Kombucha cultures (SCOBY) are made up of yeast and bacteria, living together in a matrix of bacterial cellulose which means that the culture’s fermentation varies from location to location depending on the local organisms and conditions.
But what is in Kombucha tea when people examine it in a lab?
According to an ever-expanding base of Kombucha Research conducted around the world, there are certain identifiable acids, vitamins, and enzymes which are common between all Kombucha brews. These compounds are what make Kombucha such a powerful ally for health in addition to just being a tasty beverage.
If you’re new to the brew, it is important to gain a fundamental understanding of the byproducts of fermentation so that you can accurately, confidently augment the process and create brews that are your very own and provide the exact benefits that you are looking to reap. From flavor to fizz, each of the compounds, vitamins, and minerals listed in the subsequent sections are tiny pieces of the bigger puzzle that will allow you to ascend to Microbe Master with ease and understanding.
The “Fab Five” refers to a group of compounds commonly present in Kombucha as a result of fermentation. These compounds contribute to Kombucha’s flavor, acidity, aroma, and character, and their levels can vary significantly depending on ingredients, fermentation time, temperature, and brewing method.
Because Kombucha is a fermented food—not a standardized product—the presence and concentration of these compounds will differ from batch to batch.
What it is:
Vitamin C, also known as ascorbic acid, is a water-soluble vitamin naturally present in tea and many plant foods. It is chemically classified as an organic acid.
Biological function:
Vitamin C plays a role in collagen synthesis, antioxidant activity, and various enzymatic processes in the human body. It is considered an essential nutrient because humans cannot synthesize it internally.
Role in Kombucha:
In Kombucha, vitamin C originates primarily from the tea itself and may be altered slightly during fermentation. It contributes to overall acidity and is part of the broader profile of organic acids and antioxidants present in the finished beverage.
What it is:
Acetic acid is an organic acid produced when acetic acid bacteria oxidize alcohol created by yeast during fermentation. It is the primary acid found in vinegar.
Biological function:
Acetic acid is involved in normal metabolic pathways and is commonly consumed in fermented foods.
Role in Kombucha:
Acetic acid is a defining compound in Kombucha and is responsible for its characteristic sharp, tangy flavor. As fermentation progresses, acetic acid levels increase, shifting Kombucha from sweet to more sour. Brewers monitor acetic acid development to control flavor balance and fermentation length.
What it is:
Lactic acid is an organic acid produced by certain bacteria during fermentation. It is also naturally produced in the human body during metabolic processes.
Biological function:
Lactic acid plays a role in energy metabolism and acid–base balance in the body.
Role in Kombucha:
Not all Kombucha contains significant lactic acid, but when present, it contributes a softer, smoother acidity compared to acetic acid. Lactic acid can add complexity and roundness to Kombucha’s flavor profile, depending on the microbial composition of the culture.
What it is:
Gluconic acid is an organic acid formed when certain bacteria oxidize glucose during fermentation.
Biological function:
Gluconic acid is involved in normal metabolic pathways and is commonly used in food and fermentation applications.
Role in Kombucha:
In Kombucha, gluconic acid contributes mild acidity and is often associated with a smoother, less aggressive sourness. It typically develops later in fermentation and adds depth and balance to the overall acid profile of the brew.
What they are:
Amino acids are organic compounds that serve as the building blocks of proteins. They are naturally present in tea leaves and can also be released or transformed during fermentation.
Biological function:
Amino acids are used by the human body to build proteins, enzymes, hormones, and other essential molecules.
Role in Kombucha:
During fermentation, microbial activity can break down tea proteins into smaller components, including free amino acids. These compounds contribute to Kombucha’s flavor complexity, aroma, and mouthfeel, sometimes adding subtle savory or umami notes.
The Fab Five are not additives or guaranteed ingredients — they are naturally occurring fermentation byproducts whose presence reflects the living nature of Kombucha.
Their levels depend on:
Together, they shape Kombucha’s taste, acidity, and character, making each brew unique.
In addition to the Fab Five, Kombucha fermentation can produce or retain a variety of organic acids, vitamins, and bioactive compounds. Their presence and concentration vary depending on tea, culture, and fermentation conditions.
Malic Acid
An organic acid naturally found in fruits and fermented foods that contributes to tart flavor and plays a role in normal cellular energy metabolism.
Oxalic Acid
A naturally occurring organic acid found in many plant foods and teas that can contribute to Kombucha’s overall acid profile.
Usnic Acid
A compound produced by certain fungi and lichens that may appear in trace amounts depending on environmental and microbial factors, though its presence in Kombucha is variable and not guaranteed.
Nucleic Acids (RNA & DNA)
Naturally occurring molecules present in all living cells, including microbes, reflecting the active biological processes involved in fermentation.
Carbonic Acid
Formed when carbon dioxide dissolves in liquid, contributing to carbonation and the characteristic effervescence of fermented beverages.
Folic Acid (Vitamin B9)
A B vitamin involved in normal cell growth and DNA synthesis that may be present in small amounts due to microbial activity during fermentation.
Thiamin (Vitamin B1)
A water-soluble B vitamin involved in carbohydrate metabolism that may occur in trace amounts in fermented foods.
Riboflavin (Vitamin B2)
A B vitamin important for cellular energy production that is naturally present in tea and can persist through fermentation.
Niacin (Vitamin B3)
A B vitamin involved in metabolic pathways that may be present in small quantities depending on tea type and fermentation conditions.
Pyridoxine (Vitamin B6)
A B vitamin involved in amino acid metabolism that can occur in trace amounts in fermented beverages.
Cobalamin (Vitamin B12)
A vitamin produced by certain bacteria; its presence in Kombucha is variable and dependent on microbial composition rather than guaranteed.
Enzymes
Proteins produced by microorganisms during fermentation that facilitate chemical reactions involved in breaking down sugars, acids, and other compounds.
You might be wondering what the benefits of Kombucha might be if you can get many of these compounds from a multi-vitamin. Well… the answer might surprise you. Research has begun to demonstrate that the form that these compounds are in when they are put into pull form matter more than we originally thought. In fact, some types of vitamins are not easily accessible by your body in compressed pill form! This means that you will likely flush the majority of it out through normal excretory processes.
These compounds, as they exist in Kombucha, however, are living, biologically-active versions that your body can easily identify and process the way they were intended to be processed.
Sure, you will not be getting a therapeutic dose of them each and every time and no, Kombucha is not a great replacement for a balanced diet or supplement regimen as recommended by your healthcare professional, but it is a wonderful, tasty way to get these vitamins and minerals in a way that feels good for you body… and comes with a variety of amazing probiotic benefits!
Not only will you find that commercially available brands of Kombucha contain these wonderful compounds, you’ll be surprised to find that you can replicate this at home at a fraction of the cost. There are several benefits to brewing Kombucha tea at home but here are just a few of my favorite reasons to brew your ‘Booch at home:
Costs Less
Some of the commercially-available brands can be a bit expensive. At $3-$7 per bottle, that can be an expensive habit! Brewing your own Kombucha at home makes it so that you’re able to save on some of the costs that come with the store-bought brands while also reducing the amount of waste that comes with all of that packaging. (PENNIES per glass!)
More Control
Since you’re the brew master, you get to have more control over your recipe. You get to call the shots on any adjustments you make whether it’s with the flavor, your desired level of tartness and even the carbonation! You can change the amount or type of sugar you use and even use different types of tea to brew your sweet tea from.
It’s Fun!
Really! It’s not all work; a lot of people who brew Kombucha at home find the entire experience to be loads of fun. Of course, if you’re using the Continuous Brew Method, you streamline the whole process so it’ll feel more like an experiment and less like work.
No. Kombucha is a living, fermented food, and its composition varies from batch to batch. The presence and concentration of acids, vitamins, amino acids, and other compounds depend on factors such as tea type, sugar source, fermentation time, temperature, and the specific culture used.
No. The compounds listed on this page are naturally occurring as a result of tea composition and microbial fermentation. Kombucha is not fortified or supplemented during traditional brewing.
Kombucha can contain trace amounts of vitamins and other compounds, but levels are highly variable. It should not be viewed as a consistent or primary source of nutrients in the diet.
Fermentation transforms tea by breaking down sugars, altering organic acids, and modifying existing plant compounds. Microbial activity can also release or transform compounds already present in tea leaves.
Sourness is largely influenced by organic acid production—especially acetic and gluconic acids. Longer fermentation times and warmer temperatures typically increase acidity and reduce sweetness.
Yes. Kombucha is produced by a symbiotic culture of bacteria and yeast. However, the types and amounts of microorganisms present can vary widely depending on brewing conditions and storage.
No. Kombucha is a fermented beverage, not a standardized probiotic product. While it contains live microbes, it is not designed or regulated as a probiotic supplement.
Carbonation occurs when carbon dioxide produced during fermentation dissolves into the liquid. Bottling Kombucha for a second fermentation can increase carbonation if residual sugars are present.
Learn more about Carbonation here or head to our Complete Guide to Second Fermentation to view the process step-by-step.
Most of the compounds discussed require laboratory testing to measure accurately. Home brewers typically rely on sensory cues—taste, smell, and appearance—to assess fermentation progress.
For a deeper exploration of how Kombucha is commonly discussed in relation to wellness and consumption, you can visit our Health Benefits of Kombucha guide.
Kombucha isn’t defined by a single ingredient or compound—it’s defined by process.
What ends up in your glass is shaped by:
The Fab Five and Dynamic Dozen offer a useful framework for understanding the types of compounds commonly associated with Kombucha, but they aren’t guarantees or promises. They are reflections of fermentation in motion.
By learning what these compounds are and how they arise you gain a clearer picture of Kombucha as a living system rather than a fixed product. That understanding allows brewers to make more informed choices, adjust their process intentionally, and appreciate the natural variability that makes fermentation both challenging and rewarding.
Kombucha doesn’t ask for belief. It rewards attention.
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