What is it about?
The term Kombucha identifies a "whole category of functional beverages based on fermented tea (green or black quality), slightly sparkling and sugary, typically oriental.
The composition of the microbial populations in the various scoby cultures is variable. More often, the prevalence of yeasts belonging to the genus is observed Saccharomyces, which carry out alcoholic fermentation, and the presence of bacteria belonging to the species Gluconacetobacter xylinus, which oxidize alcohols to acids.
The origin of the kombucha, as well as the etymology of the term, is unknown; in fact, the word was translated into the Western alphabet only in 1991, but it is conceivable that the drink has been well present in Eastern Russia since the early 1900s.
Kombuchas are traditionally produced at home or locally; only in the late 1990s did they make their appearance in America in the form of a bottled beverage.
Kombuchas are known in the Chinese language as chájūn, in Japanese as kocha-kinoko, in Korean as hongchabeoseotcha and in Russian as chaynyy grib; all these nouns have the same meaning, ie "tea mushroom".
Some believe that kombuchas are capable of helping to cure many diseases and ailments, although there is no concrete evidence to prove this.
Conversely, many cases of adverse effects related to the consumption of kombucha have been documented and, in home preparation, there is a certain risk of adverse contamination.
A systematic review revealed that the various, mostly very vague benefits of kombucha consumption do not justify the risks. Therefore, beverages should not be recommended as therapeutic foods; this does not mean that they are still included in the whole of functional beverages.
Health implications
As anticipated, the consumption of kombucha has been publicized on the belief that they can boast certain therapeutic effects, including:
- Improve various pathological conditions including AIDS, cancer and type 2 diabetes mellitus
- Stimulate the immune system
- Increase libido
- Reverse the formation of gray hair.
However, the scientific evidence on humans is considered rather unsatisfactory. Although animal and in vitro tests suggest that the consumption of kombucha may prove to be, if not therapeutic, as useful, in 2014 a (for the moment in vain) human experimentation project to confirm or refute these theories.
In a 2003 systematic review, researcher Edzard Ernst defined kombucha as an "extreme example" of an unconventional remedy, due to the large disparity between the unlikely therapeutic effects and the harmful potential of kombuchas. It was then concluded that the list of real therapeutic benefits is rather insignificant and in any case inferior to the risks deriving from it; moreover, it is possible to say with certainty that kombucha should never be recommended for medicinal use in certain diseases.
Side effects
Fortunately, reports of adverse effects related to kombucha consumption are quite rare, but still relevant. The scarcity of complaints is partly due to the rarity of the circumstances and partly to the underestimation of perceived symptoms.
Adverse effects associated with the consumption of kombucha include: liver toxicity, renal toxicity and metabolic acidosis. One woman died as a result of consuming kombucha, although it was not possible to unequivocally correlate cause and effect.
Some possible negative health effects of kombucha include: acid pH (tendency to acidosis of the blood), excess microorganisms and unwanted bacterial or fungal contamination. Regarding this last occurrence, certain studies have revealed the presence of usnic acid in kombucha, that is a "hepatotoxin typically secreted by cyanobacteria of lichens.
Topical use of kombucha has also been associated with infections with anthrax on the skin, but it is unclear whether the contamination occurred during storage or production.
Thanks to its microbial contribution and the frequent dirt of the containers, kombucha is strictly forbidden to immunosuppressed subjects, pregnant women, nurses and children under 4 years old.
As far as commercial preparations are concerned, on the other hand, it is likely to hypothesize a greater safety of use.
Chemical composition
The sucrose some kombucha is first biochemically converted into fructose And glucose, and subsequently in gluconic acid And acetic acid (well present in the drink).
Kombuchas also contain enzymes, amino acids, polyphenols and various organic acids; the exact quantities of these elements vary from case to case.
Other specific components of kombucha include ethanol, glucuronic acid, glycerol, lactic acid, usnic acid (see above) e water-soluble vitamins (group B And ascorbic acid).
The alcohol content of kombucha is generally less than 1%, but increases with fermentation time.
Biology of Kombucha
Those of kombucha are symbiotic mixed cultures of bacteria and yeasts, similar in composition and appearance (reticulum in suspension) to the "mother of the" vinegar ".
Cultures may contain one or more yeasts, such as Saccharomyces cerevisiae, Brettanomyces bruxellensis, Starry candida, Schizosaccharomyces pombe And Zygosaccharomyces bailii.
The bacterial component of kombucha also includes several species, including almost always the Gluconacetobacter xylinus (which ferments the alcohols produced by yeasts into acetic and other acids); its function in the drink is to increase acidity and limit the ethanol content.
The population of bacteria and yeasts that produce acetic acid increases especially in the first 4 days of fermentation and decreases thereafter.
The G. xylinum produces microbial cellulose and is responsible for most of the physical structure of the suspended lattice (mother).
Due to the presence of usnic acid, the mixed (presumably symbiotic) culture of kombucha has also been described as lichen; however, as of 2015, no reports have identified cyanobacteria species (typical of this living combination) in association with the fungal components of the drink.
Other Uses
The dried Kombucha “mother” takes on the consistency of a leather-like fabric. Known as microbial cellulose, it can be molded into various shapes to create seamless clothing.
Using various liquids for cultivation (such as coffee, black tea and green tea) it is possible to obtain microbial cellulose of different colors, without having to artificially dye them (this is however possible).
The various growth media and dyes also change the texture of the fabric and the perception to the touch.
Microbial cellulose is similar to vegetable cellulose and is characterized by eco-sustainability and biodegradability.
In 2011, London-based designer Suzanne Lee presented kombucha textile fiber in application to footwear and clothing. In 2014, designer Sacha Laurin debuted a clothing collection made entirely of kombucha fabric.
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