|My cabbage fermentation container. One head of shredded cabbage mixed with sea salt. This can be done in a much larger container like a crock with many heads of cabbage. Salt pulls the water out of the cabbage and a weight is placed on-top of the cabbage to keep it submerged. After a little over a week, or after it stops bubbling, the sauerkraut is ready to eat.|
The process is very easy and only requires sea salt and cabbage. You must use sea salt or canning salt, otherwise your cabbage will not ferment. Simply shred your cabbage and them mix with the sea salt in a glass or stoneware container. Avoid plastic or metal containers as they can degrade in the fermentation process. Cabbage and other vegetables are traditionally done in a stoneware crock. I typically use gallon pickle jars or two liter beakers. The key is finding a container that you can place a weight in to keep the cabbage submerged under the liquid. Typically strait edged jars or crocks work best, jars with tops that curve inwards make the cabbage difficult to weigh down. When I mix the cabbage with the salt I usually add a handful of cabbage and then sprinkle it with salt (not too much!), then mix by hand (clean hands!) and repeat until I have filled my container or have no more cabbage left. The amount of salt to add is not an exact science, you can add to taste and usually less is better. You will need just enough salt though to remove enough liquid from the cabbage so it can be submerged. Also, make sure to mix very well so the salt is evenly distributed in the cabbage. Once you have finished mixing you must weigh down you cabbage, which will also help in extracting moisture, and then let it sit. Your weights can be any clean thing that you can find. People use rocks, glassware such as cups filled with water, wood, and even plastic bags filled with water. Check on the ferment everyday or so and press down on the weight, this ensures the cabbage remains submerged and releases carbon dioxide that forms as a result of fermentation. After a week or slightly more, or after the bubbles stop, your sauerkraut is ready to eat.
The process of making sauerkraut is known as lactic acid fermentation. Similar to alcohol fermentation with an input of sugar but different in that the output is lactic acid as opposed to ethyl alcohol. Several species of bacteria are responsible for sauerkraut fermentation. These bacteria are controlled by sugars in the cabbage, salt content, anaerobic conditions (without oxygen) by submerging the cabbage, and pH (acidity). During the first several days of fermentation coliform species of bacteria quickly consume all of the oxygen in the liquid and ferment, producing lots of carbon dioxide bubbles and dropping the pH from about 6 to around 4.5. The salty, anaerobic, and acidic conditions (pH~4.5) kill off coliforms around day four and are Leuconostic sp. bacteria quickly populate the cabbage. Leuconostic bacteria then produce lactic acid, dropping the pH to about 4.2 which kills them off and allows Lactobacillus sp. bacteria to replace them. Lactobacillus sp. continues production of lactic acid, dropping the pH to about 3.9 or so where it will stay for up to several months. It takes slightly more than a week for this process to happen depending on temperature and salt content. The sauerkraut is safe to eat at this point and full of healthy probiotic organisms (Lactobacillus sp.). In a week or two I will report back on the results of this sauerkraut experiment.