerated.
Find your flavors!
Start with one flavouring and note what you add. This helps you learn what works with your tea and repeat a batch you enjoy.
-
Ginger: fresh and spicy.
-
Fruit or a little juice: for a fruity note. Account for the extra sugar.
-
Herbs and spices: try mint, basil or a small piece of cinnamon.
-
Tea: the tea in your first fermentation has a big influence on the finished drink. Compare green and black tea in separate batches.
Use clean ingredients and equipment. Fresh and dried ingredients can both influence fermentation and flavour; dried does not automatically mean safer.
Found a flavour combination you love? Share your brew on Instagram with @BiomeBrew.
Further reading on preparation and storage: Colorado State University Extension: Understanding and Making Kombucha.