Kombucha is a fermented tea which has many purported health benefits. I make and drink it because: it may be a probiotic; it may contain beneficial vitamins; I want to drink green tea regularly; and I enjoy the taste, including the mild “bite” it provides. I usually mix it with something else, either fruit juice or plain green tea. For a more detailed description of kombucha and its history, see this article.

The process of making kombucha involves simply allowing a combination of yeast and bacteria to convert sugar into carbon dioxide and vinegar. The yeast/bacteria combination is called a SCOBY, which is an acronym for “symbiotic combination of bacteria and yeast”. The sugar used must be an actual sugar, not just a sweetener. Table sugar (sucrose) works best. Other sugars, such as honey, maple syrup, brown rice syrup, molasses or agave syrup will work, however, they have additional considerations. First, the timing will be different for each sugar. Also, the sugar must be sterile, in order to not interfere with the SCOBY. Lastly, the flavor of the kombucha will be different.
For the simplest kombucha, here’s the list of tools and ingredients.

Equipment

  • Container for fermenting, at least three quarts capacity
  • Spoon for stirring
  • Air permeable cloth like cheesecloth
  • Rubber band or string to hold the cloth in place
  • Air-tight container for the new SCOBY and starter kombucha

Ingredients

  • Green tea
  • Sugar
  • SCOBY

One of the most important considerations for making kombucha is that everything be kept very clean. You can handle the SCOBY and even put your hands in the kombucha (to retrieve the SCOBY) but your hands must be very clean — free of soaps and perfumes and lotions. The container and the spoon and anything else which will come in contact with or contain the kombucha or the SCOBY must be very clean. Also, since kombucha is rather acidic (around a pH of 3) the container and utensils should be either food grade glass or stainless steel. They most definitely shouldn’t be plastic or reactive metals.

It’s possible, but not trivial,  to grow your own SCOBY from a bottle of commercial kombucha tea. It’s easier to buy a SCOBY from your grocer. It’s best to get a SCOBY from a friend or someone local. The SCOBY should be a milky white color, it should hold together well and shouldn’t have any black spots or fuzzy molds on it. The SCOBY should also include some kombucha from a previous batch, to keep the SCOBY moist and to provide the acid for starting the new batch of kombucha.

Begin the process by brewing two quarts of your favorite tea (green or black are fine). Pour the tea into the container, cover it with the cloth and allow it to return to room temperature (about 20 C or 70 F). If your container is clear glass, place it so it won’t be in direct sunlight.

Once the tea is at room temperature, stir in two cups of sugar. Ensure that the sugar is completely dissolved.

Separate the SCOBY from its starter kombucha. You can place the SCOBY on a clean plate or in a clean bowl. If you’re dextrous, you can hold the SCOBY, but it will drip. Pour about a cup of the starter kombucha into your tea and sugar mixture; stir it well.

If you know which side of the SCOBY was the top, gently place it on the tea/sugar/starter mixture in the same orientation. Some times it will float and sometimes it won’t — it’s not really important. Cover the container with the cloth and secure it with the rubber band or the string. I’ve found that a paper towel works best. The container must not be airtight but the cloth or paper must be sufficiently dense to keep out any dust and small insects. Place the container somewhere that it won’t be disturbed and where it can remain about 70 degrees F. If the ambient temperature is cooler, the kombucha will require more time to ferment. If the temperature is consistently higher, it will require less time.

After about one week, take a look at the SCOBY. It should have floated to the surface, or a new SCOBY should have formed on the surface. A new SCOBY may be very thin. It should also be milky white and smooth. Carefully look for signs of black or fuzzy mold. If you do find signs of mold, it’s safest to assume that your kombucha was somehow contaminated. All of the contents should be discarded, everything must be washed very thoroughly and the process should be started again.

If everything else looks good, it’s time to taste the kombucha. Use a clean plastic drinking straw or something which will allow you to reach beneath the SCOBY and extract enough of the kombucha to taste. You’re checking three things:

  1. The acidity
  2. The sweetness
  3. The general flavor

It should taste or feel acidic. If it does not, there’s a risk of the kombucha being contaminated by the wrong bacteria. The acidity can be corrected by the addition of a bit of apple cider vinegar.

If it still tastes sweet, that indicates that there’s still sugar to feed the SCOBY. You can stop at this point and have a sweeter kombucha or continue to ferment and have a thicker SCOBY, more probiotics and vitamins, and a “livelier” kombucha.

The flavor is either going to be something you enjoy (or learn to enjoy) or something you’ll want to adjust later by mixing the finished kombucha with something else.

If you want more acidity and less sweetness, let the kombucha ferment longer. The cooler the ambient temperature, the longer the kombucha must ferment. If the acidity and sweetness are acceptable, wash your hands well and clean your new SCOBY container. Remove the SCOBY from the kombucha and place it in the new jar. You may be able to separate the SCOBY into several layers, each of which can subsequently be used for the next batch(es) of kombucha. Place at least one cup of the new kombucha with the new SCOBY and close the container. You must fully cover the new SCOBY with the new kombucha. The new SCOBY(s) can be preserved in the fridge for at least a month. You’ll need to return them to room temperature before you use them in a new batch of kombucha.

Transfer the remaining new batch of kombucha to clean bottles or jars. For safety, these bottles must be able to withstand a bit of internal air pressure, in case the kombucha continues to ferment after being bottled. You can decide to either fill each bottle with just kombucha or to leave room in each bottle for the addition of another flavoring liquid.

It’s now time to enjoy your batch of kombucha, to share it with friends and to even share your SCOBY. It’s not necessary to use an entire SCOBY to make a batch of kombucha.

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