Kombucha (kahm-BOO-chuh) is a fermented tea drink that probably originated in ancient China over two thousand years ago. The active culture which transforms the tea into kombucha is a complex Symbiotic Culture (or Colony) of Bacteria and Yeast which is held together in a thick, gelatinous biofilm. That’s a mouthful, so it’s commonly referred to by its acronym– SCOBY (SKOH-bee). It is rubbery and slippery, resembling the texture of a squid. It may also be called a kombucha culture, pellicle, zoogleal mat (impress your friends!), biofilm, mother or mushroom (although that last term is not quite accurate, because even though the yeast that comprises the colony are in the fungus family, they are not mushrooms).
Fermenting Containers and Primary fermentation
When looking for a fermentation vessel in which to make kombucha, select a non-porous, non-metallic material. Glass or ceramic work best. Plastic is okay, but some people prefer to avoid all plastic when fermenting. The SCOBY organisms need air. And the wider the container, the bigger the SCOBY can grow. When considering the diameter of a vessel, think Texas, not Manhattan.
Brewing Safely and pH
When you start your brew, sweet tea has a pH of about 5. In order to make the brew safe (that is, less prone to pathogenic microbes), you need to decrease the pH (that is, make it MORE acidic) to at least 4.6 at the beginning of the fermentation. That’s why it’s important to add a cup of mature kombucha to the starting tea. Once fermentation starts, the pH will continue to lower.
The pH, or measure of acidity, of finished kombucha should be around 3 to 3.5. At a minimum, it should drop to 4.6 in order to be considered safe. If you’re brewing at home, you can use pH strips to measure pH. It’s not super precise– if you’re brewing commercially or want more accuracy, you can obtain a pH meter.
Technique and Recipe
- 15 cups/3.5l (1 gallon less one cup) filtered water
- 10 tea bags or 10 teaspoons loose-leaf tea- any combination black, green, white, oolong, or pu-erh
- 1 cup/250 ml raw sugar (6.05 oz./200g by weight) sugar (refined white, or raw, but SCOBY prefers refined)
- 1 SCOBY (kombucha culture), 4-5 oz/110g or larger by weight
- 1 cup/250ml starter liquid (mature kombucha from a prior batch)
- (Optional) Flavorings (e.g. berries, fresh fruit, fruit juice, coconut water, herbs, ginger, etc.)
- 1 one-gallon/4L or larger glass jar or ceramic container (preferably with spigot at bottom, but not essential)
- Bottles to hold secondary ferments; pint-, quart-, or half-gallon sized-- bottles with tightly sealable caps, such as growlers, recycled mineral water bottles, or Grolsch-style swing-top bottles
- Swatch of cloth to cover the opening-- dish towel, tea towel, or paper coffee filter to cover the container's opening (not cheesecloth--flies can get through!)
- Rubber band
- Funnel (for bottling)
- NOTE: You want the new SCOBY to form as large in diameter as possible. It forms at the top of the liquid, so if you're using a one-gallon container, be sure you fill the container to just below the neck of the jar (no higher). You might not use the full gallon of sweet tea. You can either brew a little less tea than shown in the recipe, use the extra for another purpose, or even reserve for the next round of 'buch-making.
- Boil 1 quart of filtered water (in a tea kettle or 1-gallon or larger pot).
- Add tea bags (or if using loose tea, add tea to muslin bags or tea ball) to pot.
- Pour boiling water into pot. Add tea. Let steep for 10-15 minutes.
- Remove tea bags from pot. Add sugar and stir to dissolve.
- Pour remaining (unheated) filtered water into pot. Wait until the temperature drops to 100°F/38°C or below (otherwise you might kill the SCOBY). Tea is now ready
- Dispense tea into the glass or ceramic container.
- Rub your hands with vinegar or some of the starter liquid before handling SCOBY. Carefully add the SCOBY to the jar. Pour the starter liquid from the SCOBY on top of the contents.
- Cover with a cloth and secure with a rubber band. Store in a dark, well-ventilated area (keep out of direct sunlight). If using a transparent container, wrap a towel around it to minimize light.
- Give it some good vibes, and your newly created universe will prosper!
- Taste a bit after 7 days by dispensing some from the spigot. If using a container without a spigot, gently insert a straw into the jar (pushing the SCOBY aside). If it's too sweet, let it ferment longer. If you like the taste, it's ready for secondary fermentation and bottling (see next section). If you don't plan on a secondary fermentation, then move it to the fridge (to stop further fermentation) and enjoy!
- If it's too tart, then adjust the time next batch. If it's WAY TOO TART, then you can use it as vinegar.
- Add various flavorings to a clean glass bottle (that has either a swing top or one with a cap which can tighten.)
- Top with plain mature kombucha. Leave no more than ½" of head space in the neck of the bottle. Close tightly.
- Ferment an additional 1-7 days in the bottle, depending on the weather (cooler= longer, warmer=shorter). Note that carbonation will build up, so burp bottles occasionally (over the sink) to release gas buildup.
- Move to refrigerator and enjoy (or swap with your fellow Fermenters)!
- When you like the taste and texture (i.e. bubbles), move to refrigerator.
- Serve chilled. Enjoy in moderation.
Secondary fermentation (aka “Flavor Time”)
After the primary fermentation, flavoring and bottling (aka the secondary fermentation) is when you can really get creative with your ‘booch! You can use any combination of fresh fruit, fruit juice, veggies, ginger or other herbs and spices. Remember: a little goes a long way, but you should still play around with the quantities needed to achieve the desired level of sweetness or strength. Some ingredients will lend more carbonation. Here are just a few combinations we’ve tried.
Kombucha Flavor Gallery
Keeping Flies Out
You can craft a simple fly trap to lure vinegar flies away from the good stuff.
Where to get a SCOBY
- Mail Order: From a Kombucha specialist. I got my original culture from Kombucha Kamp and love it! It has made dozens of babies. They ship nationwide, too (Disclosure: I am an affiliate for Kombucha Kamp, meaning I get a small percentage of sales made if you click these links and buy from them).
- From a health-food store: Many local or regional brands now offer starter kits.
- Craigslist or local classified ads- People are always giving them away (you’ll know why after your first batch!)
- Ask for one on our Facebook page (indicating where you are located). Chances are other Fermenters in your area will be happy to give you one.
Storing SCOBY babies/ Taking a Break
If you decide to take a break from making kombucha, or you have extras (because a new SCOBY is made each time you make a batch), you can store your SCOBY (always at room temperature– never in the refrigerator!) in a little of the reserved liquid from the last batch you make. It doesn’t need much to survive, just enough to keep it wet. You can even build a SCOBY hotel by adding multiple cultures to a single container into a “hotel”, like so:
How much should you drink?
Kombucha, like any other fermented food, should be taken in moderation. While it is good for us (being a much healthier alternative to soda drinks), it is acidic, which can upset your stomach. It also contains sugar and caffeine (although it is believed the SCOBY consumes most of the caffeine, leaving about 1/4 the amount in an equivalent portion of brewed tea). There can be “too much of a good thing.” I’ve read that 4 to 8 ounces, twice a day (for a max daily intake of 16 ounces/2 cups) is a safe limit. Personally, I only drink max 8 ounces a day (and not every single day). You’ll have to experiment and pay attention to your own body, and as always, Trust your Senses.