Kombucha

Kombucha (also tea mushroom, tea fungus, or Manchurian mushroom when referring to the culture; botanical name Medusomyces gisevii) is a fermented, slightly alcoholic, lightly effervescent, sweetened black or green tea drink commonly intended as a functional beverage for its supposed health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, or other flavorings are often added to enhance the taste of the beverage. The exact origins of kombucha are not known. It is thought to have originated in Manchuria where the drink is traditionally consumed, or in Russia and Eastern Europe. Kombucha is now homebrewed globally, and also bottled and sold commercially by various companies. Kombucha (also tea mushroom, tea fungus, or Manchurian mushroom when referring to the culture; botanical name Medusomyces gisevii) is a fermented, slightly alcoholic, lightly effervescent, sweetened black or green tea drink commonly intended as a functional beverage for its supposed health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, or other flavorings are often added to enhance the taste of the beverage. The exact origins of kombucha are not known. It is thought to have originated in Manchuria where the drink is traditionally consumed, or in Russia and Eastern Europe. Kombucha is now homebrewed globally, and also bottled and sold commercially by various companies. Kombucha is produced by fermenting sugared tea using a symbiotic culture of bacteria and yeast (SCOBY) commonly called a 'mother' or 'mushroom'. The microbial populations in a SCOBY vary; the yeast component generally includes Saccharomyces cerevisiae, along with other species; the bacterial component almost always includes Gluconacetobacter xylinus to oxidize yeast-produced alcohols to acetic acid (and other acids). Although the SCOBY is commonly called 'tea fungus' or 'mushroom', it is actually 'a symbiotic growth of acetic acid bacteria and osmophilic yeast species in a zoogleal mat '. The living bacteria are said to be probiotic, one of the reasons for the drink's popularity. Numerous implausible health benefits have been attributed to drinking kombucha. These include claims for treating AIDS, aging, anorexia, arthritis, atherosclerosis, cancer, constipation, and diabetes, but there is no evidence to support any of these claims. Moreover, the beverage has caused rare cases of serious adverse effects, including fatalities, possibly arising from contamination during home preparation. Therefore, the potential harms from drinking kombucha outweigh any unclear benefits, so it is not recommended for therapeutic purposes. The exact origins of kombucha are not known, although Manchuria is the likely place of origin. It may have originated as recently as 200 years ago or as long as 2,000 years ago. The drink is reported to have been consumed in east Russia at least as early as 1900 and from there entered Europe. Its consumption increased in the United States during the early 21st century. Having an alcohol content of less than 0.5%, kombucha is not a federally regulated beverage in the United States. Prior to 2015, some commercially-available kombucha brands were found to contain alcohol content exceeding this threshold, sparking the development of new testing methods. With rising popularity in developed countries in the early 21st century, kombucha sales increased after it was marketed as an alternative to beer and other alcoholic drinks in restaurants and pubs. In Japanese, the term kombucha (昆布茶, 'kelp tea') refers to a kelp tea made with powdered konbu (an edible kelp from the Laminariaceae family) and is a completely different beverage from the fermented tea usually associated with kombucha elsewhere in the world. The etymology of kombucha is uncertain; however, it is speculated that it is a misapplied loanword from Japanese. It has been hypothesized that English speakers mistook the Japanese word kombucha to mean fermented tea, when in fact, fermented tea in Japanese is called kōcha kinoko (紅茶キノコ, 'red tea mushroom'). The Merriam-Webster Dictionary maintains that the use of kombucha in the English language likely stems from the misapplication of Japanese words: konbucha, kobucha (which translate to 'tea made from kelp'), kobu, konbu (which mean 'kelp') and cha (meaning “tea”). The American Heritage Dictionary offers further insight into the etymology of kombucha, stating that it was “perhaps used by English speakers to designate fermented tea due to confusion or because the thick gelatinous film produced by the kombucha culture was thought to resemble seaweed.' The first known use in the English language of the word kombucha to describe “a gelatinous mass of symbiotic bacteria (as Acetobacter xylinum) and yeasts (as of the genera Brettanomycesand Saccharomyces) grown to produce a fermented beverage held to confer health benefits” was in 1944. A kombucha culture is a symbiotic culture of bacteria and yeast (SCOBY), similar to mother of vinegar, containing one or more species each of bacteria and yeasts, which form a zoogleal mat known as a 'mother'. There is a broad spectrum of yeast species spanning several genera reported to be present in kombucha culture including species of Zygosaccharomyces, Candida, Kloeckera/Hanseniaspora, Torulaspora, Pichia, Brettanomyces/Dekkera, Saccharomyces, Lachancea, Saccharomycoides, Schizosaccharomyces, and Kluyveromyces. The bacterial component of kombucha comprises several species, almost always including Komagataeibacter xylinus (formerly Gluconacetobacter xylinus), which ferments alcohols produced by the yeasts into acetic and other acids, increasing the acidity and limiting ethanol content. The bacteria of kombucha require large amounts of oxygen for their growth and activity. The population of bacteria and yeasts found to produce acetic acid has been reported to increase for the first 4 days of fermentation, decreasing thereafter. K. xylinus has been shown to produce microbial cellulose, and is reportedly responsible for most or all of the physical structure of the 'mother', which may have been selectively encouraged over time for firmer (denser) and more robust cultures by brewers.