Secondary fermentation is essential when making kombucha at home. It's the final step that makes the fermented tea drink fizzy and flavorful, and more like kombucha you find at the store. This is also an opportunity to add flavor to your kombucha with fruits, ginger, or juice to personalize it to your taste. The process is easy, takes a few days, and results in a better-tasting, sparkling kombucha.
What Is Secondary Fermentation?
When your home-brewed kombucha has reached the basic sweet and tart flavor you enjoy, it's time to bottle it. It probably won't be as effervescent and sparkling as you expect, though. Secondary fermentation is the process of forcing carbonation in the bottle to produce bubbly kombucha. At the same time, the flavor will continue to develop and you can add flavoring ingredients.
How to Secondary Ferment Kombucha
- To begin secondary fermentation, remove the scoby from your kombucha, reserve about two cups of the mother tea, and place both back into the fermentation jar. The remaining kombucha is the portion you will bottle. Filter it through cheesecloth if you want to remove any floating bits first.
- Use a funnel to fill the bottles, leaving some space for air at the top of each. Opinions differ, though one inch of headspace is a good start, and you'll learn what works best as you brew more kombucha.
- Let the bottled kombucha sit at room temperature for one to 10 days. The fermentation time depends on the room temperature, the kombucha batch, and any additives you introduce. For instance, some fruits, such as raspberries, will speed up carbonation. During this time, you might notice some kombucha growth—floating strands, sediment, or even the partial development of a scoby.
- Test one bottle of kombucha for fizziness and flavor by pouring a small amount into a glass. When it's to your liking, place the bottles in the refrigerator for storage. It's not necessary to strain kombucha, though you can filter out the fruit and kombucha particles before refrigerating or wait until it's time for a drink.
Cold storage will not stop fermentation, but it will significantly slow it down. The flavor and carbonation will continue to develop over time, and you can drink it at any point. It's best within a few months, after which it will likely be too sour.
Glass vs. Plastic Bottles
Some home kombucha brewers use glass beer bottles capped as if brewing beer, or cork enclosures. Flip-top glass bottles with plastic seals are popular, convenient, and easy to reuse. Avoid metal lids as it can negatively affect the taste of the kombucha.
Glass requires more attention. During secondary fermentation, there is the possibility of an explosion if too much pressure builds up. It can be a stinky mess that, for some people, has required extensive cleaning and a fresh coat of paint on the walls.
One way to avoid this problem is to "burp" the kombucha bottles—open them up briefly every one or two days to relieve pressure, then seal them back up. Once in the refrigerator, burp bottles every few weeks. The kombucha will still carbonate. Some kombucha brewers are against burping entirely because they feel it releases too much carbon dioxide.
Plastic bottles are good for beginners and shouldn't require burping. Squeeze some of the air out of the bottle before securing the lid so the sides collapse a bit. The plastic will become firm as it carbonates, making it easy to know when fermentation is done.
Add Flavor to Kombucha
kombucha is delicious with additional flavors, including fruits, herbs, and spices. The flavoring ingredients are added to the bottle during secondary fermentation. How much you add is a personal choice, and a few tips will help you get started:
- For most fresh or frozen produce, add about 1 cup to each bottle.
- As long as the pieces fit into the bottle's neck, they typically slide out when straining. Shake the bottle or use a chopstick to prod stubborn fruit or ginger out of the bottle.
- When adding a juice, use about 1 to 2 ounces of juice for every pint (16 ounces) of kombucha.
- Use a combination of fresh produce with juice for easy custom flavors.
- Hard spices, such as a cinnamon stick, will swell as it soaks up liquid and become nearly impossible to remove. Add smaller pieces rather than a full stick to thin-necked bottles.
- Add whole sprigs of herbs such as rosemary or thyme. For tender herbs, including mint or basil, consider infusing the flavor into a juice or puréeing the flavoring ingredients. Strain the purée before adding to kombucha.
How to Make Ginger Kombucha
Ginger is a natural complement to kombucha and it's often paired with a splash of lemon juice. To make this infusion, simply cut fresh ginger root into matchsticks that will slip inside the bottle's neck. Unless you're using organic ginger, it's best to peel it first.
Alternatively, make a "ginger juice" concentrate by steeping 1/2 cup of fresh chopped ginger in 2 cups of boiling water. Stir in a little lemon juice or sugar, if you'd like. Let the mix cool completely, then strain out the ginger and add the juice to the kombucha.
How to Make Fruit Kombucha
Fruit-flavored kombucha is equally delicious and easy. Use fresh or bottled fruit juice, or a concentrate, to create a slightly sweeter kombucha. Rinse fresh fruit before adding it to the bottle, and cut large fruit into matchsticks. There's no need to thaw frozen fruit.
- Blueberry, blackberry, cranberry, and raspberry are popular kombucha flavors. Larger berries may need to be halved to fit in the bottle.
- Elderberry adds delicious and unique flavor.
- Cranberry-orange-ginger is good for winter, while blueberry-lemon-ginger is a fantastic combination for summer. Apple-cinnamon kombucha is a seasonal fall blend.
- Mushier fruits like bananas, strawberries, and peaches may require additional straining. Puréeing them adds flavor and slightly thickens kombucha.
- Have fun with tropical fruits, such as mango, papaya, pineapple, and pomegranate. Tropical fruit juice blends offer great possibilities, too.
- Try favorite herb-fruit pairings, such as mint and lime, strawberry and basil, or rosemary and grape.