Craft Kombucha: Everything You Need to Know About This Emerging Fizzy Beverage
By Ian Griffin - Booch News and Hannah Crum - KBI
What is Kombucha?
Like beer, kombucha is a fermented beverage; in fact, it is fermented tea. It has been around in one form or another for nearly 2,000 years. First brewed in China, it then spread to Japan and Russia. In the early 20th century, it became popular in Europe — following World War One, soldiers brought it back from Russia to Germany, Poland, and elsewhere.
It is a healthy and refreshing beverage full of B vitamins, organic acids, antioxidants, and trace amounts of alcohol. To make kombucha, starter liquid and a "kombucha mother," or "kombucha mushroom," also known as SCOBY (Symbiotic Culture of Bacteria and Yeast) is added to sweetened tea. After a fermentation period lasting 10-30 days or more, the liquid becomes increasingly tart. Sugar and tea are the primary food sources for the bacteria and yeast in the fermentation process.
Once the primary fermentation ends, many home brewers and commercial brands flavor the kombucha with fruits, herbs, or spices, allowing it to undergo secondary fermentation. This is when additional carbonation–a natural effervescence–will occur. Many brands also add CO2 to the final product for consistency and stability. Kombucha is known for its expansive flavor profiles that range from fruity to earthy to medicinal and savory.
The public and the scientific community have accepted fermented foods as functional foods. In the case of kombucha, fermentation yields not only delicious flavors but also increases antioxidant content, improving the health-promoting capacity of the tea. Finished kombucha typically has a pH range of 2.5 to 3.5. However, many commercial brands skew a little higher — likely to satisfy the mainstream consumers' palate, which doesn't tolerate sour, as well as a home brewer might. The fermentation produces a beverage with some natural carbonation, organic acids, nutrients in natural form, and trace amounts of alcohol. In the USA, the current legal limit to be considered a non-alcoholic beverage is 0.5% ABV. Many who avoid beer, wine, or other alcohol find kombucha a refreshing and safe alternative.
There are many types of commercial kombucha. They range from pasteurized or filtered shelf-stable kombucha to 'raw' or 'authentic' natural kombucha. There is also a growing market for hard kombucha, with ABV levels up to 11%.
Natural kombucha needs to be kept refrigerated since it is biologically active. The fermentation process continues as long as bacteria and yeast have sugars on which to feed. Yeasts are temperature-sensitive, and cold temperatures keep them less active. Trace amounts of ethanol are naturally produced by the fermentation process as a preservative to prevent mold and other pathogens from feasting on the delicious sweet tea. Keeping kombucha cold is essential to ensure the quality remains consistent and compliant.
The Market for Kombucha
Kombucha is a rapidly growing, multi-billion-dollar, worldwide market. The Booch News Worldwide Directory lists over 650 brands in the USA and over 2,500 worldwide. The market in the USA is dominated by a few large brands with many smaller 'craft' producers.
It's become commonplace to note that the kombucha industry is where craft beer was a few decades ago. Apart from a small number of national brands, such as GTs, Health-Ade, and Humm, and a few strong regional players, such as Mother Kombucha in the Southeast, most brands are selling direct to consumer with limited distribution. The craft beer world started in a similar fashion. In the 1980s, there were only around 40 breweries. By 1993, there were 446 breweries in operation; a year later, this grew to 601. Today, there are currently around 9,000 craft beer producers in the States.
Why Brew Kombucha?
Kombucha is an option for beer brewers looking to broaden their product offerings and differentiate themselves from the competition. Brewers Association economist Bart Watson states, "21% of breweries report some production of non-beer beverage alcohol such as seltzer, mead, and hard kombucha."
As kombucha volume continues to rise and the growth rate in craft beer sales slows down, brewers are looking for new ways to grow profitably. One option to consider is producing kombucha. Kombucha shares some of the process steps of beer making, e.g., brewing, fermentation, and packaging; however, there are some significant differences, as we'll explain below.
Kombucha production also uses equipment such as stainless-steel tanks, pumps, filters, etc., from the same vendors that serve the beer market. Alongside zero-alcohol beers, it appeals to the sober curious in your taproom. Many in the younger generation avoid alcohol altogether. Taprooms need to cater to designated drivers and 'Dry January' consumers. Many of these customers complain they don't want soda as an option, and an increasing number are asking why there isn't Kombucha on tap!
As we've noted, "Now thoroughly destigmatized, more bars and restaurants will include a dedicated non-alcoholic section on their beverage menus. These emerging products are expected not only to be offered as packaged goods in the on-premise, but they will take their place in the coveted draft program, especially where "local craft" is featured. Non- and low-alcohol options are a great way to increase ticket averages and responsibly upsell. This is a favorable trend customer-centric bars and restaurants will embrace."
Interest from Well-Established Brands
Kombucha has attracted the attention of large brewers and soda companies. The Coca-Cola Company has an interest in Health-Ade. Pepsi invested in Kevita. Molson Coors bought Clearly Kombucha. Belgian brewer Duvel Moortgat purchased a majority stake in Jarr Kombucha and moved production from the UK to Belgium. Michel Moortgat, CEO of Duvel, said the process used to make kombucha is "very similar to that of beer," adding, "it is the result of all-natural ingredients brewed to a tasteful drink by highly passionate people."
This is also true in the case of the rapidly growing hard kombucha category. The Boston Beer Co produces Wild Ginger Blueberry Kombucha with 4% ABV, and Deschutes Brewing Co produces Humm Zinger Kombucha Radler with 4.3% ABV. Sierra Nevada produces Strainge Beast with 7% ABV.
Anheuser-Busch bought a stake in Kombrewcha in 2017 and continues to innovate. It upped its hard kombucha alcohol content from 3.2% ABV to 4.4% ABV and then hard seltzers.
"The hard kombucha segment thus far has been dominated in the off-premise by five brands: Boochcraft (32% market share), GT's Classic Synergy Kombucha (22%), JuneShine (14%), Flying Embers (10%) and Kyla (6%), according to market research firm Nielsen."
Kombucha Brewing Guidelines
The brewing of the unfermented "liquid" is significantly different in beer vs. kombucha. The need for milling grains, mashing, and lautering beers does not exist with kombucha. For kombucha, the base ingredients are water, sugar, and tea. Tea can come in its raw solid form or in the form of tea extract. All that is needed is to ensure the tea flavor is adequately extracted (somewhat like what is done for hops), the sugar is well dissolved, and the sweet tea is rendered sterile through boiling. This can take place in the same types of kettle that beer brews are made in. From there, this sweet tea (kombucha's "wort") is then chilled before fermentation.
Other than in the case of sour beer production, a pure yeast culture is used in most beer fermentations. The yeast culture is chosen based on its desired flavors and process performance. In kombucha, a mixed culture is used. The yeast cells live in symbiosis with bacterial cells in a mixed culture called a SCOBY (symbiotic culture of bacteria and yeast).
A pellicle of cellulose is grown by the dominant bacteria (Acetobacter or Gluconacetobacter) and the yeasts (Brettanomyces bruxellensis and Saccharomyces species). These live in the pellicle and hang from the bottom of it. A "starter liquid" from a previously fermented kombucha, also known as "backslop," is added to the sweet tea mixture. Alternatively, a SCOBY can be procured from commercial suppliers: different SCOBYs will result in different flavor profiles in the final product.
The yeast in kombucha prefers simple sugars. If more complex sugars are used, this can lead to over-souring and off flavors. Sucrose ("table sugar"), which is made up of glucose and fructose, is ideal.
Fermentation temperature is key to the organisms' health and flavor development. Compared to lager yeasts which work best around 48 to 58 oF (9 to 14 oC), or ale yeasts which produce good results around 68 to 72 oF (20 to 22 oC), kombucha fermentations are often warmer around 75 to 85 oF (24 to 29 oC).
These warmer temperatures speed ethanol formation, which spikes early in the fermentation process. Then, when exposed to oxygen, some of the ethanol is converted into organic acids, lowering the kombucha's pH. This lower pH gives kombucha its signature tang, and it is not conducive to some of the microbial growth, including mold growth. Another difference between beer and kombucha fermentation is oxygen exposure, which for beer fermentations only takes place at the very start to enable yeast growth. Beer fermentations are most often (although not always) done in closed fermenters. Open fermenters increase the chances of microbial contamination from the ambient air, which can compete with the pure yeast culture and create off-flavors. An exception would be the production of some sour beers, which, similarly to kombucha, have higher acidity and lower pH.
In addition to fostering yeast growth, oxygen exposure can drastically change the beer flavor stability. In the case of kombucha, oxygen during fermentation is important. Fermenters are open, with just a tightly woven cloth above them, which allows CO2 to escape and oxygen and microorganisms to enter. Oxygen is a vital ingredient for kombucha because it helps convert some of the ethanol produced by the yeast into various compounds, including the organic acids previously mentioned.
Microbial contamination from other non-intended microorganisms can alter the flavor of a kombucha batch. Beer's sensitivity to potential microbial spoilage from other organisms requires good cleaning and sanitation procedures. These requirements also apply to kombucha production.
Scale-up in kombucha production can be tricky. Just as adjustments in yeast pitch rate, wort oxygenation, and fermentation temperature are needed to match the desired beer flavor at different fermenter volumes, process adjustments may be required when scaling up kombucha fermentations.
To produce hard kombucha, simply add sugars or select brewers' yeasts and procced with a second round of fermentation that creates alcohol.
Challenges of Brewing Kombucha
Just as the production of some sour beers represents a risk to the production of "regular" (i.e., non-sour beers), so it is for kombucha. For instance, the presence of Brettanomyces yeast is considered a spoilage organism for most beers (an exception being a Lambic style beer, for example) as it can cause a "barnyard" flavor. Microbial cross-contamination can quickly happen through ambient air and crevices in the tanks, hoses, seals, etc. A way to mitigate this risk is to designate a separate area (ideally a separate building) for kombucha production. When this is not possible, dedicated tanks, hoses, lines, valves, and a CIP system will also help reduce the risk. However, the challenge remains when equipment is shared between the two product streams (e.g., tanks or fillers). Because of these risks, some beer breweries opt not to produce or handle kombucha in their breweries.
When it comes to distribution, most kombucha is sold in glass bottles, although cans are on the rise. Only a small percentage is sold on tap. It's also necessary to educate the 'average' consumer, who won't be familiar with the taste – but craft beer lovers with a taste for sour beers are most likely to be open to experimenting.
"We brew our kombucha and First Street beer under the same roof in our Hastings, NE facility. But we keep both products well apart. In fact, the only thing they share is the floor drain." -- Jessi Hoft, Ensign Beverage.
Every batch of kombucha, when brewed with the right ingredients and temperature conditions, will yield a culture that can be used again (similarly to a good beer fermentation yielding a good crop of yeast that can be re-pitched). SCOBYs are famous for being highly reproductive, and a sign of a good quality batch is that the SCOBY will grow when left at room temperature. The SCOBY will also expand to the size of the vessel such that the larger the tank opening, the larger the resulting SCOBY will be. This prevents contamination from external organisms by creating a "lid" (which also helps create a more anaerobic fermentation condition underneath the SCOBY).
One of the best practices for kombucha breweries is to keep some extra cultures on hand in a "SCOBY Hotel." This stock needs to be carefully maintained (e.g., with added kombucha or sweet tea) to maintain its viability. SCOBYs are more resilient than lager or ale yeasts (which lose viability more rapidly and must be stored at colder temperatures). The stored SCOBYs are like an "insurance policy" in case of microbial contamination, poor SCOBY performance, or when volume scale-up is needed.
Often SCOBY pieces or disks will be used to start a larger-sized batch but given time, the new layers can get quite large and unwieldy. They also continue to thicken if left for extended periods. It is quite heavy as it is hydrophilic and can absorb over 100x its weight in liquid! When brewing kombucha in large tanks, the vessels need to have a manway that operators can safely go into the tank and physically remove the excess culture for cleaning by pushing it out the opening.
Excess culture has a variety of uses and can be offered as compost or animal feed to local farms, used to make SCOBY-based food products (e.g., SCOBY fruit leather), or even used for beauty treatments. While SCOBYs could potentially be sold as a byproduct, most companies don't have a way to monetize it and usually give it away to anyone who will use it.
Key Product Quality Metrics
In addition to sensory evaluation of every batch, kombucha brewers pay close attention to the product's final gravity, pH, titratable acidity, carbonation, and alcohol by volume (ABV). Unlike beer, close ABV control is needed, which is particularly critical if the product will be sold as a non-alcohol beverage (i.e., with an alcohol content of <0.5% by volume). Other parameters might become critical depending on the brand (e.g., color).
I'm Interested - What's Next?
If you are serious about kombucha, you should consider joining Kombucha Brewers International (KBI), the leading industry association. KBI strives to promote, protect, and enhance the overall well-being of the industry by creating an open line of communication between brewers, consumers, and regulators while advancing our industry through advocacy, education, research, and modern legislation.
Next, check out the ecosystem of integrated products and services we offer under three primary branded platforms: MarketMyBrewery offers craft brewers a robust cloud-based environment to manage sought-after product and taproom information, optimized to attract and retain loyal consumer and trade customers; BreweryDB is the world's largest curated database of independent craft breweries, now with listings for kombucha; and The Performance Platform converges accurate product knowledge with "ounce-by-ounce" customer data to raise the human and financial performance of draft beverage programs.
Ian Griffin publishes Booch News, the premier source of industry news and a Worldwide Directory listing over 2,600 commercial brands. Hannah Crum is the co-author of the best-selling “Big Book of Kombucha” and President of Kombucha Brewers International.