Kombucha
Kombucha is an ancient tonic that has been brewed lovingly at home for centuries or perhaps even millenia. But what the heck is it? Fermented tea! Just like chocolate is fermented cacao and sauerkraut is fermented cabbage, kombucha is the end result of microbes converting tea and sugar into an effervescent, lightly tangy, refreshing beverage loaded with nutrition in living form.
Unlike sauerkraut, whose organisms live on the leaves of the cabbage, the microbes that ferment the sweet tea live together in a pancake of bacterial cellulose (primarily Brettanomyces) called a SCOBY. An acronym for “symbiotic culture of bacteria and yeast” invented in the 1990s to distinguish the culture from the drink, it also has been called many other names throughout history including “mother,” “mushroom,” and “tea fungus” to name a few.
If you’ve consumed raw apple cider vinegar, you may have noticed a similar culture living in the bottle. Kombucha is also an acetic acid-producing ferment, hence the tangy flavor. You might even think of kombucha as “tea vinegar,” though it’s a very smooth type of vinegar, topping out between 0.25% and 1% total acids, whereas vinegar from the store is typically around 5%. The brew is harvested well before the flavor is too intense to consume as a beverage. The acetic acid bacteria produce cellulose as a byproduct which is why both ferments create a mother.
History of use & diaspora
Due to the recent explosion in the popularity of kombucha, many think of it as a novel beverage. But for people in Asia, Russia, Europe, and yes, even here in the United States, it has been a staple for generations. So where did kombucha come from? The mythology claims 220 B.C. China, but there are no known records. The most common theories point to folk origins in Asia. Since kombucha is made from tea and the oldest relics of fermentation are traced back to China, it makes logical sense. From there, various stories link kombucha to the Silk Road, Genghis Khan in the steppes of Mongolia, the Samurai in Japan, and a “Dr. Kombu” from Korea, though again, written records are lacking.
We know for certain that there exist long family histories of making kombucha in Russia, where it was often brewed for a short time (3-4 days) to be served as a sort of homemade soda pop. Stories began to spread, telling of mountain towns where centenarians abounded, who all supposedly drank kombucha daily. These “legends” seem to follow everywhere kombucha goes, and in this case the stories of kombucha’s power led to it being studied in Russian universities as far back as the early 1900s. Owing to these stories, samples of kombucha cultures were collected from all over the Russian countryside and studied to uncover where this ancient brew might have come from and what health-giving properties it may provide.
During and after World War I, European soldiers stationed in Russia were introduced to the kombucha culture, sometimes even at prisoner camps. They brought it back to the European mainland, where it was especially popular in Germany. Waves of research would happen, in Germany and Russia especially, over the next 15 years, with hundreds of studies published about kombucha’s effect on everything from asthma to cancer and more. Paper after paper was printed in German scientific magazines of the day relating the ability of kombucha to have a positive effect, often on patients who had been suffering acutely.
While Germany was busy getting scientific, Italy, as it is wont, had a more passionate and brief love affair with kombucha. There, the culture was passed around like a chain letter, with scandalous handwritten instructions and a warning if they weren’t followed exactly. Taking these passions to the extreme, Italians, seeking the most blessed batch possible, began swiping holy water from the church fonts for brewing their sacred “booch.” This was a step too far for the priests, who started preaching against it from the pulpit, and so kombucha’s future in Italy was damned. Though there’s a neat pop song from the 1960s by Renato Corosone called “Stu Fungo Cinese” — find it on YouTube!
When World War II broke out, along came rationing of basic supplies like tea and sugar. With fewer nutrients available, kombucha brewing waned. The studies in Germany and Russia dried up around 1950, and kombucha receded into the underground again.
The brew gradually re-emerged in the United States in the 1960s as a hippie fad. As the ‘80s came along, a few scientists in Germany pick up the trail, and both the German First Lady Veronica Carstens (confirmed) and Ronald Reagan (unconfirmed) are linked to drinking kombucha daily.
It wasn’t until the early 1990s that kombucha was finally put into a bottle and sold on grocery shelves in the USA. GT Dave, a teenager from Los Angeles, bottled the brew made in his mother’s kitchen and sold his first cases to a local health food store, and thus an industry was born. The early 2000s saw an increase in brands being offered with the trend hitting a tipping point over the last few years. Now, kombucha’s popularity has spawned hundreds of craft and small brands around the world generating jobs and diversifying grocery shelves with healthier choices. Not to mention the industry has an estimated $800 million footprint worldwide, which is on pace to top $2 billion by 2024. Touted as the “21st century yogurt,” kombucha is here to stay and if you want to save a few dollars and make some tasty quaffs, then try brewing this ancient elixir at home!
Brewing Equipment & Process
Other than the SCOBY and starter liquid, the supplies used for making kombucha can often be found around the house. For step by step directions, refer to the recipes on at the end of this article. Tea is simple and only requires a pot or kettle. Stir in the sugar with a spoon of any material and cover the vessel with a tightly woven cloth such as a tea towel or even an old piece of t-shirt provided there aren’t any holes. Cheesecloth is not suitable as the weave is too loose and could allow fruit flies into the brew. Bottling can be done with the same technique you bottle beer.
Any type of real tea, i.e. Camellia sinensis, will provide the nutrients for a good brew, such as tannins and caffeine for fuel but also all the good things in tea, which are then fermented in the kombucha, making them more bioavailable. A blend of black and green tea is the most popular.
Mixing small amounts of herbal tea like yerba mate or rooibos or even some flavored teas may be acceptable, but those containing oils or other flavoring agents may negatively effect the brew, so stick to real tea for the best results. A steep range of 7–15 minutes provides an opportunity to adjust the flavor to your preference. If you like a stronger flavor, let the tea steep longer or even use a bit more tea.
Many types of fermenting vessels may be used in a variety of shapes and sizes. Glass, porcelain, stainless steel, and oak are all excellent choices for fermenting. Some food-grade plastic may be okay, depending on the type, but will wear out over time and may scratch, which makes them less desirable and not recommended. Very skinny vessels, tall but not wide, don’t ferment well due to less oxygen exposure for the aerobic brew. Use a tightly woven cotton cloth and rubber band to cover the vessel.
Next, find a place to ferment, typically the kitchen or pantry. Any warm room will do, provided it is out of direct sunlight and at optimal temperature. The yeast, the Y in SCOBY, prefer warmer temperatures (75–85 °F/24–29 °C is the best range, 80 °F/27 °C is the “sweet spot”) and they are key to acidifying the brew quickly to protect against mold. Direct sunlight can be antimicrobial, so keep in a lightly shaded (ambient light is fine) area that is also ventilated (cupboard works too). If your home doesn’t maintain such warm temperatures year-round, heaters and warming belts do a great job. Choose one with a thermostat to avoid frequent recalibration or repositioning.
The 7-21 day fermentation time varies based on brewing conditions (temperature, size of batch, etc.) and taste preference. If a sweeter flavor is preferred, ferment for a shorter time, as the longer it goes, the more sour it becomes, so, especially in your first few batches you brew, taste each day until you like the flavor. Also, similar to fermenting beer, the cooler the temperature, the longer the fermentation process takes. Taste is king so let your buds tell you when the brew has the sweet/sour balance that works for you.
The trace amount of ethanol produced by the fermentation process acts as a preservative and serves as nutrient for the bacteria. It hovers between 0.3-0.8% on average at bottling, however adding high sugar flavors and capping to store at room temperature can increase those levels to up to 2%. Hydrometers and refractometers can provide a ballpark estimate of the ABV, however excess particulate and multiple acids often skew readings higher. Carbonation will increase during second fermentation, so it is best to refrigerate once the bottle has built up the bubbles you crave to prevent it from carbonating further.
When it comes time for bottling, flip-tops or recycled kombucha bottles from the store are great options. Watch out for metal lids as they can react with the brew in the bottle, and if the cap is too loose, the fizz may fizzle. Kombucha is often available on tap and homebrewers who already have kegging systems may choose to keg their brew. Switch to higher-grade hoses to prevent leaching and store kegs between 40–60 °F (4–16 °C) to prevent over-foaming. Keep hoses and plastic fittings used for kombucha separate from those used for homebrewing.
Kombucha Flavoring Rule of Thumb
When the kombucha has the sweet-sour flavor that tastes best to you, that means primary fermentation is complete. Many people enjoy the brew just as it is without anything added. However, one of the most fun parts of brewing kombucha is flavoring it, also called secondary fermentation or 2F. Because of kombucha’s vinegar nature, it quickly absorbs nutrients and taste from whatever you put in there. And a little goes a long way! If too much flavoring is added, off flavors and/or too much carbonation will result, which can be dangerous and potentially cause bottles to burst, so start with less.
Also, the form of the flavoring will dictate how much is needed. For instance, you will need more apple pieces than apple juice. That’s because the sugars in the apple pieces are not as easily accessible as they are in the juice. But beware, adding juice is like adding liquid sugar, so always start with less. If you want to use fresh fruits and desire more flavoring to absorb, consider chopping up larger pieces into smaller ones, as more surface area increases the effectiveness.
Living it Up in the Hotel SCOBY-Fornia
A SCOBY hotel is the homebrewer’s backup stock. Kombucha is abundance in action as every batch yields a fresh SCOBY culture in addition to the original. This means extras are always being made and since the bacterial cellulose is durable, provided it’s kept moist and at the correct pH (2.5–3.8 pH), it will hang out for many weeks or months, until reintroduced to sweet tea. Cover with a cloth and it will grow a new SCOBY that will act as the lid while keeping bugs at bay.
The SCOBY hotel does need to be refreshed from time to time. Once the culture dries out, even just on top, it is vulnerable to mold. Remove dried out cultures and top off the jar from time to time with sweet tea or already fermented kombucha to keep them moist and at the correct pH. The more often it is refreshed, the healthier the SCOBY hotel and its residents will be.
Think Safety!
The safest and most successful way to make kombucha is by creating an environment tailored to its needs. Ideal brewing conditions include selecting the right type of brewing vessel, location, and temperature. The tips that follow will help you avoid common pitfalls and protect the brew from mold. Take care of the kombucha and it will take care of you!
The most important aspect of brewing safety is sourcing the culture. SCOBYs are not created equal and finding a culture that is healthy and strong ensures a lifetime of delicious kombucha. If you have a friend who is already brewing their own, that is a great place to start. Sometimes they are offered on community websites for a fee but without knowing the type of ingredients or conditions that the cultures are grown in, it is wisest to source a culture from a reputable vendor. Do be careful to avoid vinegar eels, which can be found in raw apple cider vinegar and often end up in SCOBYs offered on exchanges or even by low-quality sellers. A reputable source will provide at least one cup (240 mL) of strong starter (which is well-fermented kombucha, aged at least a couple of weeks or more) and a 4 oz. (113 g) of culture or larger for a one-gallon (4-L) batch of sweet tea. Some people still attempt to grow one from a commercial brand, and while sometimes a culture forms, because of the changes made to the brew for commercial purposes, often it does not. Even if a culture forms, they tend to be weaker and produce a weak or “watery” beverage, again due to the changes introduced to make storebought kombucha shelf stable.
Mold Inspection
As a living food, kombucha never expires or “goes bad” once it is brewed, but at the early stages, if the brew is not able to acidify quickly enough, that delicious sweet tea can be colonized by mold. Mold in kombucha only ever grows ON TOP of the new culture forming on the surface of the brew, which means it’s easy to spot. It comes in a wide variety of colors including black, blue, green, and white, and is fuzzy and/or dry. If disturbed, it leaves a powdery residue on the finger. If you suspect mold, lightly touch the spot and then check your fingers. If there is any dry residue, dispose of the kombucha including the SCOBY(s), sanitize the vessel and start with a fresh culture.
A common question is if the mold is just on top of the brew, can’t I save the SCOBY under the liquid? The answer is no. Once mold appears on top of the brew, the liquid and everything below has now been exposed to the spores. Brewing up a new batch with either the liquid or culture from the moldy batch almost always results in visible mold and leaves anyone consuming the brew potentially exposed. Accidentally consuming mold once is unpleasant but not so bad, but drinking it over and over could cause longer term issues.
Other than weak conditions, direct exposure to mold spores is the only other way kombucha contracts mold. Since the culture is prolific, we recommend storing extras in a SCOBY hotel. Take an inventory of the ideal conditions, tweak as needed, and then simply start over with a fresh culture from the hotel.
Cross Contamination
As a homebrewer you already know this: Fermentation is fun and when fermentation fervor strikes, nearly every nook or cranny in the house can be filled with yet another culture or project. Each ferment has its own unique microbiome of bacteria and yeasts depending on the substrate and end product being made. However, as a homebrewer, and if you also make wine at home, it is vital to understand the organisms in kombucha as they don’t play nice with most types of beer and wine.
Kombucha’s most common organisms — Brettanomyces bruxellensis (lambic and sour beer yeast) and Gluconacetobacter (vinegar) — are considered spoilage organisms for most beer styles and all wines. Some kombucha cultures may have different organisms like Saccharomyces cerevisiae or Lactobacillus, but according to a recent study conducted by Kombucha Brewers International and Oregon State University, it was found that most SCOBYs are Brettanomyces dominant.1
Contamination from wild yeasts in beer and wine can result in off flavors, hazy colors, and biofilms forming on the surface. They can also be an absolute nightmare not only due to the loss of product and the time, effort, and ingredients, but also the need to sanitize everything from top to bottom and then pray for no further contamination issues. Even commercial breweries have to take extreme measures when they add sour beers to their roster to prevent contamination. Some will go as far as to brew in separate facilities. Others do not permit employees working with sour beers to enter the other parts of the facility or require a change of clothes before re-entry along with wash up policies worthy of a chemical lab.
So unless your goal is to make only hybrid or sour beer styles, keep the kombucha as far away from your brewing or winemaking as possible. You might even house them in separate areas — i.e. basement or garage and follow the tips below to keep all of your ferments happy. We’d also recommend:
• Use separate brewing and decanting equipment to avoid cross contamination
• Adjust the brewing schedule so that each product is worked with on different days
• Store beer or wine yeast in airtight containers to prevent exposure to airborne wild yeast
Kombucha Recipes
This is Kombucha Kamp’s short-cut method for brewing up delicious kombucha quickly and safely. Since the yeast and bacteria are temperature-sensitive, the water should be body temperature (about 100 °F/38 °C) or lower before adding the SCOBY. To shorten the wait time, brew a tea concentrate that is then diluted with cool water to bring the temperature down quickly so you can immediately add the SCOBY and starter liquid. This ensures the sweet tea is not left out and potentially exposed to contaminants.
Kombucha
(1 gallon/4 L)
Scale up or down depending on the size of your fermentation vessel.
Equipment
Tea kettle
Fermenting vessel
Cloth cover
Rubber band
Ingredients
1 cup (200 g) sugar
4–6 loose leaf bags of tea (1 bag of tea = 1 tsp
SCOBY
1 cup starter liquid
1 gallon (4 L) purified/bottled water
Step by step
Boil 4 cups of purified water. Add hot water and tea bags to pot or fermenting vessel. Steep 7–15 minutes, then remove tea bags. Add sugar and stir to dissolve. Fill vessel most of the way with purified water, leaving just 1–2 inches (2.5–5 cm) from the top for breathing room with purified cold water. Add SCOBY and starter liquid. Place the cloth over the vessel to cover it and secure the cloth with the rubber band. Place the container in a warm (75–85 °F/24–29 °C is the best range, 80 °F/27 °C is ideal), ventilated area out of direct sunlight and do not disturb for seven days.
After 7 days, or when you are ready to taste your kombucha, gently insert a straw beneath the SCOBY and take a sip. If too tart, then reduce your fermentation cycle next time. If too sweet, allow to ferment for a few more days. Continue to taste every day or so until you reach your optimum flavor preference. Usual fermentation is between 7 and 21 days, depending on desired flavor. An optional next step is to decant and flavor if you would like.
Drink as desired! Start off with 4–8 oz. (120–240 mL) on an empty stomach in the morning, then with meals to help with digestion or as your body tells you it would like some more! Drink plenty of water to flush out any toxins released by the organic acids in kombucha.
Tips for Success:
Small variations in tea or sugar used are not a concern. Increase or decrease the amounts to find the flavor you prefer, but never use less than ¾ cup (150 g) sugar or 3 bags/tsp. of tea per gallon (4 L).
To dechlorinate tap water, if you prefer to use that vs. bottled or purified water, allow to sit out overnight uncovered or boil for
10 minutes and then cool to needed temperature.
Your SCOBY is a living organism — treat it with care and it will be your “booch buddy” for life!
Pear Ginger Kombucha
(16 oz./470-mL)
Hands down the MOST popular flavor of kombucha is ginger. Humans and ginger have a love affair as the piquant flavor not only intrigues the tongue but its digestive properties also settle the stomach. Before Prohibition, ginger beer was the most popular beverage in the United States and then became ginger ale once alcohol was outlawed. Enjoy the zippy zing of ginger by adding some to your kombucha! Pears provide a sweet, floral and fall flavor for the brew; of course any other type of fruit may be substituted in place of pears.
Ingredients
15 oz. (440 mL) kombucha
1 tsp. ginger juice or 1 Tbls. fresh ginger or 1 1⁄2 tsp. dried ginger pieces
1 Tbls. fresh, frozen, or canned pear, diced. Alternatively, you could use 1 1⁄2 tsp. pear juice
Step by step
Combine the ingredients in a 16-oz. (470-mL) bottle and cap tightly. Allow it to sit at room temperature for 1 to 3 days and then move to the fridge (if desired) to slow fermentation. If leaving the pieces in the bottle, consume within a week or it may be strained and stored for longer.
Tips for Success:
Ginger comes in many formats and they are all delicious providing varying levels of bite. For the most intense ginger flavor, use ginger juice. For a mellower flavor, cut up a thumb of ginger and use chunks or pieces. Since it’s more intense, less juice is needed than the pieces, so adjust the recipe according to your personal taste preference. The suggestions below are just that — use as a starting point and then tweak as desired.
Pomegranate Blueberry Kombucha
(16 oz./470-mL)
Both of these fruits pack an antioxidant punch and provide a beautiful deep hue thanks to the anthocyanins. We’d recommend using pomegranate juice or mashing the arils (pomegranate seeds) for the best flavor.
Ingredients
15 oz. (440 mL) kombucha
1 Tbls. pomegranate juice
2 Tbls. fresh or frozen blue berries, lightly mashed
Step by step
Combine the ingredients in a 16-oz. (470-mL) bottle and cap tightly. Allow it to sit at room temperature for 1 to 3 days and then move to the fridge (if desired) to slow fermentation. If leaving the pieces in the bottle, consume within a week or it may be strained and stored for longer.
Apple Pie Kombucha
(16 oz./470-mL)
Nothing says fall like apple pie, and with kombucha’s natural tang this is a match made in heaven. The additional cinnamon provides a deeper dimension to the flavor, but it may be omitted if preferred.
Ingredients
15 oz. (440 mL) kombucha
1⁄4 cup diced apples or 1 Tbls. apple juice
1⁄2 teaspoon chai spice (blend of dried ginger, nutmeg, clove, and orange peel)
1⁄4 teaspoon cinnamon chips
Step by step
Combine the ingredients in a 16-oz. (470-mL) bottle and cap tightly. Allow it to sit at room temperature for 1 to 3 days and then move to the fridge (if desired) to slow fermentation. If leaving the pieces in the bottle, consume within a week or it may be strained and stored for longer.
RESOURCES
1 https://kombuchabrewers.org/kbi-osu-dna-sequence-study-analysis-report/
Related Links:
• For more information and resources about brewing kombucha, visit the authors’ website: www.kombuchakamp.com
• Thinking about serving kombucha on your home kegerator? Find advice specific to kombucha brewers about sharing a draft system for bothkombucha and beer: byo.com/article/tune-your-taps/
