Kombucha SCOBY
Nom scientifique: Symbiotic Culture Of Bacteria and Yeast — a mixed community including Komagataeibacter xylinus (cellulose mat producer), Acetobacter, Saccharomyces cerevisiae, Brettanomyces, Zygosaccharomyces, and lactic acid bacteria
Le SCOBY du kombucha — un tapis de cellulose stratifié hébergeant bactéries et levures en symbiose; convertit le thé sucré en boisson kombucha acidulée et légèrement effervescente en 7 à 14 jours
Le texte principal de cette page est disponible uniquement en anglais dans la v1. L'interface et les métadonnées sont traduites en français. La traduction éditoriale est prévue pour la v2.
À propos de cette culture
The kombucha SCOBY (Symbiotic Culture Of Bacteria and Yeast) is one of the most visible mixed cultures in modern fermentation. The 'pellicle' — the leathery, semi-translucent disc that floats on a kombucha batch — is actually a layered nanocellulose mat produced by Komagataeibacter xylinus (formerly classified as Acetobacter xylinum), an acetic acid bacterium that secretes cellulose fibrils as a survival strategy. The cellulose mat is the structural scaffold; the active microbial community lives within and underneath it, suspended in the sweetened tea below.
The core community includes: - *Cellulose producers: Komagataeibacter xylinus (the mat former), other Komagataeibacter* species - *Acetic acid bacteria: Acetobacter aceti, A. pasteurianus* — convert ethanol to acetic acid - *Yeasts: Saccharomyces cerevisiae, Brettanomyces bruxellensis, Zygosaccharomyces bailii, Pichia, Candida* — convert sugars to ethanol and CO₂ - *Lactic acid bacteria: Lactobacillus spp., Gluconobacter* — produce lactic acid and gluconic acid in smaller amounts
The community functions as a cascade. Yeasts ferment the sugar (sucrose) in the sweetened tea to ethanol and CO₂. Komagataeibacter and Acetobacter then oxidize the ethanol to acetic acid. The LAB contribute small amounts of lactic acid. The result is a drink with mild acetic-acid sourness, slight ethanol (typically 0.3-1.5%), mild lactic-acid tang, and effervescence from continued CO₂ production after bottling.
Kombucha's origin tradition is contested. Multiple regions claim continuous traditions — Manchuria/Russia (mid-19th century records), Japan and Korea (with the Japanese name 紅茶キノコ literally 'red tea mushroom'), and possibly older Central Asian traditions. The drink reached the United States and Europe in the early 20th century, surged in popularity in the 1990s as a folk-medicine fad, and exploded into mainstream commercial culture in the 2010s. The probiotic claims are real for live-culture kombucha but variable by product; pasteurized commercial kombuchas retain the flavor but lack the live cultures.
For home brewers: a kombucha SCOBY can be obtained from a previous batch (the mother), purchased from suppliers (Cultures for Health, Fermentaholics, Kombucha Kamp), or grown from a bottle of unflavored, unpasteurized kombucha. The drink is among the most accessible home ferments — sweetened black tea (7% sugar, roughly), inoculated with 10-15% starter from a previous batch plus a SCOBY, fermented at 18-26°C for 7-14 days, then optionally bottled with added sugar for secondary fermentation and natural carbonation. The technique is forgiving but cleanliness matters: mold contamination on the SCOBY or batch (visible fuzzy spots, typically white-blue-green) means the entire batch should be discarded.
*Jun* is the kombucha relative made with honey and green tea instead of black tea and cane sugar. The jun SCOBY is functionally similar to kombucha SCOBY but adapted to the honey-and-green-tea substrate; the two are not interchangeable without significant adjustment.
Classification microbienne
Conditions optimales
Ferments utilisant cette culture
Travailler avec cette culture
- Use 10-15% starter from a previous batch alongside the SCOBY — provides acidic protection against mold contamination during the early-fermentation phase.
- Use 6-7% sugar in the sweet tea — within the SCOBY community's optimal range; too little starves the yeasts, too much slows fermentation.
- Cover with breathable cloth and rubber band — needs oxygen for acetic acid bacteria; sealed containers fail.
- Taste daily after day 5 — the harvest point is subjective; harvest earlier for sweeter, later for more sour.
- For carbonation, bottle with 5-10g sugar per 500mL and seal 2-4 days at room temperature before refrigerating — produces natural effervescence.
Erreurs courantes
- Sealing primary fermentation — the SCOBY needs oxygen exchange; sealed batches produce off-flavors and weak SCOBYs.
- Adding fruit or flavorings during primary fermentation — slows the SCOBY and risks contamination. Add flavorings during secondary bottle fermentation.
- Using honey or maple syrup for kombucha (without adjusting) — kombucha is calibrated for cane sugar; honey is for jun; substituting without considering the SCOBY adaptation produces poor results.
- Throwing out 'extra' SCOBY layers — the new layer that grows during each batch can be saved, gifted, or eaten (kombucha SCOBYs are edible if not particularly tasty).
- Confusing the natural sediment and yeast strings hanging from the SCOBY with mold — strings and sediment are normal and beneficial; mold is fuzzy and colored, and means the batch should be discarded.