The Fermentation Process

• Cabbage transforms into sauerkraut when a selection of favorable microorganisms, including Lactobacillus bacteria, metabolize the cabbage’s natural sugars and produce lactic acid. These microorganisms simultaneously suppress other microbes that cause spoilage. Under the right conditions, the result is a tart, fermented pickle that lasts for several months in the refrigerator. White surface mold is normal and safe to scrape off as it forms, but discoloration, mushy texture and putrid odors indicate the kraut is rotten.

Be Shrewd With Salt

• Salt is essential to making sauerkraut because it draws the liquid from the cabbage to produce brine, which guards against the microbes that cause spoilage. However, too much salt can hinder the Lactobacillus bacteria needed for the fermentation process. Use about 3 tablespoons of fine salt or 4 tablespoons of coarse salt for each 5 pounds of cabbage. The additives in iodized table salt also interfere with fermentation, so choose non-iodized kosher salt or sea salt.

Add Water Wisely

• Most of the liquid for the sauerkraut’s brine comes from the cabbage itself, but sometimes it is necessary to add brine to completely submerge the cabbage. If you need more brine, avoid using chlorinated tap water. Chlorine destroys microbes, including the bacteria necessary for fermentation. Boiling tap water evaporates the chlorine, or you can purchase distilled water. Mix in about 1 tablespoon of salt per cup of water before adding it to the kraut.

Submerge and Store

• The cabbage must stay submerged to protect it from putrefying microbes. Pack the cabbage tightly, and weight it with a plate or other non-metal item to prevent pieces from floating to the surface. Cover the unsealed container with cloth to keep bugs out without trapping gases inside. Store the kraut at room temperature until it reaches the desired level of acidity, then seal it and transfer it to the refrigerator to slow microbe activity and extend its life.