Emily Edon couldn't help making a face when she took her first swig of kombucha.

"It tasted vinegary and that put me off," said the 26-year-old Bloomington resident, wrinkling her nose at the memory.

But by the time she had drained that inaugural bottle, the fermented tea beverage had started to appeal to her.

"It's supposed to be good for you. Now I'm kind of obsessed with it. I like everything about it but the price," Edon said of the drink, which sells for between $3 and $4.

"I would drink one a day if it wasn't so expensive."

On a recent bitterly cold Saturday, Edon and a friend spent the better part of an afternoon at a sold-out class in St. Paul. They joined two dozen other fans of the tangy drink to learn how to brew batches of kombucha in their own kitchens.

"That's why I started making it at home, because it's really cheap to produce," said the instructor, Bryan Bertsch. Thirteen years ago, he started brewing kombucha to quench his personal thirst.

In 2010 he started commercial production with his Minneapolis-made Deane's Kombucha. He now markets 15 flavors of the beverage. (Deane is Bertsch's middle name.)

Kombucha is brewed by combining water with tea, sugar and a symbiotic culture of bacteria and yeast. While it ferments for a week or so, the microorganisms form a gelatinous floating structure known as a SCOBY (for symbiotic colony of bacteria and yeast).

Bottling it in a second fermentation with the addition of fruit, fruit juice, herbs or spices creates added fizziness and flavor.

"It's a living beverage, so I recommend that you brew it in glass. It's kind of fun to watch what's going on in there," said Bertsch, who provided his students with printed instructions and two bottles of starter liquid from batches of his product. "You can see the strings hanging in it, that's a natural byproduct of the fermentation process. It's like watching a lava lamp."

A history of flavor

Although kombucha is often described as an acquired taste, it appears that a lot of people have, in fact, acquired it. Thought to have originated in Asia hundreds of years ago, its contemporary popularity has grown dramatically since the first U.S. commercial version of the effervescent drink was introduced two decades ago. Today it has moved from limited availability at co-ops and natural food stores to mainstream supermarkets.

According to retail analyst Micro Market Monitor, there was a nearly fivefold increase in global kombucha sales from 2013 to 2015, to about $600 million a year, a robust figure far beyond the amount that dietary fads achieve. Projections suggest those sales will hit $1.8 billion by 2020.

"People like the flavor, but the main reason people want it is for its health benefits," Bertsch said.

Kombucha falls in the functional foods category — those edible products that are said to enhance health. Proponents of the drink call it a natural detoxifier that aids in digestion, promotes immunity, enhances energy — and is a great hangover cure.

But those purported benefits are challenged by skeptics. A page on WebMD found "insufficient evidence" for kombucha's medicinal value. Writing on the Mayo Clinic website, Dr. Brent Bauer, director of Mayo's Department of Internal Medicine's Complementary and Integrative Medicine Program, also noted that there's no solid support for the health claims.

"There have been reports of adverse effects, such as stomach upset, infections and allergic reactions in kombucha tea drinkers," Bauer wrote. "At the same time, several cases of harm have been reported. Therefore, the prudent approach is to avoid kombucha tea until more definitive information is available."

But Dr. Greg Plotnikoff sees no reason to wait.

"I'm a fan. I drink a lot of it," said Plotnikoff, a board-certified internist and pediatrician at Minnesota Natural Medicine in Vandals Heights. He's the co-author of "Trust Your Gut," a book about resolving digestive problems.

"Kombucha is a prebiotic, meaning that it supports the growth of beneficial bacteria — the probiotics — that are really important to good ecology in the gut," he said. "Gut health is the foundation of all health, so focusing on it is one of the best ways to be proactive about overall well-being."

Plotnikoff concedes that while the beverage has not been specifically researched, he cites several studies of laboratory mice that indicate that kombucha reduced inflammation and built resilience against toxins.

"Consuming fermented foods is a great way of supporting harmony and balance in the gut," he said. "More evidence is accumulating that documents that what goes on in our gut affects our entire body."

Inspired by craft beer

After selling his Deane's Kombucha for five years, Bertsch, 43, quit his day job at a distribution company last year to devote his full efforts to his business.

He credits the thriving Minnesota craft beer scene for giving him the confidence to start producing his kombucha for customers.

"I was watching the beer market explode, and I saw that people are interested in the art and the taste of fermented beverages when they are well executed," he said.

Now he's a one-man band, producing and promoting the flavored kombucha that he brews in 30-gallon oak barrels in his commercial kitchen.

Bertsch has experimented with innovative flavors, and now offers a delicate pear-sage version of his product, along with a buckwheat honey that plays off the kombucha's tartness, and a pale pink bloody mary-flavored variety that comes with the tease of horseradish.

Bertsch wants his naturally carbonated product to be poured from a keg as well as being sipped by the bottle. He began his business by selling by-the-glass at farmers markets. Now Deane's Kombucha is on tap at the Wedge Table and Eastlake Craft Brewery in Minneapolis, Quixotic Coffee and Brasa in St. Paul. It's recently been added at restaurants in Duluth and Fargo, N.D.

Attracting a crowd

Bertsch has been teaching monthly kombucha-making sessions for eight years, with students paying $25 to $35 to attend the sessions, often held at co-ops or natural food stores.

"I'm an IT geek and I like doing kitchen chemistry," said Lynn Loynachan, 53, who took the class last year and has continuously brewed kombucha ever since, turning out two gallons per week in her Woodbury kitchen.

"It's much less complicated than I thought it would be," said Loynachan, who has gotten into the habit of sipping her homemade kombucha from a wine glass.

"I make more than I can drink and give my overflow to friends. They give me the bottles back because they want more."

Bertsch encourages his neophyte fermenters to experiment with the number of tea bags they use, the tea steeping time, which determines the strength of the batch, and with flavor combinations.

He also urges them to jot down details of the way they vary their early batches.

"That way, when you have that brilliant batch, you know what you did to make it just right for your personal preference," he said.

"It's a raw drink and it's alive, so open your heart to it. Listen to it and give it love. It wants to get into your belly."

Kevyn Burger is a Minneapolis freelance writer.