When making pickles at home, the salt ratio in the brine is usually kept at 3 to 5 percent of the water's weight; this level stops unwanted bacteria from growing while still letting the beneficial lactic acid bacteria that make pickles sour do their work. If the ratio is too low, the pickles risk spoiling; if it is too high, fermentation stalls and the pickles never turn sour.
How is the salt ratio calculated?
As a practical rule, adding 30 to 50 grams of rock or pickling salt per litre of water lands in the 3 to 5 percent range; that is roughly 2 to 3 tablespoons of salt per litre of water. Salt should not be poured over the vegetables before it fully dissolves; the brine should be stirred first and left until the salt is completely dissolved, since undissolved crystals can leave some vegetables over-salted and others under-salted. Rock salt or dedicated pickling salt is recommended over iodised table salt, since iodine and anti-caking additives can cloud the brine and interfere with fermentation.
How does the ratio change by vegetable?
For vegetables with high water content that should stay crunchy, such as cucumbers, the salt ratio is kept closer to 5 percent; this preserves crunch and balances out the vegetable's own liquid diluting the brine. For vegetables that naturally release their own liquid, such as cabbage, the ratio can be kept a bit lower, around 2 to 3 percent, since the vegetable's own juice mixes into the brine and raises the ratio anyway. For thin-skinned vegetables like peppers and tomatoes, keeping the salt ratio too high can give an unwanted result in both texture and taste.
What happens with too little or too much salt?
If the salt ratio is too low, unwanted bacteria in the brine can outgrow the lactic acid bacteria; this shows up as sliminess, off odours or mould in the pickles. If the salt ratio is too high, the beneficial bacteria slow down or stop working entirely; the pickles will not spoil in this case, but they never develop the expected sour taste and remain just a salty vegetable. In both cases, the way to fix the result is to prepare the brine with the right ratio from the start; adjusting the ratio after fermentation has begun rarely helps.
What matters during the brining period?
Vegetables need to stay fully submerged in the brine; pieces that float to the surface come into contact with air and raise the risk of mould, so a weight or a clean plate should hold them under the liquid. Keeping the jar at room temperature, out of direct sunlight, during fermentation helps the lactic acid bacteria work steadily; a very warm spot speeds up fermentation but can lead to an uneven, uncontrolled flavour. The jar lid should not be sealed tightly, and should be left loose enough to let gas escape; a tightly sealed jar can let carbon dioxide build up pressure that strains the lid or even cracks the jar.