Fermentation basics

Anaerobic environment, beneficial bacteria

Lacto-fermentation requires an anaerobic (oxygen-free) environment. Beneficial Lactobacillus bacteria thrive without oxygen and produce lactic acid that preserves the food and creates the characteristic tangy flavor.

Food exposed above the brine is in contact with oxygen, where mold and harmful bacteria can grow. Keeping vegetables submerged below the brine is the single most important step in safe fermentation.

How much and why

Salt serves two functions: it draws water out of vegetables to create the brine, and it inhibits harmful bacteria while Lactobacillus establishes itself. The standard ratio for sauerkraut is 2 to 3 tablespoons of non-iodized salt per 5 pounds of cabbage.

Use non-iodized salt (canning salt, kosher salt, sea salt). Iodine can inhibit the beneficial bacteria and discolor the product.

When to worry and when not to

White film on the brine surface (kahm yeast) is harmless. Skim it off. Pink, black, or fuzzy mold on food above the brine means that food was not submerged. Remove the moldy portion; the submerged food below is usually still safe. Foul smell (not just tangy or sour) means something went wrong. Discard.