Salt
Edible salt is a crystalline solid, white, pale pink or light grey in colour. Edible salt can mean unrefined salt, refined salt, table salt or iodised salt. It can be obtained from seawater or from rock deposits. Sea salt comes in fine or larger crystals. In nature, it includes not only NaCl, but also other vital minerals, including trace minerals. Rock salt which is edible after being refined, is grayish because it is less pure and contains more minerals. Salt craving is always trace mineral lack. Whatever its exact composition, it is an irreplaceable substance, necessary for the survival of all living creatures, including humans. Water and salt regulate the water content of the body (fluid balance). Salt flavour is one of the four basic tastes.
History of edible salt
In the past, salt was difficult to obtain, but had a great importance in food preservation and as food additive, because it is vital for the regulation of water content. Therefore, it was highly valued. Roman soldiers were partially payed with salt, and this is still evident in the English language as the word salary derives from the Latin word salarium that means payment in salt (Latin sal). It was also of high value to Hebrews, Greeks and other peoples of Antiquity and Middle Ages and through the most part of the 19th century when it finally became easier to produce it and its price became more reasonable. The main reason for this was that it finally became possible to obtain it by mining instead from the evaporation of seawater, as this is the cheaper of the two processes.
Unrefined salt
Main article: Sea salt
Unrefined sea salt that is obtained from the seawater, has 84 chemical elements and is much healthier than refined salt.
Refined salt
Refined salt, that is nowadays most widely used, is mainly sodium chloride. Only about 7% of the refined salt is used as a food additive. The majority of it is sold for industrial use, from manufacturing pulp and paper to setting dyes in textiles and fabric, to producing soaps and detergents, and has great commercial value.
Production methods
The manufacture and use of salt is one of the oldest chemical industries. Salt is mined from deposits that were created after evaporation of salt lakes or is obtained as a brine by introducing water into the deposits to dissolve the salt and then pumping the solution to the surface. Salt is also obtained by evaporation of seawater, usually in shallow basins warmed by sunlight; salt so obtained was formerly called bay salt, and is now often called sea salt or solar salt. Most refined salt is obtained from deposits, however table salt is obtained from seawater.
After the raw salt is obtained, at first chemical impurities are removed. During the refining, natural sea salt or rock salt is stripped of almost all the elements it contains, depending on the purity that should be reached. Two anticaking agents ordinary used are sodium alumino-silicate and alumino-calcium silicate. Both substances contain aluminum, a toxic metal that is believed to be one of the factors contributing to Alzheimer's disease.
This is followed by drying of salt. Major producers dry their salt in huge kilns where it is heated to temperature of about 650° C (1200 F), which changes its chemical structure.
At the end, it is packed and distributed.
Table salt
Table salt is refined salt, that contains almost exclusively two or three chemical elements. The two most important of them are sodium (39%)and chloride (61%), combined together as NaCl. It also contains substances that make it free floating. It is mainly used in cooking and as a table condiment. However, the salt that is sold as a food additive, contains also other elements, notably aluminium, whose content is not allowed to exceed the maximum set by the national standards as well as international standards (WHO) for food quality.
Iodized salt
Iodized salt is table salt, that is enriched with iodine (sodium iodide). It is especially important as preventative for goiter (hypothyrodism) in areas where natural iodine is scarce.
Sour salt
See: citric acid