Kombucha is a sweet, naturally fermented carbonated beverage.

That much is certain.

The drink is made by combining sweetened tea with a living culture made up of lots of different kinds of yeasts and bacteria. When it’s allowed to sit for a long time, chemistry between the kombucha culture and the sugars in the tea produces both a fizz and a slight tangy taste—sort of like tea soda, but there’s a hint of sour complexity that adds a distinct character many find delicious. It’s best served cold.

For several years, bottled brands from across the country have appeared in area specialty stores, and increasingly local brewers have been appearing, each trying their hand at mastering this strange beverage creature. Kombucha on tap has recently been spotted being served at some area eateries, like the Roost in Northampton.

Beyond these basics facts and eye-witness accounts, though, the drink’s identity is more mystery than certainty. It’s neither a soda nor a beer; no one knows where kombucha came from, how its key ingredient originated, or even what it is exactly. Not brewers, not drinkers, not scientists.

No one.

It’s likely to have been around for thousands of years. Some believe the drink first came from Korea and then was introduced to neighboring nations. Both Japanese and Chinese emperors are said to have prized the red tea for its medicinal qualities. The first written record of the drink, though, is from Russia in the late 1800s—its ancestry before that is mostly speculation.

And what strange parents kombucha must have had!

Unlike most ingredients used in the culinary world, the kombucha culture isn’t depleted when it’s used to brew the tea. It grows.

Often mistaken for some kind of mushroom, kombucha is a living entity, but it has no known natural source. To make it, you need to find some already being cultivated. Ideally, you find someone already brewing with it and get them to give you a hunk—a tradition that has apparently been going on for millennia. If given sweetened tea to feast on, the strange clump of microbiology—a zoogleal mat is the proper scientific term—grows to fill its container. It looks like a wet pancake. When being bottled or served, the liquid is separated from the main culture (which will be used for the next batch), but every drink still contains the essence and microscopic traces of the “mother,” which gives it its flavor and its alleged healing properties.

As a raw, living product, kombucha is best enjoyed when it’s fresh and cold. This has meant that until the last 20 years, it’s only been brewed in small batches for local drinkers and has been largely unknown to mainstream audiences. Modern refrigeration and delivery systems have begun to change all that, turning kombucha into nearly a billion-dollar industry. Its strangeness and obscure origin apparently only add to its allure.

While some makers have capitalized on the legendary medicinal qualities, others have focused on developing its flavor and selling it as a refreshing drink for all ages. Recently, though, all kombucha brewers, regardless of their marketing philosophy, have discovered the challenges of selling a living food product in a marketplace designed and regulated to handle only inert, preserved foods.

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When asked in a recent Advocate interview about the medicinal properties of kombucha, Chris Kilham, UMass professor of ethnobotony and host of Fox television’s The Medicine Hunter [see “The Adventures of Black Vulture and Little Bear,” August 4, 2011], said, “The science just isn’t there.”

As someone who scours the globe looking for obscure plant life with rare healing qualities to be sold to cosmetic and pharmaceutical companies, Kilham explained that the jury was still out on kombucha. Not enough research had been done. While the culture wasn’t of particular professional interest to him, he also added that in his experience there was often good reason for folk remedies to be popular.

Despite the lack of scientific evidence of its healing qualities, on the East Coast kombucha is mostly found only in specialty food stores selling health and natural products. Along the Pacific, where it’s been popular since the mid-’90s, the drink can be found everywhere—including convenience stores and gas stations—made by a host of different brewers, but kombucha’s flavor doesn’t figure heavily in how it’s promoted.

Millennium Products, brewer of GT’s Organic Raw Kombucha, is the nation’s leading seller of kombucha, distributing more than a million bottles of product a year. Each has a label awash with text in tiny type promoting the drink’s qualities. Nowhere on the label of GT’s “original” variety is anything said about how it tastes. Rather, the majority of the verbiage is spent making vague claims with unspecific, scientific-sounding terminology.

Beneath the tagline “Living Food for the Living Body” appears a list of verbs such as rejuvenate, restore, revitalize, recharge, regenerate, and rebalance. They surround the words “enzymes + probiotics + detoxifiers.” Another block of text explains that “G.T. Dave began bottling Kombucha in 1995 after his mother’s success from drinking it during her battle with breast cancer.” The resulting product is “an elixir that immediately works with the body to restore balance and vitality;” for “best results,” we’re told, “drink at least one bottle a day. Product can be consumed before, during, or after meals.”

The one place where specific claims about the drink’s properties are made—saying in all caps that drinking kombucha supports things like “digestion, metabolism, immune system, appetite control, weight control, and anti-aging” capabilities—there’s an asterisk. Below, tinier text clarifies:

“*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”

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Katalyst Kombucha in Greenfield is the area’s largest brewer of the drink. Founder and CEO Will Savitri told the Advocate in a recent interview that before he’d learned anything about its history or purported health benefits, he’d been taken by the drink’s taste and peculiar character.

“I started out taking business classes when I went to college, but I dropped out and went into agriculture and holistic health, instead,” he said. “There was no way I was going to this business-thing, I thought. Little did I know…”

Shortly after graduating from UMass, on a trip to Hawaii about a decade ago, he had a brief encounter with kombucha that piqued his interest and led to further investigation. Still, when he was offered a sample of the culture a few years later, he wasn’t sure what he was getting himself into. He accepted the chunk of the “mushroom” from a brewer in Ashville, N. C. and drove home with it in a jar.

At the time, he was running the kitchen for the Sirius Community in Shutesbury, an intentional community whose members devote themselves to living in a way they find spiritually and ecologically conscious. Between baking bread and preparing meals, Savitri began experimenting with kombucha.

Soon there were jars fermenting all over his kitchen, crowding the shelves and counter space. He began sharing the results of his efforts, and within a short time he couldn’t keep up with the demand for more.

“It was really the people that wanted it that kept me going,” he said.

Jeff Canter, a friend at Sirius, suggested that Savitri ought to try selling his drink, and in 2005, after Savitri learned about the Western Mass. Food Processing Center, the local beverage company was born.

Run by the Franklin County Community Development Corporation, the processing center provides fledgling local food businesses with a space to prepare and promote their product. In a few short years, Savitri, the unlikely businessman, found himself in a quickly growing enterprise. Before he knew what had happened, he’d moved into his own facilities and had a staff on payroll, a national distributor, and customers across the country. In a few years, he’d multiplied his production capacity several times.

Like that of its West Coast competitors, Katalyst Kombucha’s marketing also leans toward the mystical. The company describes its brew as an “elixir,” and its website states that the “wisdom of Kombucha has been providing health and vitality … for thousands of years.” Katalyst’s claims of health benefits are more reserved, though, backed up by some data and embodied in the writings of amateur investigator Michael Roussin at www.kombucha-research.com. For $24.95, plus shipping and handling, a book is available that offers “more information and less hype” on kombucha’s healing properties.

The tone of the marketing is unfortunate, but when you talk to Savitri and Katalyst head brewer Sam Dibble, their knowledge and practical, meticulous approach to brewing shines through and seems far from flaky. They’re quick to dispel myths based on others’ claims about what the drink can do, and they’re specific when describing its properties.

“There are basically two kinds of acid in kombucha that give it its flavor: acetic acid and gluconic acid. Gluconic acid is what provides the primary health benefit,” Savitri said. “It essentially helps the liver in its detoxification process. The liver has its own antioxidant, something called glucuronic acid, and the gluconic acid in kombucha helps the other acid be more efficient in what it does.

“For a long time, the myth was that kombucha had glucuronic acid, the same stuff that’s in the liver,” he continued. “But that’s not the case. It’s never been found in tests, but still some of our competitors [such at G.T.’s Kombucha] include it in their labeling.”

“Kombucha also includes things called probiotics and prebiotics,” Dibble said. “With probiotics, you’re adding bacteria to your system to help with digestion. With prebiotics, you’re helping the body create the right balance of flora in the intestines. Even though a lot of other brewers push the benefits of probiotics, there’s research going on in Europe right now that shows the probiotics in kombucha—the actual bacteria in there—are probably broken down before they can do the body much good. It seems the prebiotics are more important.”

“It’s really the chemistry in the product that will help your system, rather than the biology in the product,” Savitri said.

While they’re happy to discuss the drink’s medicinal properties, it’s clear that Dibble’s chief concern and joy is what happens in the drinker’s mouth. Any beneficial after-effects are welcome, but secondary.

Working with Savitri, Dibble has concocted five varieties that are sure to satisfy the senses. Made with organic ingredients, they are brewed to balanced perfection. Their flagship variety, Ginger Devotion, offers a satisfying, sinus-arousing blast of intense Hawaiian ginger, and Bliss-Berry, which is made from Maine blueberries, has a fine mix of sweet and tart fruitiness. Pure Essence, their unflavored kombucha, is far less sour than other brands, and the taste of the black and green teas used is more pronounced.

“We currently brew 2,000 gallons a week,” Savitri said, “all from that initial hunk of kombucha culture I brought up from Ashville in a jar.”

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Last year, the meteoric rise in kombucha’s domestic sales hit a bump in the road, and for some small brewers, like Katalyst, the obstruction nearly overturned the beverage cart.

Maine scientists, who were testing a new brew for market, raised questions about the drink. Alleged health benefits weren’t at issue, though. It was how much alcohol the samples contained.

For a beverage to be sold as non-alcoholic, it needs to contain less than half a percent of alcohol. This may seem like a reasonable threshold, but as Dibble is quick to point out, most sweet beverages that are sold in stores—even juices and big brand sodas—have small traces of alcohol in them. When sugar and microbiology spend time together, alcohol is often produced as a result of the interaction; in many cases this is desirable, as the substance acts as a preservative.

Pasteurization has been used for decades to kill off the organisms that produce alcohol by subjecting the beverage to high heat. Because kombucha is a raw product that depends on its living cultures for flavor, it’s more difficult to control what happens in the bottle once it leaves the brewery.

Since the drink is refrigerated and served cold, the microbiological growth is slowed down and unlikely to be visible while the kombucha is fresh. Still, over time, strands will begin to appear. Particularly if the kombucha is left un-refrigerated, these threads will combine and turn into a small, dark cloud hovering in the drink. Though harmless and the result of a natural process, it’s also evidence that there’s more alcohol in the bottle than when the cap was first screwed on tight.

Before long, the concerns of the Maine investigators reached the ears of the legal team representing a national chain of grocers specializing in health foods. As a precautionary measure, the lawyers advised that all brands of kombucha be removed from store shelves. Overnight, the drink disappeared from the chain, forcing a multitude of consumers to look elsewhere for their fix.

The supermarket represented nearly 70 percent of all sales of Katalyst kombucha.

Though no threat to public health had been announced, and the Tariff and Trade Bureau—a government agency that polices alcoholic beverages—had reportedly told Savitri they were aware of the issue and were prepared to work with brewers to find a resolution, the corporate lawyers apparently weren’t taking any chances. Until brewers were prepared to guarantee that their drink met specifications, Savitri and other makers were informed, sales would not resume.

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For much of last summer, fall and winter, Savitri and Dibble devoted themselves to reducing the levels of yeast and bacteria that create the alcohol while still trying to maintain their signature flavors. The effort cost them months of time in research and development and many thousands of dollars they didn’t have.

While the supermarket chain began offering kombucha again last January, Katalyst’s product did not return to their shelves. Though the company had come into compliance, their relationship with the grocery giant had been soured. Having nearly been wrecked by what they saw as a questionable judgment on the part of the corporate lawyers, Savitri began rethinking his company’s ambitions and direction.

Interviewed nearly a year after calamity had struck, Savitri said that his business hadn’t quite made up the loss, but had almost filled the gap.

Dropping out of the race for national dominance, Katalyst set about cementing itself as the leading regional brand, redirecting its business focus mostly to the Northeast. To that end, it’s found two smaller, regional distributors who have been regaining ground selling to smaller grocers along the Atlantic.

The company has also started branching out in terms of production. Dibble does some brewing for hire, producing special recipes for a Brooklyn-based kombucha company, and Katalyst even collaborated with Dog Fish Brewing on a beer-kombucha mix for the Beer Advocate’s Boston’s Extreme Beer Fest earlier this year.

It’s not just fermented tea that’s brewing under Katalyst’s roof, either. Sharing the same space but operating under the name Green River Ambrosia, a sister company brews meads, Ginger Libation, and cyzers—all beverages most decidedly on the alcoholic side of things.

While Savitri and his partners have worked hard to keep the two kinds of product separate, since the embargo last year, G.T.’s has chosen something of a Goldilocks approach to defining its kombucha product line. It introduced three varieties of kombucha—a less than half a percent version to conform to regulations, a somewhat more than a half a percent version (“classic” kombucha for diehard fans of the original), and a downright alcoholic version. According to Dibble, the last two varieties require proof of age when being purchased in California. While the highest alcohol versions aren’t for sale out here yet, the other two varieties are sold in local stores without any clear distinction on their labels.