Salt in Fermentation

All the micro-organisms needed for the start of wild fermentation are present on the vegetables, even after washing. The only thing that is needed is the addition of salt. Wild fermentation, also known as lactose-fermentation is an ancient form of food preservation using salt in contact with the vegetables to preserve the food. When the right salt to vegetable ratio is achieved, the environment will be ideal for the growth of the lactic acid-producing organisms to preserve the vegetables and keep the unwanted organisms at bay, whilst producing a delicious tangy sour taste.

Too much salt will slow down or stop the fermentation, therefore little production of lactic acid and no preservation, resulting in a very salty and unpleasant flavoured mix.

Too little salt will allow moulds and unwanted bacteria to grow and the vegetables will not stay crisp.

Which Salt To Use?

Ideally the best salt to use is one with no additives, and the only ingredient should be salt.

Although any salt will work in fermentation, some salts are better, making a better tasting and textured ferment. Table or iodised salt has additives such as anti-caking agents and preservatives which will inhibit the growth of the beneficial microbes, affecting the quality of the final product.

Sodium Bicarbonate in the salt:

Some table salts contain Sodium Bicarbonate (baking Soda), as an additive, this is an alkaline compound which can have unwanted effects on the fermentation process.
Texture Changes:
The alkaline nature of baking soda can affect the texture of the vegetables. It may cause them to become softer more quickly, which can be desirable for some vegetables but not for others that are prized for their crunch.
Impact on Beneficial Bacteria:
The changed pH environment might affect the growth rates and populations of various beneficial bacteria involved in fermentation. Some strains may thrive better, while others might be inhibited.
Risk of Off-Flavors:
If too much sodium bicarbonate is used, it can lead to off-flavours or a soapy taste in the final product.
It's important to note that traditional fermentation recipes typically don't include sodium bicarbonate. The natural process of fermentation usually produces the desired acidity and flavour profile without additional pH adjustment.

The salt of choice one that has salt as the only ingredient listed on the label.

Ways of adding salt.

The Self or dry brining method is used when making sauerkraut, relies on the moisture to be drawn out of the vegetable, by the direct contact with salt, to create a brine without the addition of water. The vegetables are finely cut and sprinkled with the salt, then packed tightly in the jar to remove any air pockets. 2% salt by weight is commonly used.

The Pre-brining method is used when making traditional kimchi involves the vegetables being soaked in a strong brine, 4-5% salt by weight. After soaking in the brine for several hours, the brine is drained off and the vegetables squeezed to remove more liquid. It is covered to keep out the air then left for the fermentation to complete.

The Brining method is used when the vegetables don't get compressed, such as pieces of carrots, green beans, cucumbers and asparagus. The vegetables and water are weighed to calculate the correct salt concentration. All the salt needed is added to the water (the brine) before pouring into the jar. 2% to 3% concentration is usually used for this technique.

How important is water?

The water used should be free of additives such as chlorine or fluoride, as found in tap water, these inhibit the fermentation. If you only have tap water on hand it can be boiled for 20 minutes then left to cool, or left in a wide bowl overnight to reduce the chlorine concentration. Filtered water, rain water and still mineral water are all good to use.

How much salt to use?

Fermentation of vegetables is quite forgiving, the ratios can be tweaked a little to appeal to your palate, once you have had some experience and become a confident fermenter. All salts weigh differently so spoon measurements aren't very accurate, it is best to measure the quantity needed by weight. Salting is a balancing act between helping the microbes to thrive and inhibiting the unwanted microbes, fortunately that's not hard to do.

To dry brine,
as is done when making sauerkraut, the amount of salt used is calculated as a percentage of the total weight of the vegetable to be packed into the jar. To make 1kg of cabbage with a 2% salt concentration, 20g of salt is added.

Calculating how much salt to use

To calculate, the amount vegetables in grams (e.g 1000g) is divided by 100, the answer is then multiplied by the percentage of salt required (e.g. 2%) this will give you the number of grams of salt to be added.

For Example:

1000 (number of grams of cabbage) ÷ 100 = 10.
Then 10 x 2 (because it's 2% we are after) = 20g of salt needed.

Another example using a different weight of cabbage, 800g and 3% salt needed:
800g ÷ 100 = 8
then 8 x 3% = 24g of salt needed.

Make a Brine for the Brine method

Make a brine for topping up the jar if the vegetables are looking dry, it's exactly the same only using the weight of the water instead of the vegetables, the maths is the same.

Firm vegetables like carrots, beets, cauliflower or cabbage are usually fermented in a 2% to 3% salt concentration. Wet vegetables such as cucumbers contain a lot of water, the salt draws out the moisture, this will dilute the brine so a little more salt is needed. A 3% to 5% brine is good for such wet vegetables. If your ferments are prone to getting mouldy or the weather is very hot you can increase the concentration of salt, but keep it under 5%.

The vegetables can be given a rinse in clean water just before consuming or cooking with if you find them too salty.