Salt is an essential element of our life and our lifestyle too.
From our plates for the flavor to the winter roads for safety, salt has over 14,000 uses. Salt has been the reason for the rise of several civilizations. It has also caused rebellions and revolutions and started several wars. Without salt, the world as we know it would not exist. Salt, also known as table salt, or rock salt, is a mineral that is composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. It is essential for animal life in small quantities but is harmful to animals and plants in excess. Salt is one of the oldest, most ubiquitous food seasonings and salting is an important method of food preservation. The taste of salt (saltiness) is one of the basic human tastes.
Salt for human consumption is produced in different forms: unrefined salt (such as sea salt), refined salt (table salt), and iodized salt. It is a crystalline solid, white, pale pink, or light gray in color, normally obtained from seawater or rock deposits. Edible rock salts may be slightly grayish in color because of mineral content.
Chloride and sodium ions, the two major components of salt, are needed by all known living creatures in small quantities. Salt is involved in regulating the water content (fluid balance) of the body. The sodium ion itself is used for electrical signaling in the nervous system. Because of its importance to survival, salt has often been considered a valuable commodity during human history. However, as salt consumption has increased during modern times, scientists have become aware of the health risks associated with too much salt intake, including high blood pressure. Therefore health authorities have recommended limitations of dietary sodium. The United States Department of Health and Human Services recommends that individuals consume no more than 1500–2300 mg of sodium (3750–5750 mg of salt) per day depending on age.
Different natural salts have different minerality, giving each one a unique flavor. Fleur de sel, natural sea salt from the surface of evaporating brine in salt pans, has a unique flavor varying from region to region. In traditional Korean cuisine, the so-called "bamboo salt" is prepared by roasting salt in a bamboo container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud and has been shown to increase the anticlastogenic and antimutagenic properties of doenjang.
Completely raw sea salt is bitter because of magnesium and calcium compounds and thus is rarely eaten. The refined salt industry cites scientific studies saying that raw sea and rock salts do not contain enough iodine salts to prevent iodine deficiency diseases.
Unrefined sea salts are also commonly used as ingredients in bathing additives and cosmetic products. One example is bath salts, which use sea salt as its main ingredient and combined with other ingredients used for its healing and therapeutic effects.
Refined salt, which is most widely used presently, is mainly sodium chloride. Food grade salt accounts for only a small part of salt production in industrialized countries (3% in Europe) although worldwide, food uses account for 17.5% of salt production. The majority is sold for industrial use. Salt has great commercial value because it is a necessary ingredient in many manufacturing processes. A few common examples include the production of pulp and paper, setting dyes in textiles and fabrics, and the making of soaps and detergents.
The manufacture and use of salt are one of the oldest chemical industries. Salt can be 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. Rock salt deposits are formed by the evaporation of ancient salt lakes and maybe mined conventionally or through the injection of water. Injected water dissolves the salt, and the brine solution can be pumped to the surface where the salt is collected.
After the raw salt is obtained, it is refined to purify it and improve its storage and handling characteristics. Purification usually involves recrystallization. In recrystallization, a brine solution is treated with chemicals that precipitate most impurities (largely magnesium and calcium salts). Multiple stages of evaporation are then used to collect pure sodium chloride crystals, which are kiln-dried.
In Western cuisines, salt is used in cooking, and also made available to diners in salt shakers on the table. Table salt is refined salt, which contains about 97% to 99% sodium chloride. It usually contains substances that make it free-flowing (anticaking agents) such as sodium silicoaluminate or magnesium carbonate. Some people also add a desiccant, such as a few grains of uncooked rice, or a saltine cracker in salt shakers to absorb extra moisture and help break up clumps when anticaking agents are not enough. Table salt has a particle density of 2.165 g/cm3, and a bulk density (dry, ASTM D 632 gradation) of about 1.154 g/cm3.
In many East Asian cultures, salt is not traditionally used as a condiment. In its place, condiments such as soy sauce, fish sauce, and oyster sauce tend to have a high sodium content and fill a similar role to table salt in western cultures. They are most often used for cooking rather than as table condiments.