Kombucha is a fermented beverage produced by brewing sweetened black or green tea and inoculating it with a SCOBY — a Symbiotic Culture Of Bacteria and Yeast. The SCOBY colony consumes most of the added sugar through a two-stage fermentation: yeast converts sugars to alcohol and CO₂, then acetic acid bacteria (primarily Acetobacter and Gluconobacter species) convert the ethanol to organic acids — primarily acetic and gluconic acids — producing the beverage’s characteristic vinegar-tart flavour and natural light carbonation. The result is a slightly effervescent, acidic, subtly sweet drink with trace alcohol (typically 0.5–3% ABV, though commercial versions sold without alcohol licensing are kept below 0.5%). Historically consumed in East Asia and Eastern Europe for reputed health properties, kombucha exploded into a global commercial category in the 2000s–2010s and is now a mainstream health-oriented beverage widely available in supermarkets worldwide.

In-Depth Explanation

The SCOBY — what it is:

The SCOBY (sometimes called the “mother” or “mushroom” — hence old names like “tea mushroom” and “kombucha mushroom”) is a biofilm — a cellulose matrix produced by the bacteria — that houses a stable community of microorganisms. It forms a rubbery, disk-shaped mat floating on the surface of the fermentation vessel. The SCOBY is both the fermentation agent and its own product: as each batch ferments, a new “daughter” SCOBY layer forms on top, which can be peeled off and used to start new batches or shared.

The key microbial populations in a typical kombucha SCOBY:

• Yeasts: Zygosaccharomyces bailii, Brettanomyces species, Saccharomyces cerevisiae and others — converting sugars to alcohol and CO₂
• Acetic acid bacteria: Acetobacter xylinum (now Komagataeibacter xylinus), Gluconobacter spp. — converting alcohol to organic acids, producing the cellulose matrix
• Lactic acid bacteria: Some strains present, contributing lactic acid

Fermentation process:

1. Brew strong sweet tea (black or green); allow to cool
2. Add “starter” liquid from a previous batch (acidifying the environment to prevent contamination)
3. Add SCOBY
4. Ferment at room temperature (20–28°C) for 7–30 days depending on desired tartness
5. First ferment (F1): Produces base kombucha
6. Second ferment (F2, optional): Bottle with added fruit, juice, or flavourings; seal to trap CO₂ for more carbonation; 1–3 days additional ferment

Flavour variables:

• Tea base (black produces more tannin; green produces lighter flavour)
• Sugar type (refined white, raw cane, honey — jun kombucha traditionally uses honey with green tea)
• Fermentation temperature and duration
• Added flavourings (ginger, berries, citrus, herbs)

Jun kombucha:

Jun is a variant brewed with green tea and honey rather than black tea and white sugar. The SCOBY cultures are adapted to honey’s different sugar profile. Jun is sometimes marketed as a premium variant with a gentler, more floral flavour profile than standard kombucha.

Claimed health benefits and the evidence:

Kombucha health claims are widespread in commercial marketing:

• Probiotic qualities: Kombucha does contain live bacteria and yeast, but evidence that these survive GI transit and confer probiotic effects in humans is very limited — far less robust than the evidence for well-studied probiotic strains in yoghurt or clinical supplements
• Antioxidants: From the tea base; present but diluted by fermentation
• Glucuronic acid: Often cited for “detox” claims; the body produces this independently and dietary intake via kombucha is not evidence-based for detoxification
• Organic acids: Present and likely contribute to the beverage’s mild digestive effects in some consumers

Regulatory bodies in multiple countries have recommended caution with very high kombucha consumption and noted contamination risks with home brewing (especially the risk of Aspergillus mould growth in improperly managed cultures).

History

Kombucha is believed to have originated in northeastern China (Manchuria) around 220 BCE — a claim in widespread circulation — though documented historical evidence for this specific date is thin. More reliable historical documentation comes from Russia and Eastern Europe in the late 19th–early 20th century, where kvas gribnoj (“mushroom kvass”) or tea mushroom was popular as a folk remedy. The drink spread through Germany and Western Europe in the early 20th century and gained countercultural popularity in the US and Western Europe in the 1990s wellness movement. The commercial kombucha industry grew dramatically in the 2000s–2010s — GT’s Kombucha (US), the first major commercial brand, helped define the mainstream category.

Common Misconceptions

“Kombucha is a powerful probiotic like yoghurt.” While kombucha contains live microorganisms, the scientific evidence for its probiotic health effects in humans is not equivalent to the well-studied evidence base for specific probiotic strains in clinical contexts.

“Kombucha has no alcohol.” Commercial kombucha is kept below 0.5% ABV (the legal threshold for “non-alcoholic” in most markets). Home-brewed kombucha can exceed this — sometimes reaching 2–3% ABV depending on fermentation conditions — making it potentially relevant for those avoiding alcohol entirely.

“The SCOBY is a mushroom.” The “tea mushroom” name is a folk term for what is actually a bacterial cellulose biofilm hosting yeast and bacteria — no relationship to mushroom fungi.

Related Terms

• Fermented Tea
• Camellia Sinensis
• Lacto-Fermentation
• Tepache

See Also

• Sakubo – Learn Japanese

Research

• Jayabalan, R. et al. (2014). A review on kombucha tea — microbiology, composition, fermentation, beneficial effects, toxicity, and tea fungus. Comprehensive Reviews in Food Science and Food Safety, 13(4), 538–550.

[The most comprehensive peer-reviewed review of kombucha’s microbiology, chemistry, fermentation dynamics, claimed benefits, and safety considerations.]

• Nummer, B.A. (2013). Kombucha brewing under the food and drug administration model food code: Risk analysis and processing guidance. Journal of Environmental Health, 75(8), 8–11.

[Evaluates kombucha under US food safety frameworks, identifying contamination risks in home fermentation and implications for commercial production.]

Last updated: 2026-04