Lacto-fermentation takes advantage of the beneficial bacteria (including Lactobacillus) that are naturally present on the surface of fruits and vegetables including the cabbage called for in this recipe. When held at room temperature and submerged in brine, these healthy bacteria convert the natural sugars in the cabbage into lactic acid. The lactic acid will naturally preserve the kraut and inhibit the growth of harmful bacteria.
Much like canning, fermentation requires clean tools and surfaces to safeguard against potentially unsafe bacteria. Simply washing all the tools and equipment and your hands with soap and hot water before beginning the recipe is sufficient. This will ensure that you have begun the process with the clean environment necessary for successful and safe fermentation.
Rinse the head of cabbage in cold water. Quarter the cabbage, removing the core before finely shredding each quarter. Place shredded cabbage in a large bowl. Add the sea salt, tossing to evenly distribute. Allow the cabbage and salt to rest for 10 minutes.
Massage the sea salt vigorously into the cabbage for about 5 to 10 minutes. Working the sea salt with the shredded cabbage will help to draw liquid out of the cabbage and begin the process of breaking down the fibrous nature of the cabbage.
If you have time, allow the massaged cabbage to rest in the bowl as the salt will draw out the liquid. If you do not have time to wait, simply pack the cabbage into a quart-size, wide-mouth Mason jar. Use a pounder or wooden spoon to really press down and pack the cabbage in. The top of the cabbage should be even to the shoulder of the jar. If there isn't enough liquid to cover the cabbage by one inch, add enough brine to cover.
Secure your Kraut Source unit or lid on the jar. Take care not to tighten the lid too tightly. As the cabbage ferments, carbon dioxide will be released. If the carbon dioxide is not allowed to safely escape the jar, it can cause the jar to break or the lid to be forced off of the jar.
The innovative Kraut Source unit contains a spring and a press to hold the cabbage underneath the surface of the liquid while allowing the carbon dioxide to escape. If you are using a standard lid, a piece of the cabbage’s core or a small weight can be used to keep the sliced cabbage below the liquid .
The lid can be removed every few days and replaced to adequately vent the excess carbon dioxide. During fermentation, the cabbage must be completely submerged in the liquid to prevent spoilage. Additional brine can be added as needed to completely cover the submerged cabbage.
Allow the kraut to ferment at room temperature for 5-7 days or several weeks to develop the desired flavor. After 5 days, begin tasting the kraut every few days to determine if the flavor is to your liking. When the taste is agreeable, transfer the kraut to the refrigerator. Any weight or cabbage core used to keep the kraut submerged can be removed at this point.