Fermented cabbage is a food that has been eaten for thousands of years. The process of fermenting cabbage allows it to be safely eaten long after the time that fresh cabbage would have spoiled. It is made by encouraging the growth of certain kinds of bacteria, known as lactic acid bacteria, which are used to preserve many different types of food as they eat lactose and excrete lactic acid. All that is needed to make fermented cabbage is salt or water, a container, and the cabbage itself.
Making fermented cabbage is a simple process, and there are many different variations. The cabbage simply needs to be submerged in a liquid and then left in a cool place for anywhere from a week to a number of months as the bacteria ferment it. There is no need to add lactic acid bacteria to cabbage because this type of bacteria can be found naturally in the vegetable.
The fermentation process requires a number of different conditions in order to transform raw cabbage into an edible fermented food. First, the cabbage must remain submerged in liquid so that it is not exposed to oxygen. The presence of oxygen during the fermentation process will cause the cabbage that is exposed to the air to mold, and while some types of mold are edible, there are some that can cause the fermented cabbage to go bad. Water, broth, or another liquid may be used to cover whole or roughly chopped cabbage, or the cabbage may be finely chopped and heavily salted so that the water can be drawn out of the cabbage itself.
Once the cabbage and liquid or the cabbage and salt are combined, the mixture needs to be kept away from oxygen and heat while it ferments. This can be accomplished by placing the mixture in an airtight container or by ensuring that the cabbage is kept below the surface of the liquid by weighing it down. Historically, containers used to make fermented cabbage were buried underground in order to keep them at a constant, cool temperature. In modern times refrigeration is often used to ferment the cabbage at a cool, but not cold, temperature.
A common dish in both Europe and Asia, fermented cabbage is one of the oldest dishes. Some of the more common types of this dish include the German dish sauerkraut and the Korean dish kimchi. There are many variations, and a variety of vegetables, herbs, and spices may also be added to the cabbage as it is fermenting.