Cooked: A Natural History of Transformation

by Michael Pollan

  I grew up on that field of battle. My mother instilled a deep fear of molds, trichinosis, botulism, and countless other unnamed germs possibly lurking in our food. She maintained an under-the-sink and in-the-medicine-cabinet antimicrobial arsenal stocked with Lysol, Clorox, Listerine, and Bactine. A touch of white on a wedge of cheese was enough to condemn it. The slightest dent in a can of food consigned it to the trash, no matter that the dent came from being dropped on the floor. You never know; could be botulism; better safe than sorry.

  The molds and bacteria now have a small but growing tribe of human defenders. These post-Pasteurians,* as they sometimes call themselves, form one of the more curious subcultures in America. It is sometimes called the fermentation underground, a word that seems fitting, given the fierceness of their devotion to microbes and their willingness to break the law to consume them. These are people who will fight for the right to drink unpasteurized milk and eat unpasteurized cheeses, who ferment all manner of foods and beverages using “wild cultures” exclusively, and who generally believe the time has come for humanity to renegotiate the terms of its relationship with “the microcosmos”—the biologist Lynn Margulis’s term for the unseen universe of microbes all around and within us. Much more than a way to prepare and preserve food, fermentation for these people becomes a political and ecological act, a way to engage with the bacteria and fungi, honor our coevolutionary interdependence, and get over our self-destructive germophobia. It seems there’s a lot more going on in a crock of homemade sauerkraut than a handful of lactobacilli species diligently fermenting the sugars in a cabbage; at stake in that crock is our whole relationship to nature.

  The man who first taught me how to make sauerkraut is a leader of this underground and possibly the most famous fermento in America. Sandor Katz is the Johnny Appleseed of fermentation, a fiftyish writer, advocate, and itinerant teacher with a suitably retro appearance. Six feet tall and loose limbed, he has electrified muttonchops that drift together and link chops above his lips to form a bushy mustache that would not have been out of place in nineteenth-century America; Katz could easily pass for a Civil War veteran. Yet Katz grew up on the Upper West Side of Manhattan, eating sour dills from Zabar’s, studied history at Brown, and learned the arts of fermentation while living on “a fairy commune” in rural Tennessee; he had to figure out something to do with all the surplus produce from the garden. Katz has been HIV-positive since 1991, and partly credits a diet rich in “live culture” foods—i.e., ones teeming with living bacteria—for his continued vigor and good health.

  Since his first book, Wild Fermentation, was published in 2003, Katz has traveled the country teaching people how to make kraut and kimchi, pickled vegetables of every kind, mead and beer and wine, miso, natto, tempeh, kvass, smreka, sourdough bread, ogi, kefir, cheese, yogurt, labneh, tej, shrub, kishk, and dozens of other obscure fermentations I had never heard of. But, like John Chapman, whose offer of apple trees was really just a way to get his foot in the door so that he might expound his Swedenborgian gospel, Sandor Katz’s sauerkraut teachings open onto an evangelism, too—a microbial gospel. Both characters would have us turn our attention to an invisible realm, both plied their message along a frontier, and both bid us to see the natural world around us in a striking new light.

  But first the kraut. I caught up with Sandor at a health-food store in Alameda, California, where he was conducting a workshop. He was in town on a two-week tour of the Bay Area, offering classes, visiting pickle makers, participating in panels and “culture swaps” and “skill shares,” leading a bicycle tour–cum–tasting of home brews in the East Bay (only a few minor accidents were reported), and giving the keynote address at the third annual Fermentation Festival up in Freestone. (About which more later.) Here in Alameda, on a weekday afternoon, twenty aspiring fermenters had gathered with their notebooks around the café tables in the store’s sunny window to watch Sandor make sauerkraut and expound on “cultural revival.”

  “So really there’s not much to it. Chop or grate the cabbage, fine or rough, however you like it. Chopper’s choice, I always say.” I was immediately struck by Sandor’s anticharismatic mode of address. He is utterly unpretentious, refusing to mystify his expertise in any way. If anything, he makes what he does sound rather ho-hum. Sandor also refuses to be categorical about anything. His answer to every other question is “Well, it is and it isn’t,” or “Yes and no,” or “It really depends,” or “Every fermentation is different.” His shrug gets a good workout, too.

  I came to see that his diffidence reflects both a practical and a philosophical stance. There is no “right” way to ferment anything, no hard and fast rules. And, given how little we understand about the microbial world, one where bacteria can trade genes and their exact identities are often up for grabs, it would be hubris to pretend to certainty. As I realized when I was learning to bake bread, for a human to have a good working relationship with bacteria and fungi, it helps to possess a healthy degree of negative capability. These are cultures you can nudge, perhaps even manage, but never entirely control, or even comprehend. “Nature imperfectly mastered,” a phrase I heard from a cheese maker, stands as a pretty good definition of this work, which has much in common with gardening. Every ferment retains a certain element of unknowable wildness.

  While Sandor walked us through the nuts and bolts of pickling—a term serious fermenters apply to all vegetable ferments, not just cucumbers—he occasionally wandered off the how-to trail, sauntering into the political, ecological, and philosophical implications of fermentation. He regards his work as a form of “cultural revival”—by which he has in mind both meanings of the word “culture,” the microbial and the human. The revival of these food cultures depends on reviving the microbial cultures that create them, and the reverse is true as well. The word “ferment,” too, had a double meaning: “When people get excited about ideas, they get bubbly. I want to leave you with thoughts of social and political ferment, too.” The DIY skills he was imparting held within them an implicit politics. They would help people take back control of their diet from the corporations, whose “dead food” was damaging our health and “homogenizing” our experience. Mastery of the fermentation arts could also help us break the dependency of consumerism, rebuild local food systems (since fermented foods allow us to eat locally all year long), and rediscover the “pleasures and wonders of transformation.”

  “As a culture we need to rehabilitate the image of bacteria. They are our ancestors and our allies. Did you know you have more bacterial cells in your body than human cells? By a factor of ten! Most of the DNA we’re carrying around is microbial DNA, not human. Which raises an interesting question: Who exactly are we?” Katz suggested that a visitor from another planet would be forced to conclude who we are is a superorganism, a symbiotic community of several hundred species, with Homo sapiens serving as unwitting front man and ambulatory device. “We need them and they need us.”

  Okay, but what about microbial disease? “To declare war on ninety-nine percent of bacteria when less than one percent of them threaten our health makes no sense. Many of the bacteria we’re killing are our protectors.” In fact, the twentieth-century war on bacteria—with its profligate use of antibiotics, and routine sterilization of food—has undermined our health by wrecking the ecology of our gut. “For the first time in human history, it has become important to consciously replenish our microflora.” Hence the urgency of cultural revival. And it all begins with sauerkraut, the “gateway ferment” he had come here to empower us to make ourselves.

  In modern civilization’s war on bacteria, Sandor Katz is a conscientious objector—a pacifist. He has a remarkably relaxed attitude toward all
microbes, the ones you want in your food as well as the ones you don’t. He’s notably relaxed about sanitation, too. “I clean my bowls, crocks, and utensils with soapy water, but you really don’t need to sterilize them. These practices all developed in a nonsterile world, after all. The lactic acid will take care of it.”

  He explained how this worked. The bacteria responsible for the fermentation were wild strains of lactic acid bacteria* already present on the raw vegetables, including Leuconostoc mesenteroides, Lactobacillus brevis, and Lactobacillus plantarum. These bugs are halophilic (salt-tolerant) anaerobes, so thrive in the airless saline niche the pickler has created for them in the brine. They get right to work eating the sugars in the vegetables, multiplying furiously, and releasing copious amounts of lactic acid—which they produce for the purpose of poisoning their competitors.

  Katz likened a sauerkraut to a forest ecosystem, in which one type of bacteria succeeds another, each species transforming the environment in such a way as to prepare the ground for the next. In a vegetable ferment, each succeeding species is more acid tolerant than the last, until the environment arrives at a climax stage dominated by L. plantarum—the great acid-loving oak of the pickle ecosystem. All that lactic acid gives the ferment its tang as well as its keeping qualities, since few other microbes can survive in such a low pH environment. The idea that the safety of a food is guaranteed by the bacteria still alive in it is a hard one for us Pasteurians to stomach. I seriously doubted I could ever sell it to my mother.

  Sandor emphasized that oxygen is the enemy of a vegetable ferment, but should the uppermost layer of cabbage begin to rot, it is no cause for alarm. Though it should be removed, he advised, lest the molds send their filaments down into the kraut and reduce it to mush with their pectin- and cellulose-destroying enzymes. Katz described digging “perfectly good” sauerkraut out from under a layer of moldy slime, and “off odors” that sometimes developed during the course of fermentation, but these were nothing to get upset about. But what if things in there got seriously funky? someone wanted to know. Began to smell like a dead animal, say? Sandor shrugged. “You have to trust your senses.” As he passed around little plastic cups filled with a radish kraut he had kept in a barrel in his basement since the previous summer, I thought about my mother, vigilantly tossing out her dented cans on suspicion of botulism. The strong, just-this-side-of-funky smell of Sandor’s radish kraut wafted through the store. But the kraut tasted good: still crunchy, with a bracing sour tang.

  Before there were cans, before there were freezers and refrigerators, fermentation was the main way people preserved food from spoiling. The very earliest fermentations were done in pits dug into the earth, lined with leaves, and filled with various foodstuffs: vegetables, meat, fish, grain, tubers, fruits, whatever. The earth kept the temperature low and steady and perhaps also contributed some helpful microbes. Under these conditions a lactofermentation (that is, a fermentation conducted by lactobacilli) would commence within days, and eventually produce enough lactic acid to preserve the food for months, sometimes even years. In the 1980s an abandoned fermentation pit estimated to be three hundred years old was discovered in Fiji. The breadfruit in it had been reduced to a sour mush, but it was reported to be “still in edible condition.” (You first.)

  Pit fermentation is still practiced here and there around the world. I’ve seen whole cabbages fermenting in dirt trenches in China, a practice also common in certain parts of Austria and Poland. The Inuit still bury fish in the Arctic tundra, and in the South Pacific, starchy root vegetables like cassava and taro are buried in pits lined with banana leaves. In Iceland not long ago, I had the dubious privilege of tasting hákarl: shark that has been buried underground for several months, until it develops the texture and blinding ammonia stink of an exceptionally strong cheese. What began as a practical necessity—to get through the winter without starving—has become a cherished delicacy, at least among Icelanders. Whenever I read that “rotten” is a culturally constructed concept, as anthropologists tell us, I think back on my hákarl and nod in assent.

  Nowadays, pit fermentation strikes most of us as primitive, strange, and unsanitary, yet we think nothing of aging cheeses underground, in caves, which is not so very different. And how different is a pit fermentation, really, from fermenting food in a crock? “Earthenware,” as it’s called, is really just earth once removed, cleaner and more portable perhaps, but otherwise the same basic idea. Even today, Koreans bury their child-sized crocks of kimchi in the backyard, in order to maintain the even, cool conditions that the lactobacilli prefer. The earthenware crock is a good reminder that every ferment is food and drink stolen, or borrowed, from the earth, by temporarily diverting its microbial-gravitational pull to our own ends. Everyone knows who stole the power of fire from the gods for the benefit of humankind, but who is the Prometheus of pickling? If mythology lacks for one, it is only because fermenting a heap of vegetables or grain seems a less heroic mode of engaging with nature than putting a large animal onto a fire. (There’s much less to look at, too.) But the argument can be made (and has been, by Sandor Katz, among others) that humankind’s mastery of fermentation rivals the control of fire in its importance to our success as a species.

  If there is a culture that does not practice some fermentation of food or drink, anthropologists have yet to discover it. Fermentation would appear to be a cultural universal, and remains one of the most important ways that food is processed. Even today, as much as a third of the food in the world’s diet is produced in a process involving fermentation. Many of these foods and drinks happen to be among the most cherished, though in many cases the role of fermentation in creating them is not widely understood. But coffee, chocolate, vanilla, bread, cheese, wine and beer, yogurt, ketchup and most other condiments, vinegar, soy sauce, miso, certain teas, corned beef and pastrami, prosciutto and salami—all depend on fermentation.

  Basically, it’s all the really good stuff.

  I suspect people in other cultures feel much the same way about their fermented foods, rotten shark included. Fermented foods are typically both strongly flavored and strongly prized in their cultures. This suggests that there may be a microbiology of desire at work in these foods, the bacteria and fungi having been selected over time for their ability to produce the flavors people find most compelling. Put another way, the microbes that could induce us to care for their cultures, as in a long-maintained sourdough starter or cheese culture, were the ones that prospered and survived. They travel with us through history, in a dance of biocultural symbiosis. As with L. sanfranciscensis, the bacteria found exclusively in sourdough cultures, some of the microbial strains found in fermented foods appear to live nowhere else—those foods have become their exclusive ecological niche. The microbes depend for their survival on a continuing human desire for the flavors they produce—one kind of culture upholding the other.

  Ten years ago, a retired Cornell microbiologist and fermentation expert by the name of K. H. Steinkraus conducted a global survey of fermented food products, organized by type. Here is a very small sample of what he found:

  LACTIC-ACID FERMENTS: sauerkraut, olives, pickled vegetables, Chinese hum choy, Malaysian tempoyak, Korean kimchi, Russian kefir, Indian dahi, Middle Eastern yogurts, Egyptian laban rayeb and laban zeer, Malaysian tairu, Western cheeses, Egyptian kishk, Greek trahanas and Turkish tarhanas, Mexican pozole, Ghanaian kenkey, Nigerian gari, Philippine balao balao and burong dalag, sourdough bread, Sri Lankan hoppers, Indian idli, dhokla, and khaman, Ethiopian injera, Sudanese kisra, Philippine puto, Western sausages, and Thai nham.

  ALKALINE FERMENTS: Nigerian dawadawa, Ivory Coast soumbara, African iru, ogiri, Indian kenima, Japane
se natto, Thai thua nao …

  On and on it goes, through the savory amino-acid ferments (soy sauce, fish sauce, ketchup); the fermented vegetable proteins (tempeh and ontjom); the acetic-acid ferments (vinegar, kombucha, nata de coco); and of course the numberless alcoholic ferments practiced in almost every culture (preconquest Australia and North America are thought to be the rule-proving exceptions), including South American Indian chicha, Egyptian bouza, Ethiopian tej, Kenyan busaa, Chinese lao-chao, and Japanese rice wine. To read Steinkraus’s vast exotic catalog is to begin to appreciate the deep links between human and microbial cultural diversity, and how through history each has fed and so sustained the other. To read him is also to worry about the survival of this biocultural diversity, since the industrialization of the world’s food strongly favors both homogenization and sterilization.

  Important as fermentation has been to human culture, we can’t take credit for inventing it. It is, like fire, a natural process, nature’s primary way of breaking down organic matter and recycling energy. Without it, as Steinkraus points out, “the earth would be a gigantic, permanent waste dump”—the dead would pile up and there would be no food for the living. Humans are also not the only animal that has learned to exploit fermentation for its own purposes: Think of the squirrel burying acorns (a kind of pit fermentation) or the bird souring seeds in its craw. Some animals also enjoy one of the most important by-products of fermentation: alcohol. And though few animals can be said to actually make alcohol (though it’s been reported that monkeys in eastern China will hoard flowers and fruits and patiently wait days for the cocktail to ferment before imbibing), some have it prepared for them by plants. The pen-tailed tree shrew (Ptilocercus lowii) of Malaysia enjoys a daily nip, drinking from a reservoir of alcohol prepared for its enjoyment by the bertram palm (Eugeissona tristis) in “specialized flower buds that harbor a fermenting yeast community.” The palm serves wine to the shrew that, in exchange for this kindness, pollinates the palm in the course of his barhopping through the jungle. Plant, animal, and yeast all benefit from this clever coevolutionary arrangement.