The Science Behind Kombucha

Natalie Petit | Associate Editor

Kombucha: it’s fizzy, sweet, and sour all at once. Some people love it and some people don’t. But what exactly is it and how is it made? This cider-like drink is essentially fermented tea that is produced by using a culture of bacteria and yeast (called SCOBY, or Symbiotic Colony of Bacteria and Yeast). SCOBY acts as a starter; this means that the process to make a batch of kombucha with the original SCOBY yields a second SCOBY that can be used to make more kombucha. To make kombucha, the SCOBY is combined with water, tea (any flavor works), kombucha from a previous batch, and sugar. This mixture is then covered with a cloth and allowed to sit for a few weeks at room temperature in a process known as first fermentation. During fermentation, the bacteria and yeast consume the sugar and produce carbon dioxide. Afterwards, other components such as spices and fruit juice can be added to the mixture if additional flavoring is desired. The mixture is fermented for about five days, after which the kombucha is ready for consumption!

Because kombucha is a fermented drink, it contains live bacteria and yeasts, as well as other components such as organic acids, B vitamins, and antioxidants. Typical 8 ounce servings contain ~30 calories and 20 grams of sugar. Most kombuchas have 0.5-3.0% alcohol content as a byproduct of fermentation. For reference, light beer has about 4.2%. Although kombucha contains trace amounts of alcohol, it is not considered an alcoholic beverage, and an ID is not required to buy it at a store. Today, there are many discussions surrounding the impact of kombucha on our health, with some proponents of kombucha stating that this drink improves gut health, the immune system, and digestion. However, very little research has been done to verify health related claims, although it is recommended that it be consumed in moderation. The main risk involved in brewing kombucha is infection. Because yeast and bacteria are used, there is the possibility of creating an environment where the microbes can reproduce. The best way to avoid infection is to wash all of the equipment with soap and water and sterilize the jars and lids that will be used. Kombucha that is sold in stores has already passed health code regulations and is safe for the public.

Kombucha has existed for thousands of years. It was first referenced in 220 BCE in Northeast China. Its name, however, comes from a Korean physician named Dr. Kombu who introduced the drink to Japan 200 years later. The tea was brought to Europe in the 20th century through trade routes and has continued to grow in popularity over the decades. In the United States, kombucha was originally sold by individuals through grassroots distribution. Today, it can be found in almost any store and continues to flourish in pop culture, with PepsiCo choosing to purchase a top kombucha brand, KeVita, in 2016. It is clear that kombucha will be fascinating tea-loving consumers for a long time to come. 

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