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Kombucha (also tea mushroom, tea fungus, or Manchurian mushroom when referring to the culture; Latin name ''Medusomyces gisevii'') is a fermented, lightly
effervescent Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from that release. The word effervescence is derived from the Latin verb ''fervere'' (to boil), preceded by the adverb ''ex''. It has the same li ...
,
sweetened {{Wiktionary, sweetener A sweetener is a substance added to food or drink to impart the flavor of sweetness, either because it contains a type of sugar, or because it contains a sweet-tasting sugar substitute. Many artificial sweeteners have been ...
black tea drink commonly consumed for its purported health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, fruit or other flavorings are often added. Kombucha is thought to have originated in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, where the drink is traditional. By the early 20th century it had spread to Russia, then other parts of Eastern Europe and Germany. Kombucha is now
homebrewed Homebrewing is the brewing of beer or other alcoholic beverages on a small scale for personal, non-commercial purposes. Supplies, such as kits and fermentation tanks, can be purchased locally at specialty stores or online. Beer was brewed dom ...
globally, and also bottled and sold commercially. The global kombucha market was worth approximately billion . Kombucha is produced by symbiotic fermentation of sugared tea using a ''
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
culture of bacteria and yeast'' ( SCOBY) commonly called a "mother" or "mushroom". The
microbial A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
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 In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...
to
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...
(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 An osmophile is a microorganism adapted to environments with high osmotic pressures, such as high sugar concentrations. Osmophiles are similar to halophiles (salt-loving organisms) in that a critical aspect of both types of environment is their low ...
yeast species in a zoogleal mat ". The living bacteria are said to be probiotic, one of the reasons for the popularity of the drink. Numerous health benefits have been claimed to correlate with drinking kombucha; there is little
evidence Evidence for a proposition is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from field to field. In epistemology, evidenc ...
to support any of these claims. The beverage has caused rare serious adverse effects, possibly arising from contamination during home preparation. It is not recommended for therapeutic purposes.


History

Kombucha most likely originated in the Bohai Sea district in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. The drink was consumed in Russia and from there entered the rest of 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. According to Grand View Research, Kombucha had a global market size of billion and this was expected to grow to billion by 2027.


Etymology and terminology

In Japanese, the term refers to a kelp tea made with powdered '' konbu'' (an edible kelp from the family Laminariaceae) 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 . Webster's Dictionary maintains that the use of ''kombucha'' in English likely stems from the misapplication of Japanese words: ''kombucha, kobucha'' 'tea made from kelp', ''kobu, konbu'' 'kelp', and ''cha'' 'tea'.
The American Heritage Dictionary ''The American Heritage Dictionary of the English Language'' (''AHD'') is an American English, American dictionary of English published by Boston publisher Houghton Mifflin Harcourt, Houghton Mifflin, the first edition of which appeared in 1969. ...
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 ''Brettanomyces'' and ''Saccharomyces'') grown to produce a fermented beverage held to confer health benefits" was in 1944.


Composition and properties


Biological

A kombucha culture is a
symbiotic culture of bacteria and yeast Symbiotic culture of bacteria and yeast (SCOBY) is a culinary symbiotic fermentation culture ( starter) consisting of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast which arises in the preparation of sour foods and beverages s ...
(SCOBY), similar to
mother of vinegar Mother of vinegar is a biofilm composed of a form of cellulose, yeast and bacteria that sometimes develops on fermenting alcoholic liquids during the process that turns alcohol into acetic acid with the help of oxygen from the air and acetic acid b ...
, containing one or more species each of bacteria and yeasts, which form a
zoogleal mat A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular pol ...
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'', ''Kluyveromyces, Starmera, Eremothecium, Merimbla, Sugiyamaella.'' The bacterial component of kombucha comprises several species, almost always including the acetic acid bacteria ''
Komagataeibacter xylinus ''Komagataeibacter xylinus'' is a species (biology), species of bacteria best known for its ability to produce cellulose, specifically Bacterial cellulose, bacterial cellulose. History and taxonomy The species was first described in 1886 by Adri ...
'' (formerly ''Gluconacetobacter xylinus''), which ferments alcohols produced by the yeasts into
acetic Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...
and other acids, increasing the acidity and limiting ethanol content. 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'' produces
bacterial cellulose Bacterial cellulose is an organic compound with the formula produced by certain types of bacteria. While cellulose is a basic structural material of most plants, it is also produced by bacteria, principally of the genera ''Acetobacter'', Sarcina ( ...
, 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. The highest diversity of Kombucha bacteria was found to be on the 7th day of fermentation with the diversity being less in the SCOBY. Acetobacteraceae dominate 88 percent of the bacterial community of the SCOBY. The acetic acid bacteria in kombucha are aerobic, meaning that they require oxygen for their growth and activity. Hence, the bacteria initially migrate and assemble at the air interface, followed by excretion of bacterial cellulose after about 2 days. The mixed, presumably symbiotic culture has been further described as being lichenous, in accord with the reported presence of the known lichenous natural product
usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...
, though as of 2015, no report appears indicating the standard cyanobacterial species of
lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.gluconic acid Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid. In aqueous solution at neutral pH, gluconic acid fo ...
and acetic acid. In addition, kombucha contains enzymes and amino acids, polyphenols, and various other
organic acid An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are rel ...
s which vary between preparations. Other specific components include ethanol (see below),
glucuronic acid Glucuronic acid (from Greek γλεῦκος "''wine, must''" and οὖρον "''urine''") is a uronic acid that was first isolated from urine (hence the name). It is found in many gums such as gum arabic (c. 18%), xanthan, and kombucha tea and ...
, glycerol, lactic acid,
usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...
(a hepatotoxin, see above), and B-vitamins. Kombucha has also been found to contain vitamin C. The alcohol content of kombucha is usually less than 0.5%, but increases with extended fermentation times. The concentration of alcohol specifically ethanol increases initially but then begins to decrease when acetic acid bacteria utilize it to produce acetic acid. Over-fermentation generates high amounts of acids similar to vinegar. The pH of the drink is typically about 3.5.


Production

Kombucha can be prepared at home or commercially. Kombucha is made by dissolving sugar in non-chlorinated boiling water. Tea leaves are steeped in the hot sugar water and discarded. The sweetened tea is cooled and the SCOBY culture is added. The mixture is then poured into a sterilized beaker along with previously fermented kombucha tea to lower the pH, this technique is known as "backslopping". The container is covered with a paper towel or breathable fabric to prevent insects such as fruit flies from contaminating the kombucha. The tea is left to ferment for a period of up to 10 to 14 days at room temperature (18°C to 26°C). A new "daughter" SCOBY will form on the surface of the tea to the diameter of the container. After fermentation is completed, the SCOBY is removed and stored along with a small amount of the newly fermented tea. The remaining kombucha is strained and bottled for a secondary ferment for a few days or stored at a temperature of 4 °C. Commercially bottled kombucha became available in the late 1990s. In 2010, elevated alcohol levels were found in many bottled kombucha products, leading retailers including Whole Foods to temporarily pull the drinks from store shelves. In response, kombucha suppliers reformulated their products to have lower alcohol levels. By 2014, US sales of bottled kombucha were $400 million, $350 million of which was earned by Millennium Products, Inc. which sells
GT's Kombucha George Thomas Dave is an American businessman and founder and CEO of the kombucha company GT’s Living Foods. In the late 1990s, he was the first to put kombucha on store shelves, and his company currently owns 40% of the U.S. kombucha market. ...
. In 2014, the companies that make and sell kombucha formed a trade organization, Kombucha Brewers International. In 2016,
PepsiCo PepsiCo, Inc. is an American multinational food, snack, and beverage corporation headquartered in Harrison, New York, in the hamlet of Purchase. PepsiCo's business encompasses all aspects of the food and beverage market. It oversees the manuf ...
purchased kombucha maker KeVita for approximately $200 million. In the US, sales of kombucha and other fermented drinks rose by 37 percent in 2017. Beer companies like Full Sail Brewing Company and Molson Coors Beverage Company produce kombucha by themselves or via subsidiaries. As of 2021, the drink had some popularity in India's National Capital Region, partly due to its success in the west. Indian kombucha makers include Bhu Kombucha, Stoked Kombucha and Toyo Kombucha.


Hard kombucha

As of 2019, some commercial kombucha producers sell "hard kombucha" with an alcohol content of over 5 percent.


Health claims

Many people drink kombucha tea for its purported health benefits. These include claims for treating
AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual m ...
, aging, anorexia nervosa, arthritis, atherosclerosis, cancer, constipation, and diabetes. There have not been any
human trials This page is a list of the episodes of '' The Outer Limits'', a 1995 science fiction/dark fantasy television series. The series was broadcast on Showtime from 1995 to 2000, and on the Sci Fi Channel in its final year (2001–2002). Series overvi ...
conducted to assess its possible biological effects, and the purported health benefits resulting from its biological activities have not been demonstrated in humans. A 2003
systematic review A systematic review is a Literature review, scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from publ ...
characterized kombucha as an "extreme example" of an unconventional remedy because of the disparity between implausible, wide-ranging health claims and the potential risks of the product. It concluded that the proposed, unsubstantiated therapeutic claims did not outweigh known risks, and that kombucha should not be recommended for therapeutic use, being in a class of "remedies that only seem to benefit those who sell them". As of 2019, the drink's physiological effects on people are largely unknown.


Adverse effects

Reports of adverse effects related to kombucha consumption are rare, but may be underreported, according to the 2003 review. The
American Cancer Society The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into six geographical regions of both medical and lay volunteers operating in more than ...
says that "Serious side effects and occasional deaths have been associated with drinking Kombucha tea". Because kombucha is a commonly homemade fermentation, caution should be taken because pathogenic microorganisms can contaminate the tea during preparation. Adverse effects associated with kombucha consumption include severe hepatic (liver) and renal (kidney) toxicity as well as
metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...
. At least one person is known to have died after consuming kombucha, though the drink itself has never been conclusively proven as the cause of death. Some adverse health effects may arise from the acidity of the tea causing acidosis, and brewers are cautioned to avoid over-fermentation. Other adverse effects may be a result of bacterial or fungal contamination during the brewing process. Some studies have found the hepatotoxin
usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...
in kombucha, although it is not known whether the cases of liver damage are due to usnic acid or to some other toxin. Drinking kombucha can be harmful for people with preexisting ailments. Due to its microbial sourcing and possible non-sterile packaging, kombucha is not recommended for people with poor immune function, women who are pregnant or nursing, or children under 4 years old. It may compromise
immune responses An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including viruses, bacteria, parasites, and fungi which could ...
or stomach acidity in these susceptible populations. There are certain drugs that one should not take at the same time as kombucha because of the small percentage of alcohol content. A 2019
systematic review A systematic review is a Literature review, scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from publ ...
confirmed the numerous health risks, but said "kombucha is not considered harmful if about 4 oz 20 mLper day is consumed by healthy individuals; potential risks are associated with a low pH brew leaching heavy metals from containers, excessive consumption of highly acidic kombucha, or consumption by individuals with pre-existing health conditions."


Other uses

Kombucha culture, when dried, becomes a leather-like textile known as a
microbial cellulose Bacterial cellulose is an organic compound with the formula produced by certain types of bacteria. While cellulose is a basic structural material of most plants, it is also produced by bacteria, principally of the genera ''Acetobacter'', ''Sarcin ...
that can be molded onto forms to create
seamless clothing Seamless may refer to: * Seamless (company), an online food ordering company * "Seamless", a 2015 song by Sabrina Carpenter from '' Eyes Wide Open'' * "Seamless", a song by American Head Charge from the 1999 album ''Trepanation'' and the 2001 alb ...
. Using different broth media such as coffee, black tea, and green tea to grow the kombucha culture results in different textile colors, although the textile can also be dyed using other plant-based dyes. Different growth media and dyes also change the textile's feel and texture. Additionally the SCOBY itself can be dried and eaten as a sweet or savory snack.


See also

*
Jilly Juice Jilly Juice is a quackery, quack pseudomedicine in the form of a fermentation, fermented drink that is falsely claimed by its proponents to be able to cure an assortment of conditions, including cancer and autism spectrum disorders, as well as Lim ...
, a fermented drink with claimed health benefits * Jun, a fermented drink made from green tea and honey * Kefir, a fermented dairy product *
Kvass Kvass is a fermented cereal-based Alcohol by volume, low alcoholic beverage with a slightly cloudy appearance, light-brown colour and sweet-sour taste. It may be flavoured with berries, fruits, herbs or honey. Kvass stems from the northeastern ...
, a traditional fermented drink made from bread * List of unproven or disproven cancer treatments *
Posca Posca was an Ancient Roman drink made by mixing wine vinegar and water. Bracing but less nutritious and palatable than wine, it was typically a drink for soldiers, the lower classes, and slaves. Etymology and later elaborations The word ''posca ...
, Roman vinegary drink * Tibicos, or "water kefir"


References


External links

* {{Authority control Alternative medicine Articles containing video clips Blended tea Carbonated drinks Chinese teas Fermented drinks Fermented tea Mycology Toxicology 2010s in food Manchuria