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How to Flavour Kombucha: A Second Fermentation Guide

Learn how to flavour kombucha in the second ferment: fruit, herbs and spices, bottle sizes, headspace, burping and safe carbonation, step by step.

Published 6 min read
On this page
  1. Short answer
  2. What second fermentation does
  3. What you need
  4. Flavour options
  5. Step by step (per 500 ml bottle)
  6. Bottle safety
  7. Why is kombucha only in glass bottles?
  8. What flavours to add to kombucha?
  9. Can I add alcohol to my kombucha?
  10. Is 1 kombucha a day too much?
  11. Recipes to try
  12. Troubleshooting

Short answer

Flavour kombucha after the first ferment is finished. Add fruit, juice, herbs or spices to sealed bottles, then leave them at room temperature for one to five days. The sugar in the flavouring feeds the yeast, which makes carbon dioxide. Because the gas is trapped, pressure builds, so burp the bottles daily, use pressure-rated bottles and leave some headspace.

What second fermentation does

The first ferment turns sweet tea into tart, mostly still kombucha. The second ferment, often called F2, is where most of the fizz and much of the flavour come from. Before you bottle, remove the SCOBY and set aside a cup or two of the brew as starter for the next batch.

Sugar and yeast make the fizz. Fruit, juice and some herbs add sugar, so they also add fizz. Plain kombucha with no added sugar will carbonate much more slowly, if at all.

What you need

  • Finished first-ferment kombucha, unflavoured and not refrigerated
  • Pressure-rated bottles, usually swing-top (flip-top) glass, in 500 ml or 750 ml sizes
  • A funnel and a fine sieve for straining later
  • Your flavourings: fresh, frozen or pureed fruit, a juice, herbs or spices
  • A clean plastic drink bottle to use as a pressure gauge, if you have one

Flavour options

  • Fruit: berries, pineapple, mango, stone fruit, apple and pear. Frozen fruit gives up its flavour quickly. Smaller pieces give more flavour.
  • Juice: 100% juice, not from concentrate. Use a small amount, as juice is concentrated sugar.
  • Herbs: mint, basil, lemon balm, and a little lavender.
  • Spices and roots: fresh ginger, turmeric, cinnamon, and cayenne in small amounts.
  • Citrus: juice or thin peel. Pure citrus juice can taste sharp if you use too much.

A rough guide for a 500 ml bottle is about 2 to 4 tablespoons of chopped or pureed fruit, or about 2 tablespoons of juice. Start at the low end and taste.

Step by step (per 500 ml bottle)

  1. Wash the bottle in hot water with dish soap, rinse well and let it dry, or use a food-safe sanitiser.
  2. Add the flavouring. Mash soft fruit or add pieces, along with any herbs or spices.
  3. Pour the kombucha in through a funnel. Leave about 2.5 cm (1 inch) of headspace, and no more than about 5 cm (2 inches).
  4. Seal the bottle tightly.
  5. Leave it at room temperature, out of direct sun, for one to five days. Warm rooms go faster.
  6. Burp it once a day: open the lid slightly over a sink to release pressure, then close it again. Squeeze the plastic gauge bottle to judge how firm the pressure is.
  7. Once it is as fizzy as you like, chill it well before opening. Cold holds the gas in better.
  8. Strain before serving if you prefer no bits.

Bottle safety

Bottles can burst or spray, so take the following seriously.

  • Use bottles designed for carbonation. Do not use thin decorative bottles, and check the gaskets and seals.
  • Burp every day. Sugary flavours such as berries, mango and pineapple build pressure faster.
  • If a bottle is very hard, vent it slowly over a sink with a towel over the lid.
  • Open cold bottles over a sink, with the lid turned away from your face and from children. Cold bottles gush less.
  • Keep bottles out of direct sun and away from heat, and discard any that are cracked or leaking.

Why is kombucha only in glass bottles?

It is not only glass. Glass is common because it holds pressure well, is easy to clean and does not react with the acid. Some commercial kombucha is sold in cans or kegs. For home brewing, use pressure-rated glass and keep a plastic bottle as a gauge.

What flavours to add to kombucha?

Most flavours that taste good in a drink work. The most reliable choices are fruit with plenty of natural sugar, then herbs and spices for extra interest. Some ideas:

Can I add alcohol to my kombucha?

Adding spirits or wine turns the drink into an alcoholic drink. It is a different product with different risks, and it should not go into a bottle that is still fermenting. If you want a splash, add it when you serve. If you would rather ferment the alcohol in, that is a separate process with its own yeast and safety steps, covered in how to homebrew kombucha beer. Alcohol-based bitters also add a little alcohol, so read the label. For a related question, see the cayennade recipe.

Is 1 kombucha a day too much?

There is no single safe amount for everyone. Most brewing and health guides suggest starting with around 100 ml a day and building up slowly. Pregnant or breastfeeding women, young children, people with a weakened immune system and people with kidney disease should check with a doctor first. For kidney questions, see is kombucha good for kidneys.

Recipes to try

Troubleshooting

  • Not fizzy: the usual causes are a leaky seal, too little sugar, a cold room or not enough time. See why your kombucha is not fizzy.
  • Too fizzy: chill the bottle sooner, burp more often and use less sugary fruit.
  • Mould or yeast film: a new SCOBY can look hazy or wrinkled. Fuzzy or dry spots, especially blue-green, black or orange ones, are mould. If you are unsure, see is it mold or a healthy SCOBY? Discard any batch with mould. A white, wrinkled film on the surface is kahm yeast, which is not usually harmful but signals a weak brew, so start again.

If you are wondering how long to keep the SCOBY between batches, see how long a SCOBY can sit in starter liquid.

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