Kimchee (also spelled Kimchi) is traditional Korean spiced fermented Napa cabbage, famous for being a great probiotic food and for being one of the cornerstones of Korean cuisine. There are other Kimchee instructables out there, but several things set this particular one apart:
- I've incorporated an optimization from the European sauerkraut making traditions into my method.
- I incorporated the Bay Area's favorite leafy green superfood, Lacinato kale (a.k.a. Tuscan kale or dinosaur kale), into my recipe.
- I include a primer on fermentation that gives you a nerd's-eye view of fermentation that will give you an understanding of what it is all about.
- I show you details about inexpensive but perfectly functional fermentation vessels that cost less than a tenth of what European style stoneware fermentation crocks cost.
- This recipe doesn't leave out the ingredients westerners might be squeamish about— fish sauce and tiny salted shrimp or krill. Although these ingredients are overwhelming when tasted by themselves, they are the secret to a great tasting savory kimchee. I'll explain why in the corresponding step.
- Many of the steps are taken in the first-person-shooter perspective, so you know what you'll be looking at when you actually put your hand to the task.
The secret to food preservation:
Make food inhospitable to microbial decomposers
Did you know that foods do not decompose without biological intervention? The food may oxidize or dry out or go stale (starch retrogradation), and some substances may be unstable and break down into a more stable form, but if you took food, sealed it in a totally sterile bell jar filled with an inert gas, and irradiated all the microbes to death, it would never rot. It would sit there like the 14 year old McDonald's burger, forever untouched by decomposition as we know it. This is because decomposition is not merely oxidation and dehydration; decomposition is carried out by decomposers—yeasts, bacteria, molds, worms, insects, or the digestion of some creature. The microbes that would gladly eat your food for you are everywhere; their spores are in the air, and they are often symbiotic with the produce that we buy, naturally occurring on the surfaces of the leaves and fruit. In the days before refrigeration, the options that we had for preserving food were fairly limited, and broadly speaking, they fall into several categories:
- Chilling: store the food where it is cool, such as a cellar or a zeer pot (non-electrical refrigerator). The cooler temperatures hinder the onset of decomposition long enough for you to eat your food first. (This is generally not very long without freezing cold temperatures.)
- Killing the microbes:
- Salting / curing: with enough salt, the food becomes osmotically hostile to any microbe. Salted fish, fruits, meats, and vegetables essentially resist microbial decomposition by dehydrating all the resident microbes to death.
- Drying: drying out a food can also be done simply by exposure to sun and dry air. This achieves the same outcome: the microbes present on the food and in the air find the dry food inhospitable, and either become dormant or die of dehydration.
- Smoking: smoking foods will impart chemicals from smoke that are naturally anti-microbial; this hinders any microbes from attacking the food from its surface.
- Candying: sugar, when used in sufficient concentration, will also make a food osmotically inhospitable to microbes. Jams, jellies, and preserves fall under this category.
- Acidifying or alkalizing: Vinegar can make a food too acidic for most microbial decomposers to survive, and is commonly used to pickle foods without direct fermentation, though most historic pickling methods produce the acid by bacterial fermentation. (Vinegar itself is a secondary fermentation product of wine or other alcoholic liquids.) Alternatively, some forms of this method of preservation use lye to make the food too alkaline for decomposers, such as the legendary Scandinavian lutefisk.
- Canning: Although canning as we know it is really pasteurization, and was not practiced in ancient times due to the inability to reliably seal a vessel against infiltration by microbes, canning is another low-tech way of preserving food that relies on killing all the resident microbes in a food by exposure to heat. Sealing the canning vessel prevents the infiltration of other microbes, thus preserving the food.
- Fermenting: fermentation is essentially selecting what microbe (or microbes) you want to take over your food, and using the preferred microbes' natural defenses to fend off unwanted microbes.
How fermentation preserves food:
One form of filth kills another form of filth
Fermentation is best described as human intervention into a three way microbial war for the purpose of preserving food and enhancing its flavor. These are the three major combatants in this microbial war:
- Yeast, which produce alcohol that kills bacteria and molds
- Bacteria, which produce acids that kill molds and yeast
- Molds, which produce digestive enzymes and antibiotics that kill yeast and bacteria
These three battle for supremacy over who gets to take over our food, and in the course of doing so, produce substances which fend off the colonization and growth of the others, particularly the decomposers. This microbial chemical warfare is memorably summarized by the observation that one form of filth kills another form of filth.  What we do when we ferment is to make alliances with the microbe of our choice by creating conditions favorable to that particular kind of microbe so that they can take over our food; in exchange for letting them utilize some of the calories in the food, we utilize their natural defenses to ward off unwanted microbes that would decompose the food or cause food poisoning.
In some forms of fermentation, such as Kombucha (fermented tea), we ally ourselves with two classes of microbes at the same time—bacteria and yeast. In others, such as Sake (Japanese rice wine), we switch sides midway through; in sake, mold is used to break down rice starch into fermentable sugars; then, the alliance with mold is broken as the moldy rice is mashed up to break up the mold structures; the mash subsequently liquefied and fermented with yeast, which convert the sugars into alcohol. For vinegar, yet another stage of fermentation is carried out where acetobacter bacteria are employed to convert alcohol (in low enough concentration that it won't kill bacteria) into acetic acid. In the case of rice wine vinegar, all three of the microbes are employed one after another. Many cured meats such as salami and cheeses such as brie are cured with penicillium mold, which colonize their outer surfaces and prevent the infiltration of harmful bacteria. Miso (fermented soy bean paste) is fermented with koji mold and preserved with salt. Sour cream and yogurt are fermented with various kinds of lactic acid bacteria and get their characteristic sourness from lactic acid and other flavorful acids.
In the case of kimchee, the fermentation is carried out by yeast and bacteria, with bacteria being the dominant player.
Fermentation for flavor and nutritional enhancement
In addition to fending off unwanted decomposers, fermentation has several great side effects, one of which is the enhancement of flavor. Consider what fermentation does to soy beans: soybeans and tofu are pretty bland, and are commonly used only as a substrate for sauces and other flavors, but once fermented, they become the basis of some of the most savory ingredients ever—miso, doenjang (Korean style fermented bean paste), and soy-sauce. Fermentation is also what gives bread and wine and beer their depth of flavor compared to their unfermented ingredients.
Fermentation also has the added benefit of up-converting carbohydrates into vitamins and increasing the nutritional density of many foods. Consider kombucha; the tea and the sugar used to brew kombucha have no nutritional value besides empty calories, but after fermentation, kombucha is a rich source of B vitamins. Cabbage becomes more digestible and also sees its vitamin content increased by the process of being fermented into sauerkraut and kimchee. The microbes that carry out fermentation need these vitamins, but also have the metabolic pathways to make their own from the starches and sugars present in the food, whereas we do not. We merely benefit from them pre-processing the food.
Now that we understand what's going on when we ferment, let's see this optimized method for making kimchee. Get some friends together and have a kimchee making party, and perhaps get some Korean food and a bottle of soju afterwards.
 This is a paraphrase of an observation on the discovery of penicillin from Cracked.com.