How To Make Kombucha: The Comprehensive Post
by Susan Grey on January 03, 2020
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What Is Kombucha?
Kombucha is a lightly effervescent drink that’s prepared via the fermentation of freshly brewed and sweetened tea. This results in a slightly alcoholic sweet brew with a hint of tartness due to its acidic nature.
Kombucha’s popularity has been known for over 2000 years in Asia, where the brew is believed to have originated. With its low-calorie count and billions of active probiotic culture, the drink has gained quite a following among health-conscious home-brewers.
How Is Kombucha Obtained?
Kombucha starts as freshly brewed tea, which is sweetened, the culture feeds on the sugar during fermentation. The process requires aerobic respiration to provide oxygen to the culture.
When yeast culture breakdown the dissolved sugar, it produces alcohol as a byproduct. The alcohol gets broken down further by the alcohol fixing bacteria culture, thus releasing acetic acid, which gives kombucha its acidic nature.
Another byproduct of the process is carbon dioxide, which is released by the culture. Since it's produced in small quantities, the majority of the gas dissolves in the brew, making it effervescent. Meanwhile, the excess carbon dioxide is allowed to escape freely as the fermentation jar isn’t sealed airtight.
Considerations Before Making Kombucha
Kombucha requires sugar to ferment properly. This raises the concern in terms of just how much of the sugar remains after fermentation. It's important to note that the culture feeds on most of the dissolved sugar during the first fermentation leaving behind less than 1/10 of the initial sugar content.
Extending the brew time will also further reduce the amount of sugar in the drink as the culture will feed on it over time. This can, however, result in a sour brew, which might be too strong to drink without diluting.
Check out our article Kombucha and Sugar for more information.
Kombucha relies on tea leaves to not only flavor it but also provide the nutrients that the culture feeds on other than the sugar. Most teas, however, have caffeine. On the one hand, it significantly improves concentration and energy levels, but on the other hand, it's quite addictive, and overconsumption of caffeine can lead to insomnia.
If you are sensitive to caffeine, you can consider using low and caffeine-free alternatives such as decaf and rooibos tea. The resulting drink will still have a great flavor but without the caffeine content.
Just like other fermented drinks, kombucha is a rich source of live bacteria and yeast probiotics. These ‘good’ bacteria help in restoring the balance within the gut bio and also help in protecting the body against harmful bacteria.
Because probiotics are essentially live bacteria cells, the consumption of such a drink is prohibited when it comes to weakened immune systems. People with weakened immune systems include pregnant women, chemotherapy patients, AIDS patients, and anyone who might be on immunosuppressants.
Why Homebrew Kombucha?
A cheap source of probiotics
Home-brewed kombucha provides a probiotics rich brew at a low cost. All you need to purchase to get the brew started is sugar, tea, water, and a symbiotic culture of bacteria and yeast (SCOBY) and starter tea from a previous batch.
Homebrewing is much more affordable, unlike buying bottled kombucha. This is because all required raw materials are locally available and can be bought in bulk, making it even more economical to home brew.
Ability to add your specific flavors
With a continuous supply of kombucha from a homebrew setup, you can experiment with various flavors in order to find the right blend of taste and aroma that best fits your needs. This is done during the second ferment.
Kombucha on demand
Avid kombucha homebrewers will tell you that a continuous brewing setup is one of the best investments you can make. The setup ensures you have a continuous supply of kombucha with the capability of harvesting up to 25% of the overall capacity every 72 hours.
No additional preservatives
Home-brewed kombucha contains no added preservatives as it’s naturally long-lasting. After harvesting your raw kombucha, you can keep it bottled in the fridge for up to 3 months while still retaining its probiotic benefits. However, the flavor might take a beating, making it quite vinegary.
Raw kombucha has a natural probiotics balance
Raw kombucha contains a naturally balanced and symbiotic collection of yeast and bacteria culture. This natural balance is essential as, without it, one species can easily overgrow, leading to eventual rot and mold growth. Homemade kombucha is also much healthier compared to pasteurized kombucha, which has a custom added culture after the heat treatment phase.
Origins and History of Kombucha
Kombucha is said to have been first brewed in Manchuria, a region best described as modern-day northeast Asia. The drink then spread to traditional Russia and Eastern Europe during the silk road trade age.
Archeological evidence points to both preservation fermentation and alcoholic fermentation as far back as 221BCE during the Qin Dynasty in modern-day China. However, since kombucha is, in fact, more of a Japanese name, then there’s no telling exactly where the brew started, but its origins can be traced back to ancient Asia.
Types Of Kombucha
Over the years, brewers have identified common recipes that can be used to transform raw kombucha from just an ordinary effervescent drink into a golden elixir. These rely on either a second fermentation set up or by tweaking the original recipe and the fermentation conditions to achieve the desired flavor.
Raw kombucha is required to make a fruity kombucha. Once the brew is fully fermented, it's transferred into bottles, and the crushed fruits of choice are added. The bottle is then sealed airtight to force the culture to ferment the kombucha in the absence of oxygen anaerobically. The carbon dioxide produced gets dissolved in the brew, making it fizzier.
Some of the best fruits to flavor kombucha include blueberries, ginger, strawberries, cherries, apples, lemons, and pineapple. The fruits are often blended with a spice to give the final drink a complex taste profile; these include cinnamon, basil, and almond extract. The second ferment is quite short, normally taking up to 3 days, after which the bottles should be stored in the fridge. Here the low temperatures will slow down the carbon dioxide production, thus easing down on the pressure, which can often result in bottles exploding.
To reduce the amount of sugar left in the kombucha after fermentation, it's recommended to stick to 1/4 cup (50g) of sugar for every 4.2 cups (1 liter) of freshly brewed tea. This ensures that only about 1% sugar concentration remains in the final drink.
It's important to note that flavored kombucha often contains added sugar, making it less healthy compared to raw.
Non-alcoholic kombucha contains 0% alcohol. While the initial brew does contain natural amounts of alcohol (around 0.5-1%), the alcohol can be evaporated by pasteurizing the drink. This leaves the drink alcohol free but also probiotics free. Pasteurized kombucha, therefore, doesn’t contain any health benefits.
Is it possible to obtain raw and alcohol free kombucha?
It’s impossible to have raw kombucha that's completely alcohol free as the yeast culture is constantly producing ethanol as it breaks down the dissolved sugar in the brew.
When left to ferment with a yeast culture as the majority instead of a symbiotic balance between bacteria and yeast cells, kombucha will often have an alcohol content of up to 6% ABV. As a result, hard kombucha is often categorized as an alcoholic beverage.
Jun kombucha is fundamentally different in that it relies on raw honey as a source of sugar and green tea for the culture to feed on. Jun tea is more distinctive due to its green color, while kombucha is brown-black, depending on the tea leaves used to brew. Jun kombucha requires specially adapted Jun SCOBY, which can interact with raw honey, which also contains its own bacteria culture without any adverse effects. Instead, the culture will ferment the drink just like it usually would. It’s important to note that raw honey contains a natural bacteria culture that can harm the kombucha SCOBY culture; hence it cannot be used.
Check out our full article on Jun Kombucha here.
Kombucha wine is a much stronger form of your ordinary kombucha thanks to the increased alcohol content (6%) and requires wine yeast to especially breakdown the sugar into ethanol. Just like raw kombucha, kombucha wine requires an aerobic first ferment. After this, the drink undergoes a second ferment whereby a fruity flavor gets infused into the fresh brew.
The second ferment takes place under anaerobic conditions whereby the lack of oxygen supply prevents the bacteria culture from breaking down the ethanol released by the yeast into acetic acid. This ensures that the drink contains above than average alcohol content, and it also lacks the vinegary flavor commonly associated with long fermentation stages.
Types Of Brewing Setups
A continuous brewing setup makes it possible to harvest raw kombucha regularly without having to dismantle the entire set up after one batch. Since all you need to do is refill the brew with a similar volume of freshly brewed and sweet tea.
The setup consists of a considerably large fermentation vessel, usually up to 5 gallons. The setup is first filled with freshly brewed and sweet tea, which has been mixed with the starter tea, and then a SCOBY is added. The initial fermentation may take much longer up to 14 to 21 days as the culture has to work on the entire volume.
After the first brew is ready, you can harvest up to 25% of the volume and top off the setup with a similar amount of freshly brewed sweetened tea. During its optimal production, a continuous brewing setup can ferment kombucha quickly, allowing for harvesting every three days. This provides freshly fermented kombucha on tap. We recommend this method if you are a regular drinker.
We have a full article on Continuous Brewing, if you're interested in learning more.
Single batch brewing
Single batch brewing setup refers to a one batch at a time kombucha fermentation. Unlike continuous brewing, a single batch brewing set up will require you to take it apart after every batch for cleanup and setting up a new batch. Single batch brewing is normally done in glass jars typically 1 gallon or less.
A single batch brewing setup only requires a vessel, cloth cover, or filter paper and a rubber band to hold it in place. As for the ingredients, you will require freshly brewed and sweet tea, starter tea, and a SCOBY. The set up takes typically around 7 to 14 days to ferment.
Commercial brewing relies on high production fermentation setups, which can be used to brew vast amounts of kombucha for a commercial entity. Unlike home brewing, which doesn’t have to follow any production guidelines, the commercial brewery is subject to the law. It has to undergo strict fermentation timelines and to maintain high standards of hygiene and quality as their products have to meet the requirements set by the FDA.
Alcohol and Kombucha
The alcohol content in kombucha is as a result of the aerobic breakdown of the dissolved sugar by yeast cells to form ethanol. Under normal circumstances, most of the ethanol gets broken down by the bacteria culture into acetic acid, under the presence of oxygen.
What is the alcohol content in kombucha?
Raw homemade kombucha contains around 0.5 to 1.5% alcoholic content. Hard kombucha, on the other hand, contains up to 6% alcoholic content.
What affects the alcohol content?
Yeast and bacteria culture
The amount of alcohol in the final kombucha brew will be heavily influenced by the bacteria and yeast culture in the drink. If the brew contains a majority yeast culture, there will be more alcohol content in the brew as more sugar will be broken down into ethanol.
On the other hand, if the brew contains a majority of bacteria culture, then the alcohol content will be lower. This is because the bacteria culture feeds on the ethanol and oxidizes the ethanol to form acetic acid.
The higher the amount of sugar dissolved in the brew, the higher the amount of ethanol produced during the fermentation stage. If you end up with low alcohol content, you can add sugar during the second ferment. The bottle is then sealed to keep off oxygen, thus forcing the yeast the metabolize the sugar anaerobically. This leads to increased alcohol content as the bacteria culture cannot oxidize the ethanol in the absence of oxygen.
Temperature influences the enzymes responsible for controlling the metabolism of yeast cells. Thus, maintaining a constant optimal room temperature will result in increased alcohol production. Lowering the temperature will result in reduced alcohol production while increasing the temperature will denature the yeast culture leading to reduced alcohol production.
The amount of oxygen available during the second ferment will heavily influence the amount of alcohol in the final brew. This is because the bacteria culture will require oxygen to oxidize the alcohol into acetic acid. Thus, having an airtight seal in your second ferment setup not only keeps in the carbon dioxide for added fizziness but also keeps out oxygen, thus reducing the amount of acetic acid produced while retaining high alcohol content.
How to lower or increase alcohol content in kombucha
Increase the amount of bacteria culture
Increasing the amount of bacteria culture in the brew results in increased alcohol breakdown. This leads to reduced alcohol content in the final brew.
Increased oxygen supply makes it much easier for the bacteria culture to breakdown alcohol into acetic acid and carbon dioxide. This can be done by leaving the fermenting jar unsealed during the last days before the end of the fermentation period.
Using less sugar during the second ferment results in reduced alcohol content. Alternatively, you can adjust the recipe used to brew the fresh tea and use the minimum amount of sugar required to further drive down the amount of alcohol in the final brew.
Reduce the bacteria culture
Reducing the bacteria culture in the brew results in reduced ethanol breakdown. This can be achieved by using a culture with a majority of yeast cells or simply adding more yeast cells. The increased yeast population also results in increased sugar breakdown into ethanol which leads in increased alcoholic content.
Reduce the supply of oxygen
In order for the bacteria cells to metabolize ethanol they require oxygen. Thus reducing the oxygen supply by sealing the fermentation jar results in reduced ethanol breakdown.
Increase sugar content in the brew
Adding more sugar to the ferment results in increased ethanol production. As the yeast culture breaks down the extra sugar.
For further questions about the alcoholic content of kombucha, check out our articles Do You Have To Be 21 To Buy Kombucha?
How Much Time Does It Take To Brew Kombucha?
Generally, homemade kombucha takes anywhere from 7 to 14 days to ferment fully. After this, the drink can be put through a second ferment, albeit much shorter as it takes only 3 to 5 days to infuse the flavors in the second ferment fully.
Effect Of Time On Kombucha
The effect of time on kombucha mainly encompasses the changes in flavors as time goes on and other chemical changes that take place over time. These include:
Increase in alcohol content
As kombucha ferments, for an extended time, the culture feeds on most of the sugar dissolved in the brew and converts it to ethanol.
As kombucha ages with each additional day, it gains a more acidic flavor, which blends perfectly with the sweetness of the remaining dissolved sugar for the ultimate rich flavor.
Decreased sugar level
The yeast culture will feed on the dissolved sugar in the kombucha and will steadily reduce the amount of sugar in the brew over time.
Increase in acetic acid
If not sealed airtight, the ethanol produced by the yeast culture gets broken down by the bacteria culture into acetic acid and carbon dioxide. This process requires oxygen and can, therefore, be slowed by sealing the bottle.
As the culture feeds on the dissolved sugar, it also feeds on some of the caffeine and polyphenols originally from the tea leaves. As this continues, the brew will lose its caffeine content over time.
Where To Store Kombucha While Fermenting
To fully ferment, kombucha should be kept under consistent and optimal conditions like in the pantry.
Considerations With Where To Store Kombucha While Fermenting
Optimal temperature range
When brewing, the temperature will influence just how fast the entire brew will take to ferment. Keeping the brew within room temperature ensures that the yeast and bacteria culture operate within optimal temperature ranges allowing them to feed on the dissolved sugar at a much faster rate.
Absence of direct sunlight
Sunlight contains UV rays, which are quite harmful to the yeast and bacteria. To avoid denaturing your culture, you should consider storing the fermenting brew away from direct sunlight or any other lights which might emit UV rays.
Kombucha brewing is a rather delicate process and can easily be contaminated by germs and bacteria from nearby sources. These include drainages and other fermenting cultures which rely on a different culture for fermentation. This can be avoided by storing the fermenting kombucha away from ambient sources of bacteria and away from other fermenting projects.
Ideal Temperature Ranges For Various Ferments
80 degrees F (26.6 degrees C)
75 to 85 degrees F (23.8 to 29.4 degrees C)
72 degrees F (22.2 degrees C)
65 to 80 degrees F (18.3 to 26.6 degrees C)
70 degrees F (21.1 degrees C)
60 to 85 degrees F (15.5 to 29.4 degrees C)
72 degrees F (22.2 degrees C)
65 to 74 degrees F (18.3 to 23.3 degrees C)
75 degrees F (23.8 degrees C)
68 to 78 degrees F (20 to 25.5 degrees C)
75 degrees F (23.8 degrees C)
70 to 80 degrees F (21.1 to 26.6 degrees C)
What is a SCOBY?
A SCOBY refers to a symbiotic culture of bacteria and yeast that’s symbiotically balanced to depend on each other. A SCOBY appears as a thin gelatinous film that grows in size with each successive fermentation. Along the way, the SCOBY takes the shape of the fermenting jar. A SCOBY has a mushroom-like surface and a whitish-creamy color.
The SCOBY is used as the source of bacteria and yeast culture to ferment the freshly brewed and sweet tea into kombucha.
Where can you get SCOBYs from?
Growing one from starter tea
You can grow a baby SCOBY by fermenting freshly brewed and sweetened tea with raw kombucha (also known as starter tea) from a previous batch or the store. The kombucha acts as a starter tea as it already contains the required probiotics to get the brew going. It is also slightly acidic, thus providing the right environment for the culture while keeping off harmful bacteria.
After a while, a thin film should start forming near the top surface of the liquid. This is the baby SCOBY, and it can now be used to set up other brews or transferred to a SCOBY hotel where it can continue to grow unobstructed.
Buy online or in local health stores
Some firms exist for the sole purpose of growing and selling kombucha SCOBYs. There are two varieties typically sold; dehydrated, and those that are packed with starter tea. The dehydrated SCOBY will have to be activated before it can be used to ferment any kombucha. The ones that ship containing tea are not only ready to use after buying, but the tea can also be used as a starter for your next brew.
As kombucha gains popularity, so does the number of homebrewers increase. As a result, it’s much easier to get a SCOBY from a fellow brewer. Alternatively, you can join brewing forums and groups on