Marco Zappia ducks as he crosses the slightly-too-short threshold into the sauna in his office. A lanky 6-foot-2, he has to watch his head.

Having round-the-clock access to one of those build-your-own sauna kits that became so popular during the pandemic isn't just a perk of the job. Zappia, 30, and his team, 3leche, retrofitted the cedar cube into a kind of thermal cave, with 70% humidity and three heat zones that nudge along the careful cultivation of one very special kind of mold called koji.

Koji is the key ingredient in many of the food and drink experiments taking place inside the new 3leche Fermentation Lab in northeast Minneapolis' Food Building. Adding the fungus, which grows on starches, to raw ingredients and giving the mixture the time and space to ferment — that is, to undergo a chemical change — yields entirely new foods packed with depth, with umami, with funk. With koji's help, plain old soybeans, rice and wheat become mouthwatering miso, sake and soy sauce.

Employing a centuries-old Japanese technique for food transformation and preservation to make, say, an ancient Roman recipe for garum, a fish sauce-like condiment — and using only Minnesota-made ingredients — is one of the multifaceted ways 3leche's lab is breaking new, hyperlocal ground in an age-old tradition.

With the lab's opening this past winter, along with other efforts by area food and beverage experts, the Twin Cities is witnessing a 21st-century fermentation renaissance. After a processed-food-induced lull in the United States, practitioners, hobbyists and researchers are noticing increased consumer interest in fermented foods, whether because of the health or environmental benefits, or because, as Zappia says, "it's just deliciousness."

Fermentation involves adding a starter culture of living organisms — bacteria, yeast or mold — to foods. Those microbes find fuel there. They feed off the sugars and starches in the food, breaking them down into alcohols and acids that chemically alter the food's entire identity. Milk turns to yogurt, grapes to wine.

It's a complete reinvention. The process can be tumultuous, almost violent, at the micro level. Under an airtight seal, there could be foaming and bubbling and frothing. When making sake, for example, one stage of the conversion looks like rocks are tumbling in the tank.

Changing foods' chemical properties can be just as challenging as changing minds. "Instead of looking at mold as something to be scared of," Zappia says, "you can look at it like this has been happening for centuries."

'Adding magic'

The practice of fermenting foods actually dates back millennia, and many common foods we consume today are fermented — without many people even realizing it. Chocolate, cheese, dried salami and beers are all fermented.

"It is just part of the history of things, people figuring out ways to preserve foods and make them more interesting and, obviously, flavorful," says Sean Sherman, the chef and restaurateur behind the buzzy Minneapolis restaurant Owamni and the Indigenous Food Lab training center, both of which explore the Indigenous pantry.

In addition to improving the taste of ingredients, some studies have shown fermented foods that retain their live microbes (that is, they're not killed or removed through baking, roasting or filtering) can actually ease digestion and even stave off some illnesses.

Belal J. Muhialdin, a University of Minnesota researcher who comes from an Iraqi "pickling family" that has made and sold turshi, a fermented vegetable mix, for four generations, showed in a 2021 study that probiotics in fermented foods could stimulate the immune system to fight off respiratory and alimentary tract viruses.

Globally, fermentation was and continues to be an integral part of many people's diets. But highly controlled processed food production in the United States gradually shrunk the microbial makeup of the foods many Americans eat, to the point where the idea of fermentation has had to be reintroduced.

Kylene Guse and her sister Mel Guse were at the forefront of the movement when they opened Gyst Fermentation Bar in Minneapolis in 2014. On the menu: a "motherboard" of fermented meats and cheeses to pair with wine, and a peanut butter-and-kimchi sandwich.

"I think it did confuse people a little bit, like fermentation bar? What's that?" says Kylene Guse, who is now working toward her Ph.D. in nutrition at the University of Minnesota, where she studies the microbiome. "I think that is a product of our industrial food system that a lot of these really traditional processes have been lost."

Ahead of its time, the bar closed in 2018.

Just a few years later, home cooks are trading sourdough secrets. Refrigerators are filled with kombucha bottles. Grocery shelves are stocked with abundant brands of sauerkraut, gochujang and kefir. Bar menus are listing lacto-fermented brines among the ingredients in a cocktail, and restaurants, such as Minneapolis' Young Joni, offer kimchi as a side dish.

"If you told me that 30 years ago, I wouldn't have believed you," says Ann Kim, the chef and proprietor of Young Joni.

At her first restaurant, Pizzeria Lola, she broke ground by putting kimchi and gochujang, a fermented chili and rice paste, both staples of Korean cuisine, on one of her pies. It was a hard sell at first. Then people tasted it, and fell in love with the toppings' acidic funk, which complemented the tomato sauce and cut through the creaminess of the cheese.

"You're adding magic to food," Kim says. "As the late, great Prince said, 'Life, it ain't real funky unless it's got that pop.' And I think that's what fermentation is. That pop that takes something and transforms it into something bigger and better than what it was in a previous life."

Midwest inspiration

Intrepid experimenters like Zappia are the disciples of modern fermentation "revivalists" such as René Redzepi of Copenhagen's Noma, author Sandor Katz, and Cleveland restaurateur Jeremy Umansky, whose books, tips and recipes have been instrumental in raising the practice's profile.

Zappia — whose ultracool tattooed bartender vibe does a good job of masking the science nerd within — grew up in Loring Park and Linden Hills. He was home-schooled before enrolling early in college, and coast-hopped while he studied critical theory.

He was long interested in the way ingredients could be used and reused, since his days learning the cocktail trade at Northeast Social and running the bar at Eat Street Social, then consulting with bars around the country as a partner with Bittercube. He went on to launch the groundbreaking bar programs at Martina and Colita, where he aimed to generate little to no waste by crafting his own herbal liqueurs and fermenting citrus rinds to make cordials.

But the pandemic to a bartender was like bacteria to a glass of milk. It changed everything.

With his job on hold, Zappia went Up North to a colleague's family's farm. He was joined by longtime colleagues Dustin Nguyen and Adam Witherspoon, among others, and spent that first pandemic summer exploring hoop houses, growing perennials, botanicals and herbs. "It was just a really good time to go play in the dirt," he says.

Zappia, Nguyen and Witherspoon considered what to do next.

"The last 10 years, it's always been in a supporting capacity, where we are helping others achieve their visions and goals and aspirations. It's been beautiful and fantastic," Zappia says. "This is the first time we were able to step back and be like, what do we want to make?"

The answer was right beneath their feet.

"Chefs, bartenders, we just had a bad habit to cherry pick ingredients from all across the world, instead of looking inwards at your region and terroir. What does it even mean to be here in the Midwest?" he says.

To find the answer, the trio formed 3leche, a "cocktail commissary" that takes Minnesota's agricultural raw materials and turns them into deeply flavored ingredients that bartenders in the Twin Cities can use to make mixology easier, faster and less wasteful.

The company's three-pronged approach is maceration, fermentation and, once they are licensed for it, distillation. The latter focus, making spirits at their own distillery, is still in the planning stages, as is the goal to use profits from the sales to create a health care fund to support other bartenders.

To begin their explorations of Minnesota's terroir, they didn't have to look beyond northeast Minneapolis. Using scraps from their Food Building neighbors — Baker's Field Flour & Bread, Red Table Meat Co., Alemar Cheese Co., Skinny Jake's Fat Honey — 3leche is upcycling by-products of food production, reducing waste and creating exciting new flavors.

"It kind of feels like the closing of the circle, and it helps tell the story of how they're all really connected," says Kieran Folliard, the entrepreneur who founded the Food Building and gave 3leche a home there. "It's a different way of talking about organic, or regenerative, or local, because a lot of those things just become overused. Everything we're doing in the building is timeless."

By using mold and bacteria to transform Minnesota-made leftovers into new foods, the hard work of the farmer, the sacrifice of the livestock, the miraculous gift of the bees all get paid forward.

"There's the sustainability piece to it, but there's also a pride and a sense of belonging in situ, your place. What makes Minnesota and the Midwest special? Let's build those products and collaborate and share," Zappia says.

A line of nonalcoholic fermented botanical beverages, similar to kombucha, are already on menus, and some of the first events in the Food Building's new bar introduced 3leche's line of nonalcoholic, or proxy, vermouths.

Now, the team is developing recipes for miso by applying koji to stale bread (Zappia calls it "save the world miso"), and a nutty-cheesy marinade from whey that's leftover from the cheese-making process, called shio koji. "From a sustainability perspective, it's like straight hippie" stuff, he says.

They are mixing spent herbs and roots from their beverage-making with lard and beeswax to form candles that smell like mulled wine. They are collecting citrus rinds — probably a bar's biggest form of waste — from Twin Cities bars and crossing them with koji to create shelf-stable "super citrus" acid replacements. "It tastes remarkably like lemon wedges," says Zappia. "And it's carbon positive, which is rad."

"Rad," a go-to word in Zappia's lexicon, is just right. His team's radical approach to fermentation is to take an age-old tradition and make it new by looking inward, by celebrating home. 3leche is bottling the flavor of Minnesota.

In the sauna, called a koji muro, spores multiply on trays full of Kernza from Baker's Field, the miller and bakery next door.

Another partner in 3leche, Steven Befumo, packs Red Table pork scraps the color of cotton candy into a glass vat. He adds to it two agents of change: the koji-inoculated Kernza and salt. The mixture will rest in the sauna until it transforms into garum, an umami-packed sauce, with a depth and funkiness similar to fish sauce, that can be traced back to the Roman Empire.

Over the course of a month, the color will darken, the flavor deepen, "liquid gold" tamari will form on top, and an undeniable richness will develop along its marvelous journey from one thing into something else entirely.

Change is rad. And, says Zappia, "it's magical."