Raw kombucha is made from four core ingredients: tea, sugar, water, and a living colony of bacteria and yeast known as a SCOBY. That’s it. The “raw” label means the final product is never heated or pasteurized, so the microorganisms responsible for fermentation remain alive in every bottle. What makes kombucha interesting isn’t the simplicity of its ingredients but what those ingredients become after days of fermentation.
Tea, Sugar, and Water
Every batch of kombucha starts as sweetened tea. The standard ratio most brewers use is about 7 grams of tea leaves and 70 grams of sugar per liter of water. Some brewers go heavier on the sugar (up to 80 grams per liter) or adjust the tea amount to taste, but the proportions stay in that general range. The sugar isn’t there for sweetness in the final drink. It’s food for the microorganisms that drive fermentation, and most of it gets consumed during the process.
The tea must come from the actual tea plant, not herbal blends. Black tea and green tea are the two most common choices, and they produce noticeably different drinks. Black tea kombucha ends up with a greater diversity of polyphenols (plant compounds with antioxidant activity), while green tea kombucha retains higher levels of catechins, a specific group of polyphenols linked to antibacterial and antiproliferative properties. The choice of tea, in other words, shapes not just the flavor but the biological profile of the finished kombucha.
White sugar (plain cane sugar) is the standard. The SCOBY breaks it down efficiently, and it doesn’t introduce competing flavors. Some brewers experiment with other sweeteners, but cane sugar remains the baseline for reliable fermentation.
The SCOBY: A Living Ingredient
The ingredient that separates kombucha from sweet tea is the SCOBY, short for symbiotic culture of bacteria and yeast. It looks like a rubbery, translucent disc that floats on the surface of the liquid. That disc is actually a mat of cellulose produced by the bacteria themselves, and it houses a complex ecosystem of dozens of microbial species working together.
The bacterial side is dominated by acetic acid bacteria. The most prominent genus is Komagataeibacter, which produces both the cellulose structure of the SCOBY and several of the key acids in the finished drink. Other important bacterial groups include Acetobacter, Gluconobacter, and various lactic acid bacteria like Lactobacillus. On the yeast side, the community typically includes species from groups like Saccharomyces (the same genus used in bread and beer), Zygosaccharomyces, Brettanomyces, and Pichia. The exact makeup varies from one SCOBY to another depending on its history, environment, and what it’s been fed.
No two SCOBYs are identical, which is part of why homemade kombucha batches taste different from one brewer to the next. The microbial diversity also means that kombucha isn’t a single standardized product the way pasteurized beverages are.
What Fermentation Creates
Once the SCOBY is added to the sweetened tea, fermentation begins. The yeasts break sugar down into ethanol (alcohol) and carbon dioxide. The bacteria then convert that ethanol into organic acids, primarily acetic acid, which gives kombucha its signature tart, vinegary bite. This is the same acid found in vinegar, just at lower concentrations.
Beyond acetic acid, fermentation produces gluconic acid (which contributes to the drink’s overall flavor complexity) and glucuronic acid, a compound the body uses in its natural detoxification pathways. Smaller amounts of lactic, malic, citric, tartaric, and succinic acids also form during the process. The result is a layered sourness that’s more nuanced than simple vinegar.
Fermentation also generates water-soluble B vitamins, including B1, B2, B3, B6, B12, and vitamin C, along with trace amounts of vitamin E, amino acids, and enzymes. These exist in modest quantities. Kombucha is not a replacement for a multivitamin, but these compounds do contribute to the drink’s nutritional profile in ways that plain tea does not.
How Carbonation Happens Naturally
Raw kombucha gets its fizz without any CO2 injection. The carbonation comes from a two-stage fermentation process. During the first fermentation, the SCOBY works in an open or loosely covered vessel for roughly 7 to 14 days. This stage produces the acids, some carbonation, and the base flavor.
The second fermentation is where the bubbles really develop. The kombucha is transferred into airtight bottles, often with a small amount of added sugar or flavoring ingredients like fruit juice or ginger. In this sealed, oxygen-free environment, the remaining yeast continues converting sugar into CO2, but now the gas has nowhere to escape. It dissolves into the liquid, creating natural carbonation. Ginger and mint are particularly effective at boosting carbonation levels during this stage. This is the same principle behind naturally carbonated beer and champagne.
What “Raw” Actually Means
The word “raw” on a kombucha label means the drink was never pasteurized. Pasteurization involves heating a liquid to around 180°F (82°C) for at least 30 seconds to kill bacteria. That process eliminates harmful microorganisms, but it also destroys the beneficial ones. A pasteurized kombucha is shelf-stable and safe, but it no longer contains live cultures.
Raw kombucha skips that step entirely. The living bacteria and yeast remain active in the bottle, which is why raw kombucha must be refrigerated. Cold temperatures slow fermentation to a near halt, keeping the flavor, carbonation, and alcohol content relatively stable. Left at room temperature, fermentation continues, and the drink becomes more sour, more fizzy, and potentially higher in alcohol.
Some commercial brands use chemical preservatives like sodium benzoate or potassium sorbate instead of heat to stop fermentation while keeping cultures intact. This allows for a longer shelf life without full pasteurization, though purists argue it changes the character of the drink.
The Alcohol Question
Because yeast converts sugar into ethanol, every kombucha contains some alcohol. For a product to be sold as a non-alcoholic beverage in the United States, it must stay below 0.5% alcohol by volume at all times, during production, at bottling, and afterward. If the kombucha reaches 0.5% ABV at any point in its life cycle, it falls under federal alcohol regulations and must carry a health warning label.
This threshold matters for raw kombucha specifically because the live cultures can keep fermenting after bottling. A bottle that measured 0.4% ABV at the factory could creep above 0.5% if it sits unrefrigerated for too long. Commercial raw kombucha brands manage this through careful sugar control, short fermentation windows, and cold chain logistics. Homebrewed kombucha, with less precise controls, can easily exceed 0.5% and sometimes reaches 2 to 3% ABV depending on how long it ferments and how much sugar is available.