Kombucha has gone from health food store novelty to mainstream cooler staple in a short span of years. At Mike's on Mission Street, we carry it in bottles, cans, and keg format — and questions about what's actually in the bottle come up regularly. Here's a straightforward breakdown.
What Is Kombucha?
Kombucha is fermented tea. It starts as plain sweetened black or green tea, which is then inoculated with a living culture called a SCOBY. Over one to four weeks, the SCOBY transforms the tea into something fizzy, tart, and notably different from the sweet liquid it began as. The result is lightly carbonated, lower in sugar than the original sweet tea, and very low in alcohol — a drink with a complex flavor profile that most people take a few sips to calibrate to.
What Is a SCOBY?
SCOBY stands for Symbiotic Culture of Bacteria and Yeast. It's a living colony — typically appearing as a rubbery, opaque disc floating at the surface of the brew — made up of lactic acid bacteria, acetic acid bacteria, and various yeasts all working in concert.
Here's what actually happens: the yeasts in the SCOBY break down the tea's sugars into alcohol and carbon dioxide. The bacteria then convert much of that alcohol into organic acids — primarily acetic acid (the same acid found in vinegar) and gluconic acid. Those acids give kombucha its signature tang. The SCOBY grows with each batch; experienced brewers often maintain multiple generations of the same culture over years.
Two Fermentations, One Bottle
Commercial kombucha is typically made in two stages.
In the first fermentation, the SCOBY is added to cooled sweetened tea and left to ferment at room temperature for roughly one to three weeks. The longer it goes, the more sugar is consumed and the more tart the result. Brewers dial in their preferred balance between sweet and sour at this stage.
In the second fermentation, the base kombucha is bottled with added fruit, juice, ginger, or other flavorings, then sealed for a few more days. The remaining yeast consumes those added sugars, producing the carbonation that gives kombucha its fizz. This second stage is where most of the flavor variety comes from — ginger-lemon, hibiscus, mango, blueberry, and dozens of others you'll find on our shelves.
Alcohol and Caffeine: The Two Questions Everyone Asks
Alcohol: Kombucha does contain alcohol, but in very small amounts. Under U.S. law, a beverage sold as non-alcoholic must be below 0.5% ABV, and commercial kombucha is brewed and processed to stay under that threshold. Hard kombucha is a separate category, intentionally fermented to higher alcohol levels — typically in the range of beer — and is a different product entirely.
Caffeine: Since kombucha is brewed from tea, it does contain caffeine. Fermentation breaks down a portion of it, however, and an 8-ounce serving of commercial kombucha typically contains somewhere in the range of 6 to 15 milligrams. That compares to roughly 50 milligrams in plain black tea and close to 100 milligrams in a cup of black coffee. Think of it as effectively low-caffeine, not caffeine-free.
Kombucha on Tap
Draft kombucha — poured from a keg through a tap — has become a popular option for offices, restaurants, and events across the Bay Area. It keeps well under refrigeration, pours cleanly, and offers a quality non-alcoholic option alongside beer and wine at any gathering.
For an office or event, keg format also makes practical sense: no single-use bottle waste, easy to serve, and appreciated by guests who want something interesting that isn't soda. Pair it with a cold brew tap and you've covered a wide range of preferences without anyone feeling like an afterthought.
We carry kombucha in bottles and keg formats at Mike's, along with the tap equipment to serve it right. Stop by the store on Mission Street in the Excelsior, or get in touch before 9 AM for same-day delivery anywhere in San Francisco (current fees and minimums are on our delivery page).
Frequently Asked Questions
Does kombucha have alcohol in it?
Commercially bottled kombucha sold as a non-alcoholic beverage must stay below 0.5% ABV under U.S. law, so trace amounts are present but it isn't classified as an alcoholic drink. Hard kombucha is a distinct product brewed intentionally to higher alcohol content, similar to a light beer.
What does kombucha taste like?
Tart and lightly effervescent, with a mild vinegar-like edge that's balanced by whatever fruit or flavoring was added during the second fermentation. Ginger varieties have heat and bite; berry and tropical flavors are gentler. It doesn't taste quite like anything else, and most people find it takes a sip or two to calibrate to.
Can I order kombucha on tap for my office or event in the Bay Area?
Yes. Mike's carries kombucha in keg format and can help with tap setup. Browse our kombucha collection online or stop by the store on Mission Street in the Excelsior — we're happy to talk through what makes sense for your space or event.