What is salt?

 

Salt is a white, crystalline mineral, the main ingredient of which is sodium chloride (NaCl).

 

Salt is a chemical compound with a specific structure and certain characteristics. Salt consists of ions, positively charged cations and negatively charged anions (metal ion [cation] + acid residue [anion]). In general, a substance consisting of sodium cation and chloride anion is considered to be salt. Sodium chloride is one of the most important salts of hydrochloric acid. Colourless, crystalline substance, soluble in water (26% solution at 25°C). Naturally occurring as rock salt, in the form of mineral halite, in the form of mineral sylvinite (KCl • NaCl), in salt lakes, in the sea (1.5%) and ocean (2.72%) water, also in ground water. Salt is obtained from natural deposits (rock salt) or by evaporating salt water. Salt is an important raw material for the chemical industry, for the production of soda, chlorine, etc.

 

In everyday life, salt is used to improve the taste of food, as a preservative substance for salting (meat, mushrooms, fish, vegetables, and skins). Humans and animals need salt for normal development of many vital processes. The percentage of sodium and chloride in NaCl are divided unequally, as one gram of NaCl consists of 0,4 g sodium and 0,6 g chloride. This is related to the different atomic mass of these two elements, as one mol of sodium corresponds to 23 g and one mol of chloride corresponds to 35.5 g.

 

Salt is classified according to the type of extraction

 

In terms of global demand for salt, 30% is obtained from sea water and from salt-containing inland waters, while the rest of the salt comes from rock salt deposits.

 

Rock salt or coarse salt

 

Rock salt deposits were formed from sea water, in an evaporation process, millions of years ago. Rock salt is broken down, crushed, purified and prepackaged using mining methods. Rock salt is almost pure NaCl, and this kind of salt is commonly used in the industry, including food industry, or sold as common or table salt. When selling salt, its degree of grinding or granulation is specified (0-3).

 

Vacuum salt or evaporated salt

 

Can be obtained in two ways. The solid rock salt dissolves in ground waters and thus salt water springs are formed, which come to the surface or are found as underground salt water, underground salt lakes. In addition to the natural salt water or solution, there are also industrial solutions of salt water obtained by supplying water to salt deposits with a “pipe-in-pipe” system. Evaporated salt is obtained in industrially developed salt plants by means of closed evaporative / vacuum evaporator. In these facilities, water evaporates under energy-saving low-atmospheric pressure. Evaporated salt of different degrees of granulation can also be obtained.

 

Sea salt

 

Salt is obtained from sea water, ocean water, and inland waters containing salt by evaporation. In salt ponds, the water evaporates from solar heat from spring to fall. Only 80% of the sea salt is constituted by NaCl, the rest is constituted by other compounds. These compounds are separated when the water has not completely evaporated. Specific compounds, such as gypsum (calcium sulphate) as well as magnesium and calcium salts, are separated in certain stages. Sea salt is also obtained industrially.

 

The sea salt sold on the market contains 98% NaCl. It should be noted that the iodine content in sea salt is insignificant, slightly more than in rock salt. Therefore, sea salt is not an alternative to iodised salt.

 

The addition of certain chemicals (calcium carbonate, calcium silicate, silicic acid, magnesium carbonate, calcium or sodium hexacyanoferrate) is permitted under the law in order for the salt to have a physical property such as solubility and not to form lumps.

 

Salt is classified according to the type of use:

 

• Table or common salt
• Salt for food production
• Technical or industrial salt

 

Salt is classified according to the type of granulation:

 

• Fine salt
• Coarse salt

 

Salt is classified according to the type of added substances:

 

• Iodised salt – a iodine compound is added
• Fluoridated salt – a fluorine compound is added
• Salt with vitamins – a vitamin complex is added
• Seasoned salt – various spices are added
• Salt with reduced Na content – reduced NaCl content and added magnesium, also KCl
• Mineral salt – various minerals are added

 

Specific types of salt:

 

• Flake salt (white, salt grains resemble matte-glass pyramids)
• Himalayan salt (pink salt crystals of various degrees of granulation)
• Hawaiian salt (black and rust-coloured salt crystals of various degrees of granulation)
• Black salt (various degrees of granulation, from dark grey to black)
• Kosher salt (white, fine crystals)
• Fleur de sel (white chips)

 

Sources: Inga Ansone, Master’s paper “Salt in the process of food production”. 1997, Jelgava, Latvia University of Agriculture.