MSU Extension Safe Food & Water

Kombucha is a fermented tea beverage touted as having many health benefits, and has been consumed in China and Japan since 220 B.C. While it can be purchased commercially, many people make their own at home, and there are countless recipes online. The main components are black tea, sugar and a symbiotic culture of bacteria and yeast (SCOBY).

Food safety issues with kombucha are not common, but there are some risks to be aware of. According to the International Association for Food Protection, these risks can be categorized as biological, chemical or allergy hazards.

Biological Hazards

The introduction of foodborne pathogens can happen at any point in food preparation, so good hygiene and sterilization practices are necessary. This includes having clean hands and work surfaces at all times. Make sure to sterilize containers and utensils used to make and store the kombucha and only use boiled water to make the tea.

Another biological control step is the fermentation process itself. The process of fermentation lowers the pH of the liquid from greater than or equal to 5, to approximately 2.5 over the course of 7 to 10 days. This lowering of pH is a good way to reduce potential pathogens. Using pH test strips or a digital pH meter to test the pH throughout the process is recommended. If a pH of 2.5 has not been reached by day 10, the liquid should be thrown out.

The last area where biological contamination can occur is via the SCOBY. This group of living organisms is susceptible to growth of mold and fungi that could produce dangerous toxins. Always inspect your SCOBY for physical mold, fungi, or abnormal coloration. Throw it away if it displays any abnormalities.

Chemical Hazards

One potential chemical hazard is associated with the vessels used to ferment and store kombucha. Because of its low pH, it is recommended that kombucha be made and stored in glass containers because other types of materials could be subject to damage or leaching from exposure to low pH, such as iron. Also, use containers marked as food-grade.

Another chemical hazard of kombucha comes from excess consumption of the final product. How much is too much? That depends on your own body chemistry and health history. The main risk is lactic acidosis, which is an accumulation of acid in the blood. People with compromised immune systems, heavy alcoholic drinkers and pregnant women might be more susceptible.  The recommended dose of kombucha is one-half cup per day, but most commercial kombucha is sold in much larger quantities, and it is not common public knowledge that this beverage is intended to be consumed in small amounts.

Allergen Hazards

While no illness case reports thus far have been directly linked to allergic reactions, some people have reported shortness of breath and tightness of the throat after consuming kombucha. People who have sensitivities to mold, fungi and yeast may be more vulnerable to allergic-type reactions.

Kombucha is generally considered a safe beverage from a food safety perspective if it is made, handled and stored properly. Michigan State University Extension recommends being aware of the potential hazards, and following the outlined steps to prevent them.