Vegetable Fermentation Further Simplified

Excerpted from The Revolution Will Not Be Microwaved

A head of cabbage forgotten on an obscure shelf of your pantry will not spontaneously transform itself into sauerkraut. Vegetables left exposed to air start to grow molds, and if left long enough, those molds can reduce a head of cabbage to a puddle of slime, bearing no resemblance whatsoever to crunchy, delicious, and aromatic sauerkraut.

The simple key to successful vegetable fermentation is to make sure your vegetables are submerged in liquid. That’s it, the big secret. Usually the liquid is salty water, also known as brine, but fermentation can be done without salt, or with other liquids, such as wine or whey. Typically, when fresh vegetables are chopped or grated in preparation for fermentation—which creates greater surface area—salting pulls out the vegetable juices via osmosis, and pounding or tamping the vegetables breaks down cell walls to further release juices, so no additional water is required. However, if the vegetables have lost moisture during long storage, occasionally some water is needed; if brine hasn’t risen to submerge the weighted vegetables by the following day, add a little water. In the case of vegetables left whole (cabbage heads, cucumbers, green tomatoes, string beans, okra, zucchini, eggplant, peppers—try anything), the vegetables should be submerged in brine.

The huge variety of vegetable ferments you can create all exist along the spectrum from shredded and salted to whole and submerged in a brine. Sometimes you use elements of each style, as in kimchi recipes that call for soaking vegetables in a brine to soften them and leach out bitter flavors, then pouring off excess brine and mixing in spices. In some cases the liquid is what we’re after, flavored by the vegetables and fermentation.

Pretty much any vegetable can be fermented. Use what is abundantly available and be bold in your experimentation. Seaweeds are a wonderful addition to ferments, as are fruits, though mostly fruit ferments go through their process very quickly. I’ve even made delicious sauerkraut with mashed potatoes layered in with the salted cabbage, as well as kimchi with sticky rice layers. The sharp fermented starches are delicious. The spicing of vegetable ferments is quite varied, too. Kimchi typically includes red chili peppers, garlic, ginger, and scallions. Sauerkraut might include caraway seeds (my favorite), juniper berries, apples, or cranberries. New York–style sour pickles are spiced with dill, garlic, and sometimes hot peppers. To keep cucumbers crunchy, add to the brine some grape leaves or leaves of horseradish, oak, currant, or cherry.

How much salt do you use? Traditionally vegetables have been fermented with lots of salt. In addition to pulling water from the vegetables, salt hardens pectins in the vegetables, rendering them crunchier, and discourages the growth of bacteria other than lactobacilli. By inhibiting competing bacteria, salt enables the vegetables to ferment and to be stored for longer periods of time. Since preservation has historically been one of the important motivations for fermentation, ferments have tended to be quite salty. But for health-conscious people interested primarily in flavor and nutrition, less salt can be better. Salt lightly, to taste. It is easier to add salt than to take it away, but if you oversalt, you can dilute by adding water and/or more vegetables. There is no magic proportion of salt the process requires—it’s just personal preference. As a starting point, try 3 tablespoons of salt per 5 pound of vegetables. More salt will slow the fermentation process; less (or none) will speed it up. Ferments with less salt may be more prone to surface molds. You can leave out the salt or use various mineral-rich substitutes such as celery juice (my favorite salt-free variation) or seaweed. Just be sure the vegetables are submerged in the liquid.

Some people promote the idea that salt-free sauerkrauts contain more beneficial organisms than salted krauts. I don’t believe that. The most specific beneficial bacteria we’re after, Lactobacillus, is salt-tolerant and abundantly present even in salty krauts; arguably, salt-free ferments are more biodiverse, but this diversity often results in mushy textures. Though it is possible to ferment vegetables without salt, a little salt results in far superior flavor and texture—and just as much beneficial bacteria. So again, salt to taste.

What kind of vessel should you use to hold your ferment? Avoid metal, as salt and the acids created by fermentation will corrode it. Heavy ceramic cylindrical crocks are the ideal fermentation vessels, though they can be hard to find and expensive. Glass containers work well, especially those with a cylindrical shape or with a wide mouth, and so do nesting bowls. Crock pots with ceramic interiors make effective fermentation vessels and can often be found in thrift stores. In a pinch, you can use plastic, but even food-grade plastics leach toxic chemicals.

The reason a cylindrical shape is desirable is for ease of weighting down the fermenting vegetables to keep them submerged rather than floating to the top. I generally use a plate that just fits inside the vessel, weighted down by a full jug of water, and I drape a cloth over the top of the vessel to protect against flies. I call this the “open-crock” method. Containers in other shapes can work with improvisation, or you can manually press the vegetables to submerge them in the liquid.

If the vegetables float to the top and remain exposed to air, they are likely to develop mold. Sometimes, especially in hot weather, your ferment may develop a film of white mold on its surface. This is very common and will not hurt you or the kraut. Scrape off the mold as best you can, don’t worry about particles that mix into the vegetables, and enjoy the delicious ferment beneath. Specially designed Harsch crocks eliminate this problem by creating an oxygen-free airspace around the ferment. These German crocks are elegant but expensive. Another way to avoid mold is by weighting the ferment in the vessel with water contained in a double layer of plastic bags. The water will spread to cover the entire surface, protecting it from aerobic surface molds. The downside of this method, of course, is that your food comes into prolonged contact with plastic, which leaches chemicals into the food. I prefer to use the open-crock method and remove mold as necessary.

Whatever type of vessel you use, pack the vegetables into it with some force (unless they are whole), in order to break down cell walls and release juices. I use a blunt wooden tamping tool. You can improvise with a piece of wood or your fist, or you can manually massage and squeeze the vegetables, as described in the recipe for massaged kale (see page 185). Once the vegetables are weighted down, the salt will continue to pull moisture from the vegetables for many hours yet. If, by the following day, the vegetables are not submerged, add a little water.

How long do you ferment the vegetables? I wish I had an easy answer to this question. “Ferment until ripe,” many recipes advise, but ultimately you will have to decide when it is ripe. Sour flavor—from lactic acid—develops over time. Longer fermentation translates to tangier flavor. This happens more quickly in warm temperatures than in cool ones. If you start your ferment at harvest time, in the autumn, as temperatures are dropping, it can ferment for six months or longer. This is how people survived before refrigeration and globalized food. Many people, however, prefer the flavor of a mild ferment to that of a strongly acidic one. When you are first experimenting, taste your ferments early and often. Serve some after three days, then three days later, and again three days after that. Familiarize yourself with the spectrum of flavors that fermentation can create and see what you like.

Making Sauerkraut

Sandor Ellix Katz, the creator of this site, has earned the nickname “Sandorkraut” for his love of sauerkraut. This is Sandorkaut’s easy sauerkraut recipe from his book Wild Fermentation: The Flavor, Nutrition, and Craft of Live-Culture Foods (Chelsea Green, 2003).

Timeframe: 1-4 weeks (or more)

Special Equipment:

  • Ceramic crock or food-grade plastic bucket, one-gallon capacity or greater
  • Plate that fits inside crock or bucket
  • One-gallon jug filled with water (or a scrubbed and boiled rock)
  • Cloth cover (like a pillowcase or towel)

Ingredients (for 1 gallon):

  • 5 pounds cabbage
  • 3 tablespoons sea salt

Process:

  1. Chop or grate cabbage, finely or coarsely, with or without hearts, however you like it. I love to mix green and red cabbage to end up with bright pink kraut. Place cabbage in a large bowl as you chop it.
  2. Sprinkle salt on the cabbage as you go. The salt pulls water out of the cabbage (through osmosis), and this creates the brine in which the cabbage can ferment and sour without rotting. The salt also has the effect of keeping the cabbage crunchy, by inhibiting organisms and enzymes that soften it. 3 tablespoons of salt is a rough guideline for 5 pounds of cabbage. I never measure the salt; I just shake some on after I chop up each cabbage. I use more salt in summer, less in winter.
  3. Add other vegetables. Grate carrots for a coleslaw-like kraut. Other vegetables I’ve added include onions, garlic, seaweed, greens, Brussels sprouts, small whole heads of cabbage, turnips, beets, and burdock roots. You can also add fruits (apples, whole or sliced, are classic), and herbs and spices (caraway seeds, dill seeds, celery seeds, and juniper berries are classic, but anything you like will work). Experiment.
  4. Mix ingredients together and pack into crock. Pack just a bit into the crock at a time and tamp it down hard using your fists or any (other) sturdy kitchen implement. The tamping packs the kraut tight in the crock and helps force water out of the cabbage.
  5. Cover kraut with a plate or some other lid that fits snugly inside the crock. Place a clean weight (a glass jug filled with water) on the cover. This weight is to force water out of the cabbage and then keep the cabbage submerged under the brine. Cover the whole thing with a cloth to keep dust and flies out.
  6. Press down on the weight to add pressure to the cabbage and help force water out of it. Continue doing this periodically (as often as you think of it, every few hours), until the brine rises above the cover. This can take up to about 24 hours, as the salt draws water out of the cabbage slowly. Some cabbage, particularly if it is old, simply contains less water. If the brine does not rise above the plate level by the next day, add enough salt water to bring the brine level above the plate. Add about a teaspoon of salt to a cup of water and stir until it’s completely dissolved.
  7. Leave the crock to ferment. I generally store the crock in an unobtrusive corner of the kitchen where I won’t forget about it, but where it won’t be in anybody’s way. You could also store it in a cool basement if you want a slower fermentation that will preserve for longer.
  8. Check the kraut every day or two. The volume reduces as the fermentation proceeds. Sometimes mold appears on the surface. Many books refer to this mold as “scum,” but I prefer to think of it as a bloom. Skim what you can off of the surface; it will break up and you will probably not be able to remove all of it. Don’t worry about this. It’s just a surface phenomenon, a result of contact with the air. The kraut itself is under the anaerobic protection of the brine. Rinse off the plate and the weight. Taste the kraut. Generally it starts to be tangy after a few days, and the taste gets stronger as time passes. In the cool temperatures of a cellar in winter, kraut can keep improving for months and months. In the summer or in a heated room, its life cycle is more rapid. Eventually it becomes soft and the flavor turns less pleasant.
  9. Enjoy. I generally scoop out a bowl- or jarful at a time and keep it in the fridge. I start when the kraut is young and enjoy its evolving flavor over the course of a few weeks. Try the sauerkraut juice that will be left in the bowl after the kraut is eaten. Sauerkraut juice is a rare delicacy and unparalleled digestive tonic. Each time you scoop some kraut out of the crock, you have to repack it carefully. Make sure the kraut is packed tight in the crock, the surface is level, and the cover and weight are clean. Sometimes brine evaporates, so if the kraut is not submerged below brine just add salted water as necessary. Some people preserve kraut by canning and heat-processing it. This can be done; but so much of the power of sauerkraut is its aliveness that I wonder: Why kill it?
  10. Develop a rhythm. I try to start a new batch before the previous batch runs out. I remove the remaining kraut from the crock, repack it with fresh salted cabbage, then pour the old kraut and its juices over the new kraut. This gives the new batch a boost with an active culture starter.