A Seasonal Practice of Fermentation

I GREW UP EATING SAUERKRAUT on street vendor hotdogs and loved it as a salty, sour, juicy condiment. Little did I know how important sauerkraut was as a survival food, enabling people in temperate climates with long winters to survive by providing them with a stable and reliable source of vitamin C. Yet I vaguely understood that sauerkraut had something to do with preserving cabbage and found a recipe in the cookbook ubiquitous in twentieth-century American kitchens: The Joy of Cooking. I couldn’t quite believe how straightforward the process was: Shred cabbage; lightly salt and gently massage the cabbage until it gets juicy; add seasonings if desired; then stuff the juicy salted cabbage into a crock or jars until it is submerged under its own juices; and wait while bacteria on the cabbage ferment carbohydrates into acids, which preserve it and protect it from pathogens.

Once I made that first batch of sauerkraut, I started experimenting and learned that I could ferment almost any firm vegetable or combination of firm vegetables in the same way; I could do it with less salt or more; I could shred finely, chop coarsely, or even leave vegetables whole; and I could season the vegetables any way I like. Since that first batch more than thirty years ago, I’ve had kraut going continuously and eaten it with almost every meal (even breakfast).

Wherever you live, and wherever your ancestors came from, fermentation is part of your cultural legacy; it’s as integral to how people everywhere use food as cooking and drying. Yet most of us have become removed from the cycles of growing foods and fearful of traditional processes such as fermentation that transform them. Do not let the “war on bacteria” scare you into believing that fermentation requires microscopes, laboratories, and specialized knowledge! Disparate fermentation processes were developed hundreds and thousands of years ago, with tools much more limited than those found in any contemporary kitchen. Consider this an invitation to celebrate the seasons by developing an annual fermentation practice in your kitchen.

WHERE I LIVE IN TENNESSEE, early spring brings tender young asparagus shoots and luscious juicy strawberries; in high summer you’ll find tomatoes and okra; and in autumn, hearty root vegetables. Though our globalized economy has promised transcendence from the limitations of geography and season—for instance, tomatoes available on demand, all year round—it cannot alter the inherent specificity of food production: what grows where, and when. Fermentation has been used for ages as a strategy for preserving seasonal abundance, catching foods at their ripest and most flavorful, so they can be enjoyed throughout the year.

Wine, for example, is fermented from fresh, ripe grapes and is generally made near where the grapes are grown. There is great variability from place to place, and season to season, in terms of soil, topography, and climate, which affects the growth and specific qualities of the grapes, as well as the microorganisms and conditions of fermentation. After the fermentation, wine can be aged and stored for long periods, but it is not something that can be made at any time. The same can be said for cider fermented from pressed apples, or any fruit-based alcohol. (In contrast, beer and other alcohol based upon grains—which are dry at harvest and can be stored for many months—can be fermented later, as needed.)

Many ferments are little known beyond the places where they are made. In Colombia, I tried a fizzy, delicious lightly fermented pineapple beverage called guarapo de piña, made by a man named Pacho, who belongs to an Indigenous Amazon group called the Matapi. He demonstrated how he makes the guarapo, and it is deceptively simple. Pacho grates ripe pineapples (skin and all), and lets the mash spontaneously ferment, meaning it ferments without added starters or intervention, driven by yeasts and bacteria indigenous to the pineapple itself. The fermentation requires just a day or two in the tropical heat, then Pacho strains the liquid and serves it. Guarapo de piña requires an abundance of pineapples, and it is made only where they grow and in the season when they are most abundant. Interestingly, in the Matapi culture guarapo de piña plays an important role in an annual ceremony marking the passage of the seasons and celebrating reciprocity with other life-forms. For days, participants dance and sing, foregoing all food and beverage except for guarapo de piña. As my Colombian host Esteban Yepes Montoya explained it to me, this brings them into a trance state, in which they “surrender to the here and now of the season” and “bow to the sacred essence of the pineapple.”

Another approach I’ve encountered for fermenting pineapples is perhaps more suitable for those of us living far from where pineapples grow: Mexican tepache, made from the skins and cores, the parts typically discarded when you eat a pineapple. Tepache exemplifies the potential to apply fermentation as a strategy to reduce and make use of food waste. Flavor, sugar, and acidity in the pineapple flesh that is inevitably cut away with the skin are infused into a sugar-water solution, as microbes in the skin begin to ferment it. Tepache is pretty straightforward to make and takes just a few days, so try it the next time you eat a pineapple!

GROWING UP IN NEW YORK CITY, the fermented food I loved as a kid was pickles—fermented cucumbers—though I couldn’t have told you back then that they were fermented. My grandparents and great-grandparents came to New York from Belarus and Lithuania, and the pickles that my family ate (not homemade but bought from a delicatessen) were the Eastern European style: cucumbers fermented with garlic and dill. We knew these pickles as “sour” or “half-sour,” depending on the intensity of their acidity, which I later came to understand as an expression of time. The longer the cucumbers ferment, the more lactic acid is produced.

It turns out that cucumbers can be among the most challenging vegetables to ferment. Cucumbers and other watery hot-weather vegetables, such as summer squash, have high concentrations of enzymes that break down the pectin that makes vegetables crispy and crunchy. Many of the fermentation traditions used to preserve cucumbers come from places with relatively mild summers, like Belarus and Lithuania. In hot environments, it’s easy for fermented cucumbers to get soft and mushy; and nobody likes a mushy pickle! I’ve learned a number of techniques to help keep pickles crunchy, and I’m happy to report that despite the intensely hot summers where I live in Tennessee, I’ve learned to make consistently crunchy pickles.

Most other vegetables are easier to ferment than cucumbers, and pretty much all vegetable fermentation traditions are seasonal. My first fermentation experiences were driven by the realities of the garden. When I started gardening after I moved from New York City to rural Tennessee, I was such a naïve city kid that I hadn’t considered that in a garden, all the cabbages or all the radishes are ready at about the same time. Faced with a glorious abundance of cabbage the first year I was gardening, I turned to making sauerkraut, using fermentation as a strategy to preserve the harvest and extend the season.

While I continue to enjoy traditional cabbage kraut, I’ve come to make my biggest batches of kraut from daikon radishes, which a farmer friend grows as a soil-improving cover crop. Each autumn, in late October, I drive a pick-up truck to his farm and fill up the truck with hundreds of pounds of daikons, along with some cabbages. Friends help scrub, chop, and salt the veggies, and then pack them into a hundred-liter vessel. We enjoy radish kraut all autumn, winter, spring, and into the early summer.

As with other vegetables, there are actually many different ways you can ferment a daikon. You can do it Korean style, as kimchi. You can do it Japanese style, as takuan, nuka, or other types of tsukemono. You can do it Sichuan style, as pao-cai. Or you can do it Taiwanese style, as cai bo, aged for years or even decades. (I tried some that had been aged for more than forty years!) Or, you can use your imagination and create your own innovative style of pickling. My Tasmanian friend Adam James used an abundance of turmeric to create a turmeric-based paste which he uses as a perpetual pickling medium, and daikon pickled in that turn bright yellow (on the outside). All of which is to say, there is no limit to the possible approaches to fermenting! Do not be afraid to experiment.

And it’s not only fruits and vegetables that give rise to seasonal fermentation traditions. Many of Korean cuisine’s most distinctive flavors come from jangs, seasonings fermented using meju, a starter which is itself fermented from a block of soybeans. The whole process begins with the soybean harvest, typically in October. The beans are cleaned, soaked, cooked until soft, and then mashed and pressed into brick-like blocks. The first few days of the fermentation, while the blocks are very moist, they are kept on a mat of rice straw in a heated space and turned periodically so that every side of each block comes into contact with the straw, an important source of bacteria and fungi, as well as with the air, so the blocks become dry enough to hang. During this initial stage, the fermentation is dominated by bacteria known as Bacillus.

After a few days in this warm environment, the exteriors of the blocks become dry enough that they can be handled. They are then tied and hung in an open-air environment where they continue to develop in fluctuating temperatures, protected from rain. The meju-maker I visited, Bong Rok Oh, hung his meju in an open-ended plastic-covered hoop house. Here, diverse molds flourish, typically dominated by the genus Aspergillus. According to Mr. Oh, the more diverse the fungi, the more complex the flavor profile of the meju. He hangs the blocks of meju in the hoop house for two to three months and begins to harvest them after the lunar New Year in February.

Meju is not eaten as a food; rather, it is the starting point for doenjang, ganjang, gochujang, and other jangs, which are used as building blocks of flavor in Korean cuisine. I’m making my first batches of doenjang (soy sauce) and ganjang (soy paste) from a block of meju that I was gifted by Mr. Oh. The two products are made in tandem, beginning with a single process: covering the meju with a salty brine. Mr. Oh was vague about his salt proportions, except to say that due to warmer temperatures, he had been forced to increase the salt in recent years, as salt inhibits putrefying bacteria and other undesirable organisms that are more prolific at warmer temperatures. Climate change impacts everything in fermentation, from what plants thrive where, to the dynamics of microbial growth and accordingly to details such as salt proportions and timing. I mixed my brine at 18 percent salt by weight (180 grams salt per liter of water)—extremely salty—knowing that the salt would be diluted by the mass of the meju. I used enough brine to allow the meju to float in it.

The meju absorbs brine, softens, and gradually breaks apart into the brine. Mr. Oh’s fermentation vessels were stored outdoors, with glass covers to allow for sun exposure while still protecting them from rain. I stored my crock in the house but brought it outside and opened it on sunny days to give it sun exposure, stirring it regularly. The meju is fermented in the brine for about three months, then the liquid is strained and pressed from the solids, and the two distinct products begin to diverge: The liquid is further fermented to become ganjang, and the solids are further fermented to become doenjang. These final fermentations take a minimum of one year, but ideally several. One fermentation master I met in Korea has a vessel full of 129-year-old soy sauce, and he adds a little of that to each of his contemporary batches.

An inheritance like this really highlights the generational continuity of seasonal food preservation traditions, which sadly few of us have carried on. Yet, if we are to be more connected to the lands where we live, and to the plants, animals, and ancestral processes that enable us to survive and thrive, we must find ways to reestablish these seasonal traditions. I call myself a fermentation revivalist, because my work aims to empower people to revive fermentation as a living tradition in our homes and communities.

All around the world, fermentation is an essential part of how people make effective use of food resources. It is both a strategy and a celebration, engaging us more intimately with plants, invisible forces such as bacteria, and other relationships that connect us, through the rich transformations of the seasons, to the Earth. Incorporating a simple fermentation practice into your kitchen routine will enable you to produce foods or drinks that you can enjoy and share with others, inviting them to join in these ancient processes, which are still as important and relevant as ever.