As the example of alcohol suggests, the uses of fermentation extend well beyond preservation, though it seems likely that preservation was humanity’s original impetus for mastering the process. (Alcohol—a strong antiseptic—is itself an important preservative.) Archaeologists believe that, until there were reliable methods to preserve food, humanity could not have moved from hunting and gathering to a more settled, agricultural pattern of life. Fermentation (along with other preservation techniques, such as salting, smoking, and drying) provided a critical measure of food security, allowing agriculturists to survive the long months between harvests and to withstand the inevitable crop failures. Though, as I would discover when I started to brew beer (because brewers can always be counted on to mention it), there is a school of archaeological thought that contends that the reason humanity turned to agriculture was to secure a more reliable supply of alcohol, not food. Either way, the mastery of fermentation and the advent of agriculture (and civilization in turn) appear to go hand in hand.
As so often happens, the original purpose of an invention or adaptation doesn’t turn out to be the ultimate or even highest use to which it is put. Humans soon recognized that fermenting various foodstuffs did a lot more than extend their shelf life, important as that was. Fermenting the juices of fruit not only sterilized the beverage, but also turned it into a powerful intoxicant. A great many foodstuffs become significantly more nutritious after fermentation. In some cases, the process creates entirely new nutrients—several B vitamins are synthesized in the fermentation of beer, soy sauce, and various grains. Natto, the slimy odiferous ferment of soybeans beloved by the Japanese, produces a unique therapeutic compound called nattokinase. Many grain ferments yield important amino acids, such as lysine. Sauerkraut contains breakdown products believed to fight cancer, including isothiocyanates such as sulforaphane. (It also contains goodly amounts of vitamin C: Captain Cook kept his crew free from scurvy during a twenty-seven-month journey by forcing them to eat sauerkraut.) As I learned when I was baking bread, the fermentation process renders grain more nutritious by breaking down chemical compounds that interfere with nutrient absorption, such as phytate. Fermentation also breaks down toxic compounds in certain plants. That shark I tasted in Iceland? It would have sickened me (well, even more than it did) had it not been fermented. This particular species of shark has no kidneys, so toxic levels of uric acid accumulate in its flesh; the fermentation renders it harmless. Oxalic acid, another antinutrient, found in certain vegetables, is also broken down during fermentation.
To ferment food is to predigest it, in effect, breaking long chains of proteins, fats, and carbohydrates our bodies might not be able to make good use of into simpler, safer compounds that they can. Think of the kraut crock as a burbling auxiliary stomach, doing much of the work of digestion before your body has to. As with cooking, it offers your body an energy savings. Unlike cooking, however, the energy required to ferment food does not need to come from burning wood or fossil fuel. It is self-generated, by the metabolism of microbes breaking down the substrate. Fermentation can easily be done off the grid, a quality that commends it to the enviros, anarchists, and peak-oil types who help make up the subculture. “The historical bubble of refrigeration may not last,” Katz likes to point out. When that particular bubble bursts, you’re going to want to know people like Sandor Katz and microbes like L. plantarum.
Fermenting foods also intensifies their flavors, a particular boon to agricultural humans. The advent of agriculture dramatically narrowed the human diet, in many cases down to a small handful of bland staples, most of them carbohydrates. All the year long, fermented foods allowed people to enliven a monotonous diet with strong flavors, while supplementing it with vitamins, minerals, and phytochemicals that staple foods often lack.
People tend to feel very strongly about the flavors of fermentation, one way or the other. “Between fresh and rotten,” Katz has written, “there is a creative space in which some of the most compelling flavors arise.” In the same way that the process of ripening fruits imbues them with deeper, richer flavors and scents, many other foods acquire powerful new sensory qualities just as they begin to decompose. Why should this be? Perhaps for the same reason that our taste buds respond more strongly to simple sugars than to complex carbohydrates, or to amino acids rather than long protein chains. We’ve evolved specific taste receptors for these basic molecular building blocks (umami) and simple packets of energy (sweetness), so respond favorably to foods that have been broken down to those indispensable elements, whether by cooking or fermentation.
Yet many of the flavor molecules created by fermentation are not so simple or universal in their appeal. Could it be that, like ripening fruits, the microbes that decompose foods produce powerfully aromatic compounds for their own purposes? The reason fruits produce strong scents and flavors when ripe is to attract animals that can transport their seeds. The microbes that rot fruit or other foods also emit signaling chemicals. Some are designed to repel competitors. But others are attractants. Like the seeds of plants, fermentation microbes sometimes need help with transportation, especially after they’ve exhausted a food source. Some scientists believe that bacteria and fungi produce their own taxi-hailing scent compounds, in order to attract the insects and other animals they need to transport them to the next feast of putrefaction.
What’s curious is how culturally specific so many of the flavors of fermentation turn out to be. Unlike sweetness or umami, these are not the kinds of simple flavors humans are hardwired to like. To the contrary, these are “acquired tastes,” by which we mean that to enjoy them we often must overcome a hardwired aversion, something it usually takes the force of culture, and probably repeated exposure as a child, to achieve. The most common term children and adults alike will use to describe the fermented foods of another culture is some variation on the word “rotten.” A wrinkle of the nose is how we react to both rottenness and foreignness. Many of these foods occupy a biological frontier—on the edge of decomposition—that turns out to be a well-patrolled cultural frontier as well.
Considered as a method, or set of methods, for food processing—for turning the stuff of nature into safe, nutritious, durable, and delicious things to eat—the ancient arts of fermentation have yet to be improved on. For what has modern food science given us that can compare? Vacuum-sealed cans. Frozen foods. Microwavable entrées. Mock meats made from soy. Baby formula. Irradiated food. Vitamin-fortified breakfast cereal in colors. Energy bars. Powdered Jell-O. Marshmallow fluff. Cryovacking. Freeze-drying. Artificial sweeteners. Artificial sweeteners with fiber. Margarine. High-fructose corn syrup. Low-fat and no-fat cheese. Quorn. Cake mix. Frozen peanut butter and jelly sandwiches. The countless simulations of real foods and real flavors that line the center aisles of the supermarket. Stack any of these inventions up against such achievements as wine or beer, against cheese, against chocolate, soy sauce, coffee, yogurt, cured olives, vinegar, pickled vegetables of all kinds, cured meats, and the conclusion is inescapable: Thousands of years on, we still haven’t discovered techniques for processing food as powerful, versatile, safe, or nutritious as microbial fermentation.
And yet these latter-day industrial methods of food preservation and processing have pushed most live-culture foods out of our diet. Yogurt is the exception that proves the rule, which is that very few of our foods any longer contain living bacteria or fungi. Vegetables are far more likely to be canned or frozen (or eaten fresh) than pickled. Meats are cured with chemicals rather than microbes and salt. Bread is still leavened with yeast, but seldom with a wild culture. Even the sauerkraut and kimchi are now pasteurized and vacuum packed—their cultures killed off long before the jar hits the supe
rmarket shelf. These days most pickles are no longer truly pickled: They’re soured with pasteurized vinegar, no lactobacilli involved. Open virtually any modern recipe book for putting up or pickling food and you will be hard pressed to find a recipe for lactofermentation: What once was pickling has been reduced to marinating in vinegar. And though it’s true that vinegar is itself the product of fermentation, it is frequently pasteurized, a finished, lifeless product, and far too acidic to support most live cultures.
The modern food industry has a problem with bacteria, which it works assiduously to expunge from everything it sells, except for the yogurt. Wild fermentation is probably a little too wild for the supermarket, which has become yet another sterile battlefield in the war on bacteria. Worries about food safety are very real, of course, which is why it’s probably easier for the industry to stand staunchly behind Pasteur than to try to tell a more nuanced story about good and bad bugs in your food. With the result that live-culture foods, which used to make up a large part of the human diet, have been relegated to the handful of artisanal producers and do-it-yourselfers signing up for Sandor Katz’s “cultural revival.”
This might not matter to much of anyone but a confirmed Slow Foodie, eager to save and sample endangered food traditions, except for one notable fact: Medical researchers are coming around to the startling conclusion that, in order to be healthy, people need more exposure to microbes, not less; and that one of the problems with the so-called Western diet—besides all the refined carbohydrates and fats and novel chemicals in it—is the absence from it of live-culture foods. The theory is that these foods have a crucial role to play in nourishing the vast community of microbes living inside us, which in turn plays a much larger role in our overall health and well-being than we ever realized. Bacteria-free food may be making us sick.
My first solo expedition into the wilds of the post-Pasteurian world came last summer, when I tested a few of Sandor Katz’s pickling recipes at home. I decided to begin my education with vegetable ferments because they seemed the easiest and, which is important, the safest. No less an authority than Steinkraus had written that the safety record of fermented vegetables was very good even when “the foods are manufactured by people without training in microbiology or chemistry in unhygienic, contaminated environments.” (That would be me.) One USDA scientist went so far as to claim that there has never been a documented case of food-borne illness from eating fermented vegetables.
Suitably reassured, I bought a case of quart-sized Mason jars at the hardware store. I did not sterilize them, just rinsed them out with some hot tap water. I also ordered online a 7.5-liter German sauerkraut crock. The perimeter of this ceramic crock has a deep circular well into which the lid fits; filling this moat with an inch or two of water creates an airlock that prevents oxygen from getting in while allowing the carbon dioxide emitted during fermentation to bubble out. Note: I discovered when it arrived that 7.5 liters is a much bigger crock than anyone needs, unless you’re planning to feed a small German village. It took no fewer than six large heads of cabbage to fill my crock. That represents easily a few years’ worth of sauerkraut in my house.
Fermentation vessels at the ready, I paid a visit to the farmers’ market and bought a bunch of pickle-able vegetables: cabbages of course (both Napa and regular), cucumbers, carrots, cauliflower, sweet and hot peppers, beets, radishes, turnips, etc. At the supermarket, I loaded up on bulbs of garlic, ginger roots, and various pickling spices—juniper berries; dill, coriander, and caraway seeds; star anise; and black pepper—and a big box of sea salt.
According to Katz, there are two basic approaches to fermenting vegetables: leafy ones, like cabbage, are best fermented in their own juices, whereas others require the addition of a brine to keep them fully submerged in liquid. The saltiness of the brine is a matter of personal preference, but several of the sources I consulted recommended 5 percent, so I started with that. I dissolved the salt in a pot of hot water (roughly an ounce of salt for every three cups of water), to which I added various combinations of spices.* While the mixture cooled on the stovetop, I packed the vegetables into a Mason jar (usually with cloves of garlic, sometimes with sliced ginger as well) and then poured the brine over them. Katz had said the vegetables should be completely submerged, but invariably some insist on floating to the top, exposing themselves to oxygen—and the possibility of rot. I tried a variety of tricks to force them back underwater, including a saucer, some Ping-Pong balls, a plastic bag filled with pebbles, and some weighted grape leaves. I had read that grape leaves, which contain tannins, help keep the vegetables crisp by suppressing certain fungi. (Oak, cherry, or horseradish leaves, do the same thing.)
The procedure for making sauerkraut is slightly more involved. After quartering the cabbages and cutting out their hard cores, you can either shred the resulting chunks on a mandoline or cut them with a knife. I found shredding made life easier and produced more liquid more quickly than cutting with a sharp knife, probably because the knife doesn’t leave as much surface area for the salt to go to work on. Put the shredded cabbage in the biggest bowl you own, sprinkling as you go with salt, and then, with all your fingers, press and squeeze and generally bruise the cabbage leaves without mercy until your hands begin to cramp. Now put something heavy on top of the heap to force the water from the leaves—a second bowl full of rocks will work, or use the crock itself. Within twenty minutes or so, the shredded cabbage will be awash in cabbage juice, magically beckoned out of the leaves by the salt.
Pack handfuls of shredded cabbage, with its liquid, into the crock as tightly as you can, a layer at a time. Add garlic and spices (for my first batch I used juniper berries, dill, and coriander) after each layer, pushing the mixture down and squeezing out air as you work. If you’re using a sauerkraut crock, it probably came with a heavy inner lid made from fired clay or brick. Place this on top of the kraut and force it down until liquid rises high enough to cover everything. Then fit the outer lid into the lip and fill with water to create the seal. Keep the crock in the kitchen, where you can watch (and listen to) it for the first few days.
The procedure for making kimchi is either only slightly different, according to Sandor Katz and other American fermentos I consulted, or substantially different, according to actual Korean people. Aware of, but unperturbed by, the authenticity issue, Sandor calls his version “kraut-chi,” and that’s what I tried to make first. With a sharp knife, I cut heads of Napa cabbage into one-inch rounds. In addition to the salt, I added enough red chili powder to turn the cabbage red, along with as much garlic and ginger as I could stand to grate, and some fresh hot peppers. I also added slices of daikon radish and apple, as well as a bunch of spring onions. You can pack this into a kraut crock or an ordinary glass jar, making sure there’s some way for gases to escape. But I found that an airlock is not critical when making kimchi, probably because the peppers and garlic, both vigorously antimicrobial, keep fungi from getting established. (In Korea, as I would learn, kimchi is made by soaking Napa cabbage in a brine overnight; the heads are then rinsed before the leaves are individually rubbed with a paste of ground-up red peppers, garlic, and ginger.)
Within a few days, and straight through that fall, my kitchen counters were lined with an assortment of jars, bowls, bottles, and crocks of various fermenting vegetables. In addition to the sauerkraut and kimchi, I pickled cauliflower, carrots, cucumbers, chard stems, beets, ramp bulbs, garlic cloves, turnips, and radishes. As the colors of the vegetables grew more vivid in their brines, and the brines themselves took on the pigments of the vegetables, the jars and bottles grew more exotically beautiful. I was reminded of tanks of tropical fish. And just like fish tanks, some of the crocks b
ubbled. Three days after filling it, the big crock of kraut began to stir, every few minutes emitting a bubble of gas with a resonant cartoony-sounding baritone burble. Fermentation had begun, which meant it was time to move the crock to a cooler location in the basement, so that it wouldn’t proceed too fast.
So what was going on in there, deep within those thick brown ceramic walls? This sort of microbial cooking is invisible and gradual—not much drama to observe, apart from the occasional bubble or bulging of lids on the Mason jars. Yet there was a kind of drama unfolding in these containers, a microscaled drama I had set in motion simply by shredding and salting some dead plant parts. In doing so, I had created a very particular environment—an ecological niche that was in the process of being colonized by new life. (In this respect, too, the crock resembled a fish tank—only this was a microbe tank.) But what was uncanny was how the niche had populated itself—spontaneously. I had done nothing to inoculate it,* and yet on the evidence of the increasingly insistent bubbling, the kraut was now very much alive. The necessary bacteria had been there from the start, dormant but lurking on the cabbage leaves, waiting patiently for conditions to be exactly right—wet, airless, saline, the leaves too badly wounded to keep them out—to set about their methodical work of destruction and creation.
Cooked: A Natural History of Transformation Page 31