Salt part I: What is salt?

In the next few posts I would like to talk a little bit about salt as it takes a very important part in sauce making and cooking in general.

The Oxford dictionary defines salt as a white crystalline substance which gives seawater its characteristic taste and is used for seasoning or preserving food. It is also known by its little chemical name; sodium chloride or NaCl.
Salt is a simple inorganic mineral that is part of all the basic cooking preparation from dough to batters, cured food, pickles, cheese making, soy sauce or enliven foods. It is an essential nutrient that our body cannot do without. But it can, also, damage it if in excess. Nowadays, salt is used in large amounts in industrial manufactured food of all sorts as well as being used to de-icing roads.

Salt has been gathered in its crystalline form from the seacoast since prehistoric times. Salt can, also, come from rock salt deposit (like this one in Poland, see picture) that formed when ancient seas were isolated and evaporated when land masses rose millions of years ago. Hen throughout centuries some of them were covered by layers of sediments or later geological processes.

Salt extraction from rock salt deposit has been industrialised in the 18th century. Salt deposit are mined or extracted by a process called: “mining by solution”. Most rock salt is done that way. Water is pumped into the deposit. Then, when all the salt is dissolved the brine is pumped and evaporated down in a vacuum chamber to form the solid crystals.
Sea salt is produced by gradual evaporation from open air salt pans in region where the climate is favourable. But nowadays, most of the sea salt production is made though vacuum evaporation too.
Salt producers have to overcome the many bitter minerals contained in seawater: the chloride and sulphate salts of magnesium and calcium. Two techniques are used to remove these bitter salts. The first one consists in dissolving the salt crystals in some water, and then ad some sodium hydroxide and carbon dioxide, which precipitate these bitter salts, and then evaporate this brine, usually using the vacuum evaporation process.

Sea salt harvester can either use the first technique or the one that use the more traditional way of slow evaporation in open-air pans have to carefully remove the first layer of calcium chloride which has crystallised first. Then, harvest the sodium chloride crystals that are forming after further evaporation, leaving the magnesium salts being washed off by the new batch of sea water.

Salt, we eat too much of it, but cannot leave without it! Salt is a flavour enhancer and preservative agent: It strengthens the impression of aromas and suppresses the sensation of bitterness. Because a concentrated solution draws water out of living cell by osmosis; water in the less concentrated fluid moves out of the cell to relieve the imbalance, in consequence if there is a sufficient concentration of salt in the food it can prevent the growth of spoilage bacteria. This reduction of the water in the environment stops or reduces the growth of dangerous (except for the listeria that does not need a lot of water to survive) bacterium while allowing harmless, flavour producing and more salt tolerant ones to grow, like in cheese making for example. Salt is also, an essential nutrient that our body requires to function properly: It helps balancing the osmotic pressure within our cells as well as balancing the levels of potassium and other ions in the fluid portion of our blood.

But, as there is always a but with all good things, salt can become a serious hazard for our body. In our modern dietary habits of an increasing consumption of manufactured food where salt is not always clearly visible, it has become very easy to exceed our recommended intake of one gram per day (more if sweating a lot). For example, in the U.S the average daily intake of salt per capita was 10 grams, 10 times the recommendations (figure for the year 2000). This type of behaviour leads to an excess of plasma in our blood vessels causing high blood pressure. Medical scientists have linked it to a higher risk of stroke and various other heart conditions. None the less, studies have shown that a low-salt diet have only a small impact on high blood pressure and this only on some people.
Furthermore, low-salt diets have side effects of their own, such as a noticeable increase in blood cholesterol levels. This is not all, a diet high in salt, on the top of raising the blood pressure increase the pressure on our kidneys. To get rid off the excess sodium in our blood, our kidneys have to work harder to filter it out. It can worsen chronic kidney diseases. This is why it is advisable to have serious control of its salt intake for people with such conditions. There is also evidence, that a diet high in sodium chloride can cause calcium losses. This factor is very important for people suffering from osteoporosis.
Finally, our body does not only have one way to excrete excess salt, we have seen that our kidney filter it out, it is also done through sweating, it also, done through our digestive system. Salty food exposes our intestines to potential cell damaging salt concentrations. Recent studies conducted in Asia show evidence that rich salt diets are linked to several cancer of the digestive system.
So, in view of all those scary conditions linked to a salt rich diet, it is important to understand that they are no drug free solutions to treat them and that moderation is the key. New regulations are coming to push the food industry to be more clear and truthful about the salt content of their products using clearer labelling and reducing the added salt in their food. A balance diet rich in vegetables, fruits and seeds will also, help to solve such health problems. And I would ad to these few recommendations: COOK your own food, you are sure to know what is in it!

As sodium chloride is essential to its basic functions, the body has a sensory system to let him know where to find salt. It’s on either sides of the front of our tongue that small saltiness receptors are found. The basic liking for salt is innate to us, but not everyone can sense salt in the same way.
Studies have found that most young adults can identify as salty a water solution with a concentration of sodium chloride of 0.05%. It is the equivalent of a teaspoon of salt diluted in 10 litres of water. As we age our sensitivity to salt decrease. In comparison, a person aged 60 years of age needs up to twice the concentration of salt to detect saltiness, than a young adult one. This amount of sodium chloride represents the equivalent of the natural concentration of this ion in our plasma. Note that most food manufacturer use a concentration of 1 to 3% of salt in their products, which is 10 a 30 folds the natural concentration of our plasma. These concentrations can lead to an increase in the risk of developing high blood pressure. It also, gets our body used to these levels of saltiness. The body becomes dependent to a high concentration of salt in food. Sensitivity to salt can be, easily, weaned out by a gradual decrease of the salinity of the food someone have. It takes up to 2 to 4 months to train the body to a normal saltiness expectation.
To be continued....
Few links to web-sites about salt for further information: The story of salt and its political role in Brittany, Traditional salt gathering, Salt and health.