Sandor Katz rings the gong that also serves as a dinner bell to summon students to another session of his Fermentation Residency Program. He’s been called the “King of Fermentation,” and today, 14 disciples flock to him from both coasts and between, traveling the last three-and-a-half miles through Tennessee woods on a winding road that eventually turns to dirt before reaching the hilltop retreat 50 miles east of Nashville. Their classroom is a kitchen in a restored 1820s log cabin with a stone fireplace that reaches to the ceiling. They bunk in tents, use the outhouse when they must, and charge electronic devices when solar power is sufficient.
“We’ll talk about things we started, review the progress, start some more,” Katz says. His graying hair and beard are more closely cropped than in online videos and photos in which bushy mutton chops make him look a bit ferocious. His back is aching, but the more he talks the more he becomes animated, his hands soon conducting an invisible orchestra, a fermentation evangelist at the top of his game.
The New York Times once described Katz as “one of the unlikely rock stars of the American food scene.” He has taught hundreds of workshops around the world since his first food book, Wild Fermentation, was published in 2003. He often begins with sauerkraut to illustrate how simple it can be to ferment food and happily accepted Sandorkraut as a nickname, using it as his Twitter handle and making it part of his email address. His second fermentation book, The Art of Fermentation, won a James Beard award, and a framed certificate on the classroom kitchen wall verifies the Southern Foodways Alliance recognized him with its Craig Claiborne Lifetime Achievement Award.
The five-day residency program, offered two or three times a year, fills up more than six months in advance. Not everybody who answers a series of essay questions is accepted, and those who do pay up to $1,000 tuition (the fee varies). “It’s demystifying, the ability to see, to ask, to taste—you don’t get that with videos,” one attendee from Oregon tells me. Many are food activists. Like Katz, they’re so-called “fermentation revivalists” who will return home to teach others what they learned.
“Starting these things is the easy part. The challenging part is in the follow through,” Katz tells them, confessing that he hasn’t always done so himself. “Some things take days, weeks, months. The number one question is, ‘When is it done?’ It is done when you have the flavors you want.”
Brandon Jones at Nashville’s Yazoo Brewing has seen Katz share this enthusiasm in a beer festival setting. Jones hadn’t met Katz before inviting him to speak at the brewery’s first Funk Fest in 2013. But internet searches that included the word “fermentation” continually led him to Katz and his books
“He was captivating, his passion and ability to excite everyone in the room about food fermentation and beverage fermentation were amazing,” says Jones, who since collaborated to make a beer with Katz.
In the foreword to The Art of Fermentation, best-selling author Michael Pollan writes, “Since Louis Pasteur discovered the role of microbes in disease more than a century ago, most of us have found ourselves on a war footing with respect to bacteria.” It is a war Pollan, like Katz, thinks should end. He describes Katz as Post-Pasteurian, a label that also fits Jones, other members of the Sour and Wild Ale Guild, and still more like-minded brewers. They invite microbes to be partners.
Brewers are still learning to talk about such alliances as eloquently as Katz. He may describe something as “sour” (kimchi), because many of his fermentations are lactic and that flavor is a natural product of them, but he is as likely to use adjectives such as “delicious” (burdock, kefir) or “crunchy” (pickles). Even when invoking science to explain to an advanced class how a process works, he puts what was and is understood in the context of millennia. He makes both the process of fermentation and the results accessible.
“Molds are very different than bacteria and yeast. Bacteria and yeast just divide, divide, divide. Molds, they are much more like us. They have a more delineated life,” he says as students scribble notes. “With tempeh, the mold is white, the sporulation is black. With koji, the mold is white and sporulation is yellow.”
He grabs a carrot from the counter at the center of the kitchen, waving it with a flourish. “Spores are everywhere. This carrot, we couldn’t even count how many spores are on here,” he says. “Everything we are eating is covered with spores. But we only say, phyoo, when we see a mold has begun to develop on food. Until the time of Pasteur, nobody was really able to distinguish between different kinds of bacteria or different kinds of yeast. With molds there is this, like, literature going back thousands and thousands of years. What we call the Rhizopus mold they called white robed mold. The Aspergillus they called yellow robed mold.”
He compares the fermentation process to the life of a forest, in which a series of different trees follow each other as the dominant species, each succeeding type altering conditions to favor the next. The transformation is biologically complex, but creating the conditions can be simple. That it is natural does not mean sauerkraut makes itself.
“Sure, it will happen without us, but we guide it,” he says. “We develop techniques, create selective environments, find out which flavors are going to develop. One might give us a toxic mess. Another might not be toxic, but is not appealing. We are looking for microorganisms that can elevate the flavor.”
Fermenting foods is one of those trends of the moment where food and beer may intersect, much like plant-based menu items or all things local. Several months ago, Katz told a TEDx gathering in Sao Paulo, Brazil, that it’s quite absurd to recognize this as a new food trend. He listed products that leap to mind when fermentation is discussed, such as beer or wine, and those not everyone associates with fermentation, such as coffee and cheese. “What has changed is there is a growing awareness of the phenomenon of fermentation and a growing interest in it,” he told the audience.
Wild in the title of Katz’ first book does not necessarily mean feral. It is a way to distinguish between fermentation before Pasteur and much of fermentation since. “For 10,000 years, people who knew nothing about microbiology were doing this,” he says.
In the kitchen classroom, he explains the role koji, rice covered with mold that the class has already learned to make, plays in making sake. He describes both older techniques and modern ones. “That’s great that in the 20th century somebody has figured [a faster method] out, but my initial interest in fermentation is, ‘But how did they do that before?’” he says.
Pasteur’s Etudes sur la Biere, published in 1876, did not suddenly change beer. Although brewers may not have fully understood yeast, they learned centuries before they could reuse it. Of course, in the process, they passed along plenty of other microbes along with Saccharomyces cerevisiae (yeast). In 1829, Jean-Baptiste Vrancken, a teaching doctor at the University of Louvain, described 18th and 19th century trials in which brewers hauled the same equipment from one brewery to the next, used the exact same raw materials and processes, and never succeeded in repeating the same outcome.
Replicating beer from brewery-to-brewery and batch-to-batch became easier after Emile Christian Hansen at the Carlsberg Laboratory in Copenhagen perfected the method for obtaining pure cultures of yeast in 1883, and most brewers soon abandoned mixed cultures for “pure” single strains. It has not been written if those who today welcome a wider variety of microbes into their beers should be labeled Post-Hansen or Pre-Hansen.
“Mixed culture is probably the most annoying buzzword right now,” says Todd Steven Boera at Fonta Flora Brewery in North Carolina. “And we use it on our menu boards, labels, everywhere. If you asked 10 random people, I think you would get 10 different answers what it means.”
Mixed culture may not tell consumers as much about what to expect in a glass as Boera would like, but it makes sense in the context of the first of two beers Boera and Katz collaborated on. They met when Katz was in Asheville to sign books shortly after The Art of Fermentation was released. “Wild Fermentation had kind of turned my head around,” Boera says. He gave Katz a case of Post-Pasteur beers he had brewed, and a series of emails followed.
“I got into brewing through baking, and I always wanted to brew a Kvass,” Boera says. “Reading that book, coming across those ideas from somebody like him, it spoke to both of us.”
Kvass has a complicated history that may involve, in different settings, drinks made from old bread or from beets. Both are Eastern European. Both are sour. The beer Fonta Flora called Shopping Spree was brewed with local malted barley and rye and wheat and rye loaves of bread from a local brewery. After fermentation, it was aged on local spearmint, local chioggia beets, organic caraway seeds, and organic lemons.
Boera fermented it with one of two house mixed cultures, one he calls “Dandy” because the culture took what he calls “a cool turn toward acidity” the first time he used it to make a beer with fresh-picked dandelion flower heads.
“I didn’t have a clear vision how you would join all that in a beer,” says Katz. He includes a handful of beer recipes in his books and is excited to drink beers like Boera and Jones make, but there is a large space in the middle. “I tried to explore the lower tech traditions of brewing beer. Start with the seeds and turn that into beer,” he says.
He is wearing a t-shirt that says “Fermentation on Wheels,” but the next day he’s wearing one from Cantillon. Traveling in Africa 35 years ago, he discovered palm wines, millet beers, and sorghum beers. “I got this idea that beer is a much wider category. I’m enjoying watching what’s going on today.”
Although he and Katz discussed trying fermentation techniques Katz has catalogued visiting other cultures, Boera looks for something different than brewing knowledge from him. “Sandor was the first,” Boera says. “I am so embedded in beer. Getting to know other fermentation specialists, like David [Bauer] at [Asheville, NC’s] All Souls Pizza—they make brewers, others like myself, whole.”
He since collaborated to make Kvass with several other partners, both brewers and bakers. That’s led to more ideas. “I find bakers who are interested in baking bread with specific beer cultures,” he says. “I’ll try to make the liquid version and they’ll make the solid version.”
Jones first took notice of Katz because of their mutual interest in fermentation. “It was definitely the hot sauce,” he says. He kept seeing Katz mentioned when searched for information about using bacteria to make hot sauces. “I thought, ‘I have a lot of that in carboys in the garage.’”
Jones now trades fermented hot sauces with brewers most consumers associate with Post-Pasteurian beers. They occasionally include beer when they are shipping packages back and forth, but it is not the most important fermented product in the box. As it turns out, The brewers who have already pushed most deeply into the fermentation frontier are the ones looking beyond beer for still more ideas.
Since Katz spoke at Funk Fest in 2013, Jones has sometimes hosted students from his classes. “It’s the [fermented] food that gets them interested in the acidic component,” he says. He takes inspiration himself from the regional origins of the dishes Katz writes about. “Those kind of foods are so influenced by what is available within their culture. Every family has their own recipe. He opens that book up for us.”
He invited Katz to return to Funk Fest in 2017 after collaborating with him to brew a beer called Embrace the Funk Lichtenhainer. Jones chose Lichtenhainer, a sour, low-alcohol beer made with wheat and smoked malts, because he thought between his followers and Katz’ they might introduce the rarely brewed style to a wider audience. Katz provided sauerkraut and fermented beet cultures and Jones combined them with his house Lactobacillus to kick off fermentation.
“The public either loved it or absolutely hated it,” Jones says. “There was no middle ground on this beer. It was just too different for some folks.”
But it had the flavors he wanted.