Kombucha

Kombucha is the Western name for sweetened tea or tisane that has been fermented using a macroscopic solid mass of microorganisms called a "kombucha colony," usually consisting principally of Acetobacter-species and yeast cultures. It has gained much popular support within many communities, mentioned by talk show hosts and celebrities. The increase in popularity can be seen by the many commercial brands coming onto the retail market.

Biology of kombucha

The culture contains a symbiosis of Acetobacter and yeast, mostly Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii.

The culture itself looks somewhat like a large pancake, and though often called a mushroom, or by the acronym SCOBY, it is clinically known as a fungus.

History and etymology

The recorded history of this drink dates back to the Qin Dynasty in China. The Chinese called it the "Immortal Health Elixir," because they believed Kombucha balanced the Middle Qi and aided in digestion, allowing the body to focus on healing. Knowledge of kombucha eventually reached Russia and then Eastern Europe around the Early Modern Age, when tea first became affordable by the populace.

Russian "tea mushroom"

The process of brewing kombucha was introduced in Russia and Ukraine at the end of the 1800s, and became popular in the early 1900s. The kombucha culture is known locally as chayniy grib, and the drink itself is referred to as grib, "tea kvass" or simply "kvass", although it differs from regular "kvass" which is not made from tea and is generally fermented only with yeast and not the other bacteria which ferment tea to form kombucha.

Components

Kombucha contains many different cultures along with several organic acids, active enzymes, amino acids, and polyphenols. Final kombucha may contain some of the following components depending on the source of the culture: Acetic acid, which provides much anti-microbial activity; butyric acid, gluconic acid, glucuronic acid, lactic acid, malic acid, oxalic acid, usnic acid, as well as some B-vitamins.

Health effects

A review of the published literature on the safety of kombucha suggests no specific oral toxicity in rats, although other reports suggest that care should be taken when taking medical drugs or hormone replacement therapy while regularly drinking kombucha. It may also cause allergic reactions or other complications, such as hepatotoxicity, and one should discontinue use or consult a medical professional if complications arise.

Kombucha is also low in calories, and thus a good alternative to other beverages as beer, lemonade, and fruit juice. Because of this, home production of kombucha is increasing in popularity.

Claims

Advocates believe that kombucha helps by competing with endogenous microbes without toxic constituents, when it's cultivated carefully. Increased glucuronic acid conjugates in the urine after kombucha consumption may support this hypothesis.

Early chemical analysis of kombucha brew suggested that glucuronic acid was a key component of it, perhaps assisting the liver by supplying more of the substance during detoxification. But more recent analysis of kombucha offer a different explanation, as outlined in the book in Analysis of Kombucha Ferments by Michael Roussin. Roussin reports on an extensive chemical analysis of a variety of commercial and homebrew versions of kombucha, and finds no evidence of glucuronic acid at any concentration.

But Roussin suggests that another component may have health benefits

Reports of adverse reactions may be related to unsanitary fermentation conditions, leaching of compounds from the fermentation vessels, or "sickly" kombucha cultures that cannot acidify the brew. Cleanliness is important during preparation, and in most cases, the acidity of the fermented drink prevents growth of unwanted contaminants. If a culture becomes contaminated, it will most likely be seen as common mold, green or brown in color.

In Japan it became a popular drink in the 1970's to the early 1980's with claims of its health benefits; however, after careful analysis it was seen to have absolutely no benefits at all and thus disappeared from the store shelves.

Safety and contamination

As with all foods, care must be taken during preparation and storage to prevent contamination. Keeping the kombucha brew safe and contamination-free is a concern to many home brewers. Key components of food safety when brewing kombucha include clean environment, proper temperature, and low pH.

In every step of the preparation process, it is important that hands and utensils are dish soap clean so as not to contaminate the kombucha. For safety reasons, Kombucha should be brewed in food-grade glass containers only. Kombucha should not be brewed in lead crystal, ceramic, plastic, painted, or metallic containers including stainless steel, as the acidic solution can leach by-products into the finished product. Keeping cultures covered and in a clean environment also reduces the risk of introducing contaminants and bacteria.

Maintaining a correct pH is an important factor in a home-brew. Acidic conditions are favorable for the growth of the kombucha culture, and inhibit the growth of molds and bacteria. The pH of the kombucha batch should be between 2.5 and 4.5. A pH of less than 2.5 makes the drink too acidic for human consumption, while a pH greater than 4.5 increases the risk of contamination. Use of fresh "starter tea" and/or vinegar can be used to control pH. Some brewers test the pH at the beginning and the end of the brewing cycle to ensure that the correct pH is achieved.

If mold does grow on the surface of the kombucha pellicle, or "mushroom," it is best to throw out the batch and start over.

Additional observed effects

Aside from any possible health benefits, it can be intoxicating. It is generally characterized by mild euphoria, relaxation, and an overall sense of physical and mental well-being. Kombucha contains variable amounts of alcohol and caffeine, though the effects felt in drinking the beverage are disproportionately profound in comparison with the amount ingested, suggesting something more at work. Alcohol amounts vary from 0.5% to 1.5%, depending on anaerobic brewing time and proportions of microbe. Pasteur said that alkaline fermentation increases alcohol content. Commercial preparations are typically 0.5% for distribution and safety reasons. It can be hard to distinguish ale-fungus from kombucha.

Another possible cause of these effects is the psychoactive amino acid L-theanine, which is naturally present in tea. Stimulation of the circulatory and immune systems, and associated glandular releases, may also account for some of these effects. Some reports of more intense effects could be explained by toxins resulting from contamination of the culture.

See also

*Tibicos


All text of this article is available under the terms of the GNU Free Documentation License.