Salt makes fermentation work
Lacto-fermentation relies on lactic acid bacteria naturally present on vegetables. They turn sugars into lactic acid, which sours and preserves the food. Salt is what gives them the advantage: it draws water and sugars out of the vegetables, slows down spoilage organisms and keeps vegetables crisp. Too little salt, and soft or moldy vegetables become more likely; too much, and fermentation slows down or stops.
Three methods
1. Dry salting. Shredded or finely cut vegetables, such as cabbage for sauerkraut or kimchi, are mixed with salt and pressed until they release enough juice to cover themselves. The salt is a percentage of the vegetable weight:
Salt = vegetable weight × percentage
2. Brine. Whole or chunked vegetables, such as cucumbers, carrots or green beans, are covered with salt water. The salt is a percentage of the water:
Salt = water weight × percentage
3. Equilibrium brine. The salt is calculated on the total weight of vegetables and water, so that both end up at the same concentration:
Salt = (vegetables + water) × percentage
Typical percentages
| Ferment | Salt |
|---|---|
| sauerkraut | 1.5 to 2.5% of the cabbage |
| kimchi (dry-salted) | 2 to 3% |
| carrots, beans, cauliflower in brine | 2 to 3.5% |
| cucumbers in brine | 3.5 to 5% |
| hot sauce mash | 2 to 5% |
Example
For 2 pounds (907 g) of shredded cabbage at 2%, you need about 18 g of salt, roughly 3 teaspoons of fine salt.
Tips for success
- Weigh the salt: a tablespoon of fine salt weighs about twice as much as a tablespoon of flaky kosher salt.
- Use salt without iodine or anti-caking agents.
- Keep vegetables under the liquid with a weight to prevent mold.
- Ferment at about 64 to 72 °F (18 to 22 °C) for steady fermentation.
- Use clean jars and leave headspace for gas, or use an airlock lid.
Food safety
Properly salted and submerged vegetable ferments are among the safest preserved foods, because the acidity quickly rises. Discard any batch with fuzzy mold throughout, a slimy texture or a putrid smell. A white film of kahm yeast on the surface is harmless but can be skimmed off.