The art of edible bacteria: Noma’s David Zilber on the slow magic of fermentation

The self-taught specialist in the breakdown of food by micro-organisms is as much at home in the lab as the kitchen

Chef David Zilber reads books about the makeup of genetic material during staff meal. He calls quantum physics his jam, and is a self-taught specialist in the chemical breakdown of food substances by micro-organisms.

As the head of fermentation at Noma, Zilber, 33, coaxes new flavors out of jars whose contents are bubbling, rotting and pickling away to introduce at the cult-status Danish establishment (the restaurant was named best restaurant in the world four times, and was re-awarded two Michelin stars last week). Hints of a saffron kombucha hes working with waft out of the hot chamber, infusing the fermentation lab with south Asian fragrances.

Fermentation may currently be enjoying a phase of fascination that cycles through popular culture every few years, but the way Zilber sees it, the practice isnt making a comeback it never went away. Its always been there. It kept people alive. It served civilization, he says, sitting in one of the Copenhagen restaurants three greenhouses. I think fermentation is undergoing an understanding.

Hes probably sort of responsible for that, because what comes from Noma is devoured as the gospel. So when Nomas chef, Rene Redzepi, and Zilber published the Noma Guide to Fermentation last fall, it quickly became a modern edible bacteria bible. Across 100 recipes and nearly 500 pages, the guide covers Nomas best experiments with seven types of fermentation lactic acid, kombucha, vinegar, koji, miso, shoyu and garum all of which make appearances on every dish at the restaurant.

Rene felt a zeitgeist around fermentation and the literature supporting it was lacking, and if any restaurant on Earth was going to be able to speak to it, it was us, Zilber says.

David Zilber head of fermentation at Noma, photographed at his home in Copenhagen. Photograph: Anders Rye Skjoldjensen/The Guardian

In the guide, they demonstrate how to crank one ingredient out to its punkest form, sometimes with the help of just salt a technique called lacto-fermentation. The techniques they harness in the lab can span months; in the guide they span pages 14 in the case of the very first recipe, lacto plums even though it requires just ripe plums and non-iodized salt.

A two-page photo grid shows the plums evolution as they ferment in a vacuum-sealed bag. By the seventh day they look intergalactic, like 20 suns exploding, but its actually just the fruit bursting through loosened skin made to have a caper-like sharpness and bathing in its own juice made lemon-sour thanks to fermentation.

The plums take five to seven days. The shortest recipe in the guide is for koji when mold on rice grains or barley converts starch to sugar, contributing an intense sweetness which is ready in two days.

A requirement for some recipes that may seem excessive to the humble home cook is a fermentation chamber to control humidity and temperature. In the guide, a photo shows Zilber in an apron, shoulder-length individual braids gathered into a low ponytail, demonstrating how to build a DIY version with a speed rack, sheet pans and a space heater.

Fermentation is definitely a commitment. It is committing to something. Its being responsible for life and watching it grow. Its a slow and patient process, his Toronto-Canadian roots becoming clear with his pronunciation of the a long O in pro-cess. But its also being rewarded.

Some recipes require an unusual degree of dedication. The cep shoyu, AKA porcini mushrooms, have to be stirred and tasted every day for the first two weeks, and are only ready to eat about four months after that. The garums, or fish sauces, are ready in about 10 weeks. The hardest concept to grasp about fermentation is the waiting.

Whether our frenzied society is really capable of adopting the slow methods of fermentation or not doesnt seem to matter to Zilber. Its just shared knowledge, he says. But if people do it, they will become more invested in what they eat. How its going to change cuisine going forward and peoples understanding of what cooking is when people understand that all those traditional [fermentation] recipes are toolboxes they can then use to further manipulate the world of food into whatever direction you want.

In broad terms, fermentation is a way of finding new flavors, which is the main role of the lab at Noma. The kitchen can start with a concept for a dish and then a chef comes and says, Oh, I need 15% more sour umami flavor. Hmmm. Is that going to come from freeze-dried gooseberries or a kombucha reduction or a light vinegar? Zilber says. Its not like we have this dish and can you ferment it and then plug it back in. But its what makes everything taste so rich and complete and full and complex and layered.

Ten rooms some sweet, some sour, some musky and pungent represent the various transformations of ingredients, expressed by different scents, and provide an ever-evolving pantry for the restaurant. The hot room, kept at 60C (140F), smells like black garlic right now. The miso room smells like ageing miso and other umami-rich caramelized flavors.

Inoculated barley smells like apricots and honeysuckle at 48 hours. It really fills the room, he says of this finicky form of koji, a closeup photo of which appears in the guide across two pages, resembling a birds-eye view of a densely packed wet cotton field.

If you taste the menu, and then you walk into the fermentation lab, into the miso room, and its like, Oh, thats the smell thats been in my mouth all night, he says.

Zilber and the four or five other chefs in the lab also just experiment with reactions of food to various applications of fermentation. They tried out wearing white lab coats, like scientists, but quickly scratched that (It looked like a Colgate commercial where they develop some new teeth whitening, he says, laughing).

David Zilber. Photograph: Anders Rye Skjoldjensen/The Guardian

I did some weirrrrd projects, Zilber says about what helped earn his promotion from chef de partie to director of the lab in 18 months.

On Saturdays, Nomas chefs are invited to present ideas they could see on the menu there. I would just go completely left field. Id make dishes of food that required artists statements.

His projects developed a reputation for warranting 45-minute debates like the one where four diners eat the same ingredients prepared and arranged differently and with blinders as an exercise in subjectivity in taste in place of the usual five-minute critique. Interns were getting into heated conversations with the head chef about what was food and what was art and that was exactly what I wanted to do.

The first time Redzepi saw one of his projects, Zilber says he looked shocked. Usually Rene clearly tells you what he likes and doesnt like. But all he could say was, Well, David, thank you for disrupting projects this week. I took that as having accomplished something. And all around just being a smartass probably covered the rest.

Smartass in his case means polymath, with some of that encyclopedic databank spilling on to his skin: a tattoo of a map of the solar system within the Milky Way on his right arm, the Schrdinger equation, a description of wave function in physics, on his left.

Zilber hasnt read a novel in 12 years; he is addicted to non-fiction. He reads during staff meal instead of being on Tinder or Instagram, he says and just finished The Tangled Tree, a history of how bacteria and horizontal gene transfer upend conceptions of the way species evolve on Earth. Hes currently reading Tamed, a book about the domestication of the 10 most important species to mankind.

He relates his fascination with evolution to fermentation: There are fundamental truths about the way Earth works that absolutely manifest themselves in any facet of life, especially in the wild and chaotic biological ones that you see in fermentation, he says.

I sneak a little bit of that into the book in the miso chapter, when I equate this Korean idea of son-mat (or hand-taste, meaning each fermenters product will taste a bit different each time) to chaos theory. There are parallels between the way fermentation happens and the way the universe happens and I think its beautiful, he says before stopping himself. Is that too much?

Perhaps, to be in charge of inventing flavors in a lab at one of the most celebrated restaurants in the world is to be consumed by the idea of what else is out there. For Zilber, fermentation is a never-ending exploration.

Its like poking a hole in a piece of paper and holding it up to the night sky peering through it and being like, aha, the Milky Way. Theres something else out there thats capable of producing flavors that people have never tasted or imagined before, he says. Thats the end game.

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