The higher the NaCl concentration and the faster the evaporation process is, the smaller and the more regular the crystal of salt will be. It will also have a more cubical shape. If the concentration of sodium chloride is mild, like in the sea water, and if this natural brine follows a slow drying process, like the one in the pans of the Guérandes region in France, the salt crystals that will form will be larger and flakier.
The physical properties of salt are as follow:
- At room temperature water can dissolve 95% of its weight in salt to give a concentration of 26% that gives a saturated solution that boils at 108C/ 228F at sea level.
- Solid salt crystals melt at 800C/ 1600F and evaporate at 1500C/ 3000F.
The size of the particles of salt determines the speed at which they will dissolve. This is very important when cooking. For example, it is preferable to use table salt for baking as a dough is a low moisture mixture. A bread dough made by autolysis*, may dissolve flaky salt 4-5 times faster than granules, but fine salt (like table salt) will do so 20 times faster.
Types of salts
Granulated table salt: It comes in small cubic shaped crystals of sodium chloride. It is the densest of all the types of salts and the slowest to dissolve too. It is often supplemented with additives (up to 2% of its total weight). The first ones are used to prevent the salt crystals surface to absorb water. The most commonly additives used in that purpose are: aluminium and silicon compounds of sodium and calcium, silicon dioxide and magnesium carbonate. The second types of additives used in table salt are called humectants. Their job is to prevent the crystals from excessive drying and caking. Note that these anti-caking agents do not dissolve as easily as salt. This has for effect to cloud brine for pickled vegetables. It is advisable to use a type of salt that is additive free.
Iodized salt: This is a type of granulated salt that has been supplemented or naturally contains traces of potassium iodide. This mineral is essential for the proper functioning of the thyroid gland. The thyroid regulates the body heat production, the protein metabolism and development of the nervous system. Iodized salt is sensitive to acidity so manufacturers supplement this type of salt with stabilizing agents such as traces of sodium carbonate or thiosulfate and sugar.
Flake salt: This type of salt comes into the shape of flat, large particles. Flake salt is produced by either the natural evaporation of the mother brine or by mechanically rolling granulated salts. One of the best known one is the Maldon sea salt from the south coast of England.
Kosher salt: This type of salt comes in coarse particles, often flakes and is not iodized as it is meant to remove impurities. Kosher salt is used as part of the koshering process to draw blood out of meats according to the Jewish dietary laws.
Unrefined sea salt: This type of salt is harvested in the same way that plant crops. The beds are managed and tended accordingly with nature rhythm. The tending consists of a slow evaporation of the sea water. It can take up to five years. Once harvested the salt crystals are generally washed to get rid of their surface impurities then dried. In the case of unrefined salt, the salt crystals conserve their surface coating of algae, minor minerals and a bunch of salt-tolerant bacteria. Unrefined salt therefore carries traces of magnesium chloride and sulphate and calcium sulphate which give it a slight bitterness. It also, carries particles of clay and other sediments which give it its recognisable grey colour (in France unrefined salt is called sel gris, grey salt).
Fleur de sel: Meaning “flower of salt”, is the finest and most delicate sea salt product. Coming from the west and central-west coastal region of France (such as the Guérande region and the island of Oléron), this type of salt consist of the crystals that form and accumulate at the surface of the salt pans when the humidity and sea breezes are right. The salt crystals are gently raked off the surface before they fall below the surface where the ordinary grey sea salt accumulates. Fleur the salt crystals are white, moist, delicates flakes that do not carry any sediment particles. It is said that fleur de sel takes its particular flavour from the algae and other materials that coat the crystals, but no real studies have been made into where sea salt aroma comes from. Due to the labour involved to its gathering, fleur de sel is a quite expensive product and is usually used as a last minute condiment.
Fig 1 Fig 2 Flavoured and coloured salts: These salt specialities are usually made using fine salt. Some of the most known ones are: celery salt made with fine salt and ground celery seeds or pulverized dried celeriac; garlic salt made of dried garlic and fine salt; hickory salt made of sea salt and pulverised smoked hickory chips or the roast smoked salts from Wales (Fig 2), Denmark and Korea.
Coloured salts include the “Indian black salt” (Fig 1), which is more of a pink-grey when ground. It is an unrefined mixture of minerals with a sulphurous smell. Black and red Hawaiian salts consist of a mixture of sea salt with finely ground lava, clay or coral.
Tenderizing salt: Used to tenderize meats (in home cooking only. Its use is banned for meat processors and meat products manufacturers, and restaurants), this type of salt is made of ordinary table salt with 2 to 3% of papain.
Pickling salt: It is a preservative agent also known by its E-number: E250. It is made of sodium chloride in which is added sodium or potassium nitrates and sodium nitrite (10% max). It is manly used in the making of delicatessens and pates.
Saltpetre: It is not made of sodium chloride but potassium nitrate. I included to this list because of its name. From the Latin: sal petrae which means salt coming from rocks, saltpetre is formed of small, white crystals of potassium nitrates. In the past it was gathered by grating the walls of cellars. Nowadays It is manufactured. Due to its strong bactericide powers it is used since a very long time in the making of delicatessens and smoked and cured meats. It is always used with half its weight of sugar because of its very bitter taste and its use is severely regulated.
Oh these two posts on salt are very interesting. I am sure I will return for reference. Thank you Yann.
Hi Lori lynn,
nice to read from you. Thanks for your comment. There is a third part to the salt topic as well as a couple recipes on the way to complement these articles.