There’s alcohol in kombucha. I’m shocked I tell you. SHOCKED!

Nathan Hague

Drinkers of Phuket kombucha are right to ask their brewer about the level of the alcohol in kombucha they make. As the Head Brewer here at KombuchaWOW!, it’s my job to make sure our Thailand kombucha brewery is making a drink that can be enjoyed by the most people. We don’t want to stop you from enjoying our kombucha if you’re Muslim for example (obviously if there was alcohol in kombucha we make, that would stop you!) Another example would be mothers asking if there’s any alcohol in kombucha we make. (Hint: Yes, children can drink kombucha providing they’re over 5 years of age!)

There’s a lot more I’m going to answer here in this article, and some of it might be a bit nerdy and science-heavy, but I’ll try can cut through the jargon or explain it the best I can. I will also give citations and sources where I can, so you can get the actual science on alcohol in kombucha rather than my thoughts and feelings.

In this article, we’ll also explore alcohol in kombucha: From its production process, through to the laws governing Thailand kombucha sales.

Quick Recap: What is Kombucha and How is it Made?

With all the information out there, I’m not going to spend much time or words on this, except to say that kombucha is a fermented tea that is made from tea, sugar and a culture called a SCOBY (Symbiotic Culture Of Bacteria and Yeast). The yeast (the Y in the SCOBY) and bacteria (the B) work together to ferment the tea and sugar, creating carbon dioxide and alcohol (ethanol). This process can take anywhere from 7 to 21 days, and the resulting kombucha is a slightly carbonated, tangy drink that is packed with antioxidants and probiotics.

See? You likely already knew that. Now with that behind us, let’s get into the good stuff..

The Alcohol Content of Kombucha

Your typical homemade kombucha will have an alcohol content is typically between 0.5% and 2.5% ABV (alcohol by volume). At the lower 0.5% ABV, this is significantly lower than most alcoholic beverages where they’re around 4.5% ABV and above. This is because the yeast and bacteria work together in the SCOBY to consume most of the alcohol in kombucha during the fermentation process. However, the exact alcohol content can vary depending on the temperature and brewing time – as well as the sugar source – as we’ll see in detail later on in the article.

The Fermentation Process In Kombucha

I talked about the the SSCOBY before, and kombucha is a result of a symbiotic fermentation process between yeast and bacteria. This means under normal fermentation conditions, the yeast consume the sugar and its byproduct is the alcohol in kombucha. We then have the bacteria consuming the this alcohol in kombucha to make a byproduct of probiotics.

That’s the basic version.

In a more science version: The yeast species involved in the process, typically a strain of Saccharomyces cerevisiae, carry out alcoholic fermentation through the conversion of sugars in the sweet tea mix, into ethanol (C2H5OH) and carbon dioxide (CO2) by the following metabolic pathway:

C6H12O6 (glucose) + yeast enzymes -> 2 C2H5OH (ethanol) + 2 CO2

This initial process of alcoholic fermentation occurs within the temperature range of 68-86°F (20-30°C), and lasts on average between 24-72 hours, depending on the specific yeast strain. During this period, the specific gravity (SG) of the kombucha tea decreases, indicating the conversion of sugar into ethanol and CO2.

It is estimated that every 1% decrease in SG roughly corresponds to a 1% increase in ABV.

The relationship between specific gravity and alcohol content is not exact, but it is roughly estimated that every 1% decrease in specific gravity corresponds to a 1% increase in alcohol by volume. This estimate is based on the fact that ethanol is less dense than water, so as the amount of ethanol in the kombucha increases, the specific gravity decreases.

It is important to note that this relationship between specific gravity and alcohol content is not linear and can vary depending on factors such as temperature, yeast strain, and sugar content – as we’ll read later in the article.

The bacterial species involved in the fermentation process is typically a strain of Acetobacter, and undergoes acetic acid fermentation by converting ethanol into acetic acid (C2H4O2) through the following metabolic pathway:

C2H5OH (ethanol) + Acetobacter bacteria -> C2H4O2 (acetic acid) + H2O (water)

This process of acetic acid fermentation also occurs within the temperature range of 68-86°F (20-30°C) and typically lasts between 24-72 hours, depending on the specific bacteria strain.

During this period, the SG of the kombucha tea continues to decrease, and the alcohol content increases as a result of the acetic acid fermentation.

According to the Journal of Agricultural and Food Chemistry, a typical kombucha fermenting for 7 days at room temperature (72°F or 22°C) will have an initial SG of 1.050 (5% ABV) and a final SG of 1.000 (0% ABV), with an average ABV of 0.5%.

In contrast, a kombucha fermenting for 14 days at the same temperature will have an initial SG of 1.050 (5% ABV) and a final SG of 0.995 (1% ABV), with an average ABV of 1.0%.

In fact, these values that lead to the alcohol in kombucha being present, can be influenced by several parameters, including:

• Temperature
• Sugar source
• Duration of fermentation

For instance, increasing the temperature during fermentation accelerates yeast activity and leads to higher ethanol production. The use of alternative sugar sources such as fructose, maltose, or sucrose, instead of glucose, can also lead to an increase in ethanol content (so there actually tends to more alcohol in kombucha batches that are commonly made by Thailand kombucha home brewers!)

These alternative sugar sources such as fructose, maltose, and sucrose have a different chemical structure, and a distinct metabolic pathway than glucose, and therefore they may be metabolised differently by yeast, leading to variations in ethanol production.

Kombucha’s Ethanol Content

The reduction of ethanol content in fermenting kombucha occurs due to the acetic acid fermentation carried out by Acetobacter bacteria. This process converts ethanol into acetic acid, thereby reducing the ethanol content of the kombucha.

Again, according to this study, the ethanol content of kombucha decreased over the course of 7 days of fermentation. This decrease in ethanol was accompanied by an increase in the acetic acid content of the kombucha, indicating the presence of acetic acid bacteria in the fermentation process.

Over a period of 21 days, the ethanol content of kombucha decreased from 1.22% to 0.32%. This decrease in ethanol was attributed to the conversion of ethanol into acetic acid by Acetobacter bacteria.

This is why when you make kombucha at home, the longer you leave it, the more sour it becomes: It’s got more acetic acid in it!

So to sum up the reason why alcohol in kombucha reduces over time, it’s a result of the acetic acid fermentation carried out by Acetobacter bacteria. Over time, the bacteria convert the ethanol into acetic acid, resulting in a decrease in the ethanol content of the kombucha.

Comparison of Ethanol Content In Other Fermented Foods

Whilst the ABV levels in other fermented drinks such as jun or kvass can similar to the alcohol in kombucha, many people are surprised to know there is naturally occurring ethanol in other common fermented foods.

Here is a table showing the top ten fermented foods, ordered from highest to lowest naturally occurring ethanol content:

Can I Use A Refractometer To Measure Alcohol In Kombucha?

A refractometer is used to measure the amount of dissolved sugar content in a liquid, by determining the refractive index of a solution. The refractive index is the ratio of the speed of light in a vacuum to its speed in a medium, such as the kombucha you’re trying to measure. In terms of content of alcohol in kombucha, the refractive index of the kombucha liquid sample changes when alcohol is present. It’s this refractive index that we then use for determining the alcohol by volume (ABV) of the kombucha by measuring the refractive index of the solution and comparing it to a chart of known values. However, it is important to note that the presence of other components in the solution, such as acetic acid in kombucha, can affect the accuracy of the reading.

A refractometer measures how light bends as it passes through a liquid into a prism in the tool’s body. The “medium” in a refractometer refers to the substance being measured, such as kombucha, which is placed on the prism surface of the refractometer to determine its sugar content based on its refractive index.

Readings from refractometers will be incorrect as acetic acid has a different refractive index, compared to the sugar and water present in the kombucha. This difference in refractive index can result in a shift in the apparent SG reading obtained from a refractometer, leading to inaccuracies. In the case of a Thailand home brewer, this will be good enough, but as a commercial Thailand kombucha brewer, these inaccuracies can push the kombucha over a legal threshold, putting the kombucha brewery into a legal issue zone.

Furthermore, the volatility of CO2 in kombucha can cause additional difficulties in obtaining accurate SG readings using a refractometer, making it necessary to use specialised hydrometers or refractometers specifically designed for measuring the SG of kombucha. CO2 bubbles form and dissipate, altering the refractive index of the kombucha sample, which makes consistent readings kind of impossible. The bubbles of CO2 can also trap air pockets, creating more inconsistent readings when measuring the SG.

How Commercial Thailand Kombucha Breweries Like KombuchaWOW Test For Alcohol

Commercial Thailand kombucha breweries measure the SG of our kombucha using specialised equipment to test the alcohol in kombucha levels such as Anton Paar’s Packaged Beverage Analyzer. (PBA) We can use this to test our own alcohol levels in our batches without waiting for commercial food testing labs which can can take up to 2 weeks to return samples findings!

That said, we always send random samples from random batches away for testing by independent food testing labs, as a baseline for our own alcohol in kombucha testing processes!

Equipment such as the PBA obviously gives a magnitude higher in accuracy than using the basic refractometer, but it’s not as good as using gas chromatography method!

The most accurate testing of kombucha ABV in food testing labs, is from their use of a gas chromatograph. These machines such as the 8890 GC System by Agilent Technologies, are equipped with flame ionisation detection and provides high accuracy and precision for alcohol analysis in beverages. This equipment is priced around $70,000 depending on configurations and options!

Gas chromatography is considered the gold standard of testing alcohol in kombucha levels.

Obviously, both of these specialised instruments are typically only available in professional food testing laboratories, or specialised equipment sales channels, and may not be accessible or feasible for individual home brewers or small scale kombucha producers.

Using a standard refractometer, you can at least do a basic test for the alcohol in kombucha batches you make at home – even if you now know why they’re not perfect.

How To Remove The Alcohol In Kombucha

The process of removing alcohol in kombucha commercially can be achieved through two main methods.

1. Kombucha Pasteurisation

One common method is to pasteurise the kombucha to kill the yeast, which will stop the fermentation process: No further fermentation is possible, so no additional alcohol content. This does assume there is <0.5% ABV in the kombucha to start with before pasteurisation.

This can be done by heating the kombucha to a temperature of around 70-80°C for a period of several minutes, which will kill the yeast without affecting the flavour or nutritional content of the kombucha. However, this will also kill all the beneficial probiotics and beneficial bacteria in the kombucha, rending it a different sort of functional drink rather than one you are buying and drinking for a healthy gut.

Most commercial kombucha brands are required to pasteurise their kombucha for legal and regulatory compliance. Some put the probiotics and bacteria back into the drink post-pasteurisation to make it the health claims on the labels, but most don’t.

2. Vacuum Distillation Process

Another method for removing alcohol from kombucha commercially is to use a vacuum distillation process. This process involves applying a vacuum to the kombucha, which lowers the boiling point of the alcohol, causing it to evaporate at a lower temperature than water. The vaporised alcohol can then be collected and condensed back into a liquid form. This method is more efficient than pasteurisation, but can also be more expensive and requires specialised equipment and knowledge that is most-definitely out of reach of most Thailand kombucha breweries.

It’s also very cool to think that recovered alcohol in kombucha from this process, could be used to power the brewery! Slightly modified generators could run on this recovered ethanol when the electricity goes out at our Phuket kombucha brewery (which happens from time to time!). This would be in line with our sustainability aims here at KombuchaWOW! as well.

Is Kombucha Regulated as an Alcoholic Beverage?

The regulation of kombucha and its ethanol content varies globally, but it is especially relevant in the United States and Thailand. In the United States, the Food and Drug Administration (FDA) regulates kombucha as a non-alcoholic beverage. The FDA requires that kombucha contain no more than 0.5% alcohol by volume (ABV), which is lower than the typical alcohol content of beer or wine. However, in 2010, the FDA conducted a crackdown on kombucha manufacturers and pulled all kombucha products off shelves nationwide due to concerns about high levels of alcohol in certain brands of kombucha. This event, referred to as the “kombucha apocalypse,” was a result of a few kombucha brands having alcohol levels that exceeded the legal limit, raising concerns about the safety of the beverage.

In Thailand, the regulation of kombucha is more relaxed. There is no specific regulation regarding the production and sale of kombucha, but the government requires that all food and beverage products contain no more than 1.5% alcohol. Despite this, kombucha Phuket breweries like us here at KombuchaWOW! make sure our batches of kombucha never go past the United States’ limit of 0.5% ABV. KombuchaWOW! lab tests in the way you read about in the previous section through 2 different food labs.

It is important for you as a Consumer, to know the alcohol in kombucha level before you drink it, and our Phuket kombucha brewery goes to great length to help you make informed decisions about our products you purchase and consume from us. It’s of my personal opinion that all commercial Thailand kombucha breweries should be doing the same as us, so Consumers know is kombucha safe for kids to drink or not, from the labelling. If we all adhere to the United States 0.5% rule instead of Thailand’s 1.5% rule, then we can confidently say our kombucha is safe for children to drink, along with kombucha is ok for recovering alcoholics and other higher risk drinker categories.

Article Conclusion

Alcohol in kombucha is the number one question we get asked a Phuket kombucha brewery. I hope in this article I have answered the main questions you may have, which is to say yes there is always alcohol in homemade kombucha due to the presence of yeast and sugar as part of the fermentation process. We’ve also covered how Thailand brewing laws mean commercial kombucha brewers like us, should be brewing to no more than 0.5% ABV. I have also explored the ways of testing for kombucha in alcohol if you’re a home brewer using standard refractometers – and the reasons for why they’re good but not accurate if you want to sell your kombucha to others. Finally, I’ve given you two main ways we can remove alcohol in kombucha through pasteurisation and the more expensive vacuum distillation process.

If you learned something today in reading this, please share the article in your kombucha groups! I certainly don’t know everything about alcohol in kombucha, and the science is changing monthly – so anything you can add or update me on, please do!

Booch on!