Brew Your Own Kombucha

By Rachel Cook – April 1, 2021

If you’re wanting to learn how to make kombucha, it’s likely you’ve already tried the drink and are quite the kombucha enthusiast already. For those who haven’t, kombucha is a fermented tea that originated in the northeast region of China over 2,200 years ago.

In this particular process of fermentation, a symbiotic culture of bacteria and yeast (SCOBY) is required. Sucrose, popularly known as table sugar, is broken down into glucose by the yeast. After that, the bacteria can convert the glucose into other things. Komagataeibacter, also known as gluconacetobacter, is always the most abundant bacteria strain in the symbiotic culture and converts glucose into cellulose and fructose. Bacteria then convert the fructose into ethanol and carbon dioxide which breaks down further into acetic acid, giving it its vinegar-like flavor. As you can see from the diagram, bacteria also work to convert glucose into gluconic acid which is further converted to glucuronic acid by acetic acid bacteria.

While the vinegar-like flavor might be an acquired taste, part of what makes kombucha so popular is the allure of its health benefits. Originally, the drink was consumed in Traditional Chinese Medicine as an elixir of life. Since then, many studies have come out examining the fermentation process and health benefits, including probiotics, antioxidants, polyphenols and flavonoids. There are, however, no clinical studies performed on humans with published results. In a study published in the U.S. National Library of Medicine, “green tea was characterized by the most significant antioxidant properties, [and] slightly lower potential was observed for red and white tea types, whereas black tea featured the lowest values.” These antioxidants “act as free radical terminators, metal chelators, singlet oxygen quenchers or hydrogen donors,” which can help lower inflammation and support the immune system. The only thing to watch out for is the low pH. The acidity of kombucha prevents unwanted microorganisms from growing in the tea, but it can also cause stomach-upset, especially in those with gastrointestinal reflux or ulcers. 

What You’ll Need:

  • 1-gallon glass jar
  • Container (and strainer if using loose leaf tea)
  • Cotton cloth to cover the glass jar (a t-shirt, bandana, coffee filter or paper towel would work, too)
  • Rubber band
  • Flip-top bottles
  • Funnel
  • Tea: black, green, white or oolong tea (make sure to have at least 25% black or green tea)
  • ¾ cup cane sugar
  • SCOBY (symbiotic culture of bacteria and yeast)

Step 1: Brew the tea

  1. Bring 14 cups of water in a pot or electric kettle to a boil.
  2. Take the water off the heat and add ¾ cup of cane sugar. Stir until dissolved.  
  3. Steep 8 bags of your choice of tea, traditionally black or green, or two tablespoons of loose tea in the hot water. You can choose to steep the tea until the water cools for a stronger tea (which will be a few hours) or for the recommended brewing time of the tea (typically 3-5 minutes). The longer you steep, the more tannins are released, resulting in a more bitter-tasting tea. 
  4. Remove the tea bags or strain the tea and pour it into the 1-gallon jar. 

Or the shortcut method:

  1. Boil 4 cups of water in a pot or electric kettle.
  2. Take the water off the heat and steep 8 bags of tea or two tablespoons of loose tea in the hot water for 15 minutes.
  3. Remove the tea bags or strain the loose tea.
  4. Add ¾ of a cup of sugar to the tea and stir until dissolved. 
  5. Add 14 cups of room-temperature or cold water to the 1-gallon jar and then add the hot tea to the jar.

Step 2: Fermentation Part One (Yeast convert sugar into ethanol and bacteria convert ethanol into acid)

  1. Once the tea in the jar is between 70-90 degrees Fahrenheit, add 2 cups of starter tea and your SCOBY. If the tea is below 70 degrees, the bacteria will be dormant and the kombucha could mold. If it is above 90 degrees, the SCOBY will die. 
  2. Cover the jar with a clean cloth and secure with a rubber band. This will allow airflow into the jar but prevent dust and bugs from entering. 
  3. Let the tea sit at room temperature (70-85 degrees Fahrenheit) for about one week. Avoid moving it so as not to disturb the fermentation process. For a sweeter tea, begin to taste it around 5 days of fermentation. For a tarter tea, let sit and taste it around 7-9 days of fermentation. 

At this point in the process, you can be done if you are satisfied with your kombucha. Otherwise, you can move into the second phase of fermentation in which you flavor and carbonate your kombucha. 

Step 3: Fermentation Part Two

  1. IMPORTANT: Remove the SCOBY and 2 cups of kombucha from the 1-gallon jar, and set it aside. This is the starter tea necessary for brewing any future batches of kombucha. Learn more about how to store your SCOBY here
  2.  Add ¼–⅓ cup fresh fruit juice or puree to each 16 oz flip-top bottle using the funnel. The sugar from the fruit will enable more fermentation to occur. 
  3. Stir the kombucha in the jar to evenly distribute bacteria and yeast. This ensures a more even distribution of carbonation in each 16 oz flip-top bottle. 
  4. Using the funnel, pour the kombucha from the 1-gallon jar into each of the 16 oz flip-top bottles, leaving ½–1 inch of space between the kombucha and the top of the bottle. 
  5. Dry the tops of the bottles.
  6. Seal the bottles. 
  7. Store the bottles at room temperature for 2–3 days. There is risk of over-carbonation which may result in the bottle exploding. Keep this in mind when storing the bottle. 
  8. Move the bottles to the refrigerator to stop the fermentation process. Once chilled, test the kombucha to see if it is carbonated to your liking. Chilling the kombucha should also help keep it from fizzing over when opened. If the kombucha is not carbonated to your liking, move the bottles back to room temperature for another day or until satisfied. 

If you make kombucha, make sure to take a picture and tag us on Instagram @austinfit!

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