Salt is a
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
composed primarily of
sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
(NaCl), a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
belonging to the larger class of
salts
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...
; salt in the form of a natural
crystalline
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
mineral is known as rock salt or
halite
Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, p ...
. Salt is present in vast quantities in
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
. The open ocean has about of solids per liter of sea water, a
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
of 3.5%.
Salt is essential for life in general, and
saltiness
The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...
is one of the
basic human tastes. Salt is one of the oldest and most ubiquitous food
seasoning
Seasoning is the process of supplementing food via herbs, spices, salts, and/or sugar, intended to enhance a particular flavour.
General meaning
Seasonings include herbs and spices, which are themselves frequently referred to as "seasonings". Ho ...
s, and is known to uniformly improve the taste perception of food, including otherwise unpalatable food.
Salting,
brining
In food processing, brining is treating food with brine or coarse salt which preserves and seasons the food while enhancing tenderness and flavor with additions such as herbs, spices, sugar, caramel or vinegar. Meat and fish are typically brined ...
, and
pickling
Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is called a ...
are also ancient and important methods of
food preservation
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit ...
.
Some of the earliest evidence of salt processing dates to around 6,000 BC, when people living in the area of present-day Romania boiled
spring water
A spring is a point of exit at which groundwater from an aquifer flows out on top of Earth's crust (pedosphere) and becomes surface water. It is a component of the hydrosphere. Springs have long been important for humans as a source of fresh w ...
to extract salts; a
salt-works in China dates to approximately the same period. Salt was also prized by the ancient
Hebrews
The terms ''Hebrews'' (Hebrew: / , Modern: ' / ', Tiberian: ' / '; ISO 259-3: ' / ') and ''Hebrew people'' are mostly considered synonymous with the Semitic-speaking Israelites, especially in the pre-monarchic period when they were still no ...
,
Greeks
The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group and nation indigenous to the Eastern Mediterranean and the Black Sea regions, namely Greece, Cyprus, Albania, Italy, Turkey, Egypt, and, to a lesser extent, oth ...
,
Romans
Roman or Romans most often refers to:
*Rome, the capital city of Italy
* Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a lette ...
,
Byzantines,
Hittites
The Hittites () were an Anatolian people who played an important role in establishing first a kingdom in Kussara (before 1750 BC), then the Kanesh or Nesha kingdom (c. 1750–1650 BC), and next an empire centered on Hattusa in north-centra ...
,
Egyptians
Egyptians ( arz, المَصرِيُون, translit=al-Maṣriyyūn, ; arz, المَصرِيِين, translit=al-Maṣriyyīn, ; cop, ⲣⲉⲙⲛ̀ⲭⲏⲙⲓ, remenkhēmi) are an ethnic group native to the Nile, Nile Valley in Egypt. Egyptian ...
, and
Indians. Salt became an important
article of trade and was transported by boat across the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
, along specially built
salt road
A salt road (also known as a salt route, salt way, saltway, or salt trading route) refers to any of the prehistoric and historical trade routes by which essential salt was transported to regions that lacked it.
From the Bronze Age (in the 2nd m ...
s, and across the
Sahara
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
on
camel caravan
A camel train or caravan is a series of camels carrying passengers and goods on a regular or semi-regular service between points. Despite rarely travelling faster than human walking speed, for centuries camels' ability to withstand harsh condi ...
s. The scarcity and universal need for salt have led nations to go to war over it and use it to raise
tax
A tax is a compulsory financial charge or some other type of levy imposed on a taxpayer (an individual or legal entity) by a governmental organization in order to fund government spending and various public expenditures (regional, local, or n ...
revenues. Salt is used in religious ceremonies and has other cultural and traditional significance.
Salt is processed from
salt mines
Salt mining extracts natural salt deposits from underground. The mined salt is usually in the form of halite (commonly known as rock salt), and extracted from evaporite formations.
History
Before the advent of the modern internal combustio ...
, and by the
evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
of seawater (
sea salt
Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking, cosmetics and for preserving food. It is also called bay salt, solar salt, or simply salt. Like mined rock salt, production of sea sa ...
) and mineral-rich spring water in shallow pools. Its major industrial products are
caustic soda
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alka ...
and
chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
; salt is used in many industrial processes including the manufacture of
polyvinyl chloride,
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s,
paper pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw mate ...
and many other products. Of the annual global production of around two hundred million
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s of salt, about 6% is used for human consumption. Other uses include water conditioning processes,
de-icing
Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or preve ...
highways, and agricultural use. Edible salt is sold in forms such as sea salt and table salt which usually contains an
anti-caking agent
An anticaking agent is an additive placed in powdered or granulated materials, such as table salt or confectioneries, to prevent the formation of lumps (caking) and for easing packaging, transport, flowability, and consumption. Caking mechanisms d ...
and may be
iodised to prevent
iodine deficiency
Iodine deficiency is a lack of the trace element iodine, an essential nutrient in the diet. It may result in metabolic problems such as goiter, sometimes as an endemic goiter as well as congenital iodine deficiency syndrome due to untreated cong ...
. As well as its use in cooking and at the table, salt is present in many processed foods.
Sodium is an
essential nutrient
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
for human health via its role as an
electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
and
osmotic solute.
[ Excessive salt consumption may increase the risk of ]cardiovascular diseases
Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
, such as hypertension
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
, in children and adults. Such health effects of salt
The health effects of salt are the conditions associated with the consumption of either too much or too little salt. Salt is a mineral composed primarily of sodium chloride (NaCl) and is used in food for both preservation and flavor. Sodium ions ...
have long been studied. Accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods. The World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
recommends that adults consume less than 2,000 mg of sodium, equivalent to 5 grams of salt per day.
History
All through history, the availability of salt has been pivotal to civilization. What is now thought to have been the first city in Europe is Solnitsata
Solnitsata ( bg, Солницата, "The Saltworks") was a prehistoric town located in present-day Bulgaria, near the modern city of Provadia. Believed by archaeologists to be the oldest town in Europe, Solnitsata was a fortified stone settlement ...
, in Bulgaria
Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...
, which was a salt mine, providing the area now known as the Balkans
The Balkans ( ), also known as the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the who ...
with salt since 5400 BC. Even the name Solnitsata means "salt works".
While people have used canning
Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...
and artificial refrigeration
The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
to preserve food for the last hundred years or so, salt has been the best-known food preservative, especially for meat, for many thousands of years. A very ancient salt-works operation has been discovered at the Poiana Slatinei archaeological site next to a salt spring in Lunca, Neamț County
Neamț County () is a county ( județ) of Romania, in the historic region of Moldavia, with the county seat at Piatra Neamț. The county takes its name from the Neamț River.
Demographics
Population
In 2011, it had a population of 470,76 ...
, Romania. Evidence indicates that Neolithic
The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts ...
people of the Precucuteni Culture were boiling the salt-laden spring water through the process of briquetage
Briquetage or very coarse pottery (VCP) is a coarse ceramic material used to make evaporation vessels and supporting pillars used in extracting salt from brine or seawater. Thick-walled saltpans were filled with saltwater and heated from below ...
to extract the salt as far back as 6050 BC. The salt extracted from this operation may have had a direct correlation to the rapid growth of this society's population soon after its initial production began. The harvest of salt from the surface of Xiechi Lake
Xiechi Lake (), also called Yuncheng yanchi (Yuncheng Salt Lake) is the largest natural lake in Shanxi in Northern China. It is a saline lake
used for production of salt.
In the summertime intense light and heat cause the algae ''Dunaliella sali ...
near Yuncheng
Yuncheng is the southernmost prefecture-level city in Shanxi province, People's Republic of China. It borders Linfen and Jincheng municipalities to the north and east, and Henan (Luoyang and Jiyuan to the east, Sanmenxia to the south) and Shaan ...
in Shanxi
Shanxi (; ; formerly romanised as Shansi) is a landlocked province of the People's Republic of China and is part of the North China region. The capital and largest city of the province is Taiyuan, while its next most populated prefecture-lev ...
, China, dates back to at least 6000 BC, making it one of the oldest verifiable saltworks.
There is more salt in animal tissues, such as meat, blood, and milk, than in plant tissues.[ ]Nomad
A nomad is a member of a community without fixed habitation who regularly moves to and from the same areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the popu ...
s who subsist on their flocks and herds do not eat salt with their food, but agriculturalists, feeding mainly on cereals and vegetable matter, need to supplement their diet with salt. With the spread of civilization, salt became one of the world's main trading commodities. It was of high value to the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites and other peoples of antiquity. In the Middle East, salt was used to ceremonially seal an agreement, and the ancient Hebrews made a " covenant of salt" with God and sprinkled salt on their offerings to show their trust in him. An ancient practice in time of war was salting the earth
Salting the earth, or sowing with salt, is the ritual of spreading salt on the site of cities razed by conquerers. It originated as a curse on re-inhabitation in the ancient Near East and became a well-established folkloric motif in the Middle ...
: scattering salt around in a defeated city to prevent plant growth. The Bible
The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts of a ...
tells the story of King Abimelech
Abimelech (also spelled Abimelek or Avimelech; ) was the generic name given to all Philistine kings in the Hebrew Bible from the time of Abraham through King David. In the Book of Judges, Abimelech, son of Gideon, of the Tribe of Manasseh, is ...
who was ordered by God to do this at Shechem
Shechem ( ), also spelled Sichem ( ; he, שְׁכֶם, ''Šəḵem''; ; grc, Συχέμ, Sykhém; Samaritan Hebrew: , ), was a Canaanite and Israelite city mentioned in the Amarna Letters, later appearing in the Hebrew Bible as the first cap ...
, and various texts claim that the Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
general Scipio Aemilianus Africanus
Publius Cornelius Scipio Africanus Aemilianus (185–129 BC), known as Scipio Aemilianus or Scipio Africanus the Younger, was a Roman general and statesman noted for his military exploits in the Third Punic War against Carthage and during the ...
ploughed over and sowed the city of Carthage
Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classi ...
with salt after it was defeated in the Third Punic War
The Third Punic War (149–146 BC) was the third and last of the Punic Wars fought between Carthage and Rome. The war was fought entirely within Carthaginian territory, in modern northern Tunisia. When the Second Punic War ended in 201 ...
(146 BC).
Salt may have been used for barter
In trade, barter (derived from ''baretor'') is a system of exchange in which participants in a transaction directly exchange goods or services for other goods or services without using a medium of exchange, such as money. Economists distingu ...
in connection with the obsidian
Obsidian () is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock.
Obsidian is produced from felsic lava, rich in the lighter elements s ...
trade in Anatolia
Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
in the Neolithic Era
The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts ...
. Salt was included among funeral offerings found in ancient Egyptian tombs from the third millennium BC, as were salted birds, and salt fish. From about 2800 BC, the Egyptians began exporting salt fish to the Phoenicia
Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their histor ...
ns in return for Lebanon cedar
''Cedrus libani'', the cedar of Lebanon or Lebanese cedar (), is a species of tree in the genus cedrus, a part of the pine family, native to the mountains of the Eastern Mediterranean basin. It is a large evergreen conifer that has great religi ...
, glass, and the dye Tyrian purple
Tyrian purple ( grc, πορφύρα ''porphúra''; la, purpura), also known as Phoenician red, Phoenician purple, royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye. The name Tyrian refers to Tyre, Lebanon. It is ...
; the Phoenicians traded Egyptian salted fish and salt from North Africa
North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...
throughout their Mediterranean trade empire. Herodotus
Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire (now Bodrum, Turkey) and a later citizen of Thurii in modern Calabria ( Italy). He is known f ...
described salt trading routes across Libya back in the 5th century BC. In the early years of the Roman Empire, roads were built for the transportation of salt from the salt imported at Ostia to the capital.
In Africa, salt was used as currency south of the Sahara, and slabs of rock salt were used as coins in Abyssinia
The Ethiopian Empire (), also formerly known by the exonym Abyssinia, or just simply known as Ethiopia (; Amharic and Tigrinya: ኢትዮጵያ , , Oromo: Itoophiyaa, Somali: Itoobiya, Afar: ''Itiyoophiyaa''), was an empire that historica ...
. The Tuareg
The Tuareg people (; also spelled Twareg or Touareg; endonym: ''Imuhaɣ/Imušaɣ/Imašeɣăn/Imajeɣăn'') are a large Berber ethnic group that principally inhabit the Sahara in a vast area stretching from far southwestern Libya to southern A ...
have traditionally maintained routes across the Sahara
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
especially for the transportation of salt by Azalai
The Azalai (Tamasheq, var. Azalay) is a semi-annual salt caravan route practiced by Tuareg traders in the Sahara desert between Timbuktu and the Taoudenni salt mine in Mali, or the act of traveling with a caravan along that route.
The other maj ...
(salt caravans). The caravans still cross the desert from southern Niger to Bilma
Bilma is an oasis town and commune in north east Niger with, as of the 2012 census, a total population of 4,016 people.
It lies protected from the desert dunes under the Kaouar Cliffs and is the largest town along the Kaouar escarpment. It ...
, although much of the trade now takes place by truck. Each camel takes two bales of fodder
Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food g ...
and two of trade goods northwards and returns laden with salt pillars and dates. In Gabon, before the arrival of Europeans, the coast people carried on a remunerative trade with those of the interior by the medium of sea salt. This was gradually displaced by the salt that Europeans brought in sacks, so that the coast natives lost their previous profits; as of the late 1950s, sea salt was still the currency best appreciated in the interior.
Salzburg
Salzburg (, ; literally "Salt-Castle"; bar, Soizbuag, label=Bavarian language, Austro-Bavarian) is the List of cities and towns in Austria, fourth-largest city in Austria. In 2020, it had a population of 156,872.
The town is on the site of the ...
, Hallstatt
Hallstatt ( , , ) is a small town in the district of Gmunden, in the Austrian state of Upper Austria. Situated between the southwestern shore of Hallstätter See and the steep slopes of the Dachstein massif, the town lies in the Salzkammergut ...
, and Hallein
Hallein () is a historic town in the Austrian state of Salzburg. It is the capital of Hallein district.
Geography
The town is located in the ''Tennengau'' region south of the City of Salzburg, stretching along the Salzach river in the shadow of ...
lie within of each other on the river Salzach in central Austria in an area with extensive salt deposits. Salzach
The Salzach (Austrian: saltsax ) is a river in Austria and Germany. It is in length and is a right tributary of the Inn, which eventually joins the Danube. Its drainage basin of comprises large parts of the Northern Limestone and Central E ...
literally means "salt river" and Salzburg "salt castle", both taking their names from the German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ger ...
word meaning salt. Hallstatt was the site of the world's first salt mine
Salt mining extracts natural salt deposits from underground. The mined salt is usually in the form of halite (commonly known as rock salt), and extracted from evaporite formations.
History
Before the advent of the modern internal combustio ...
. The town gave its name to the Hallstatt culture
The Hallstatt culture was the predominant Western Europe, Western and Central European Archaeological culture, culture of Late Bronze Age Europe, Bronze Age (Hallstatt A, Hallstatt B) from the 12th to 8th centuries BC and Early Iron Age Europe ...
that began mining for salt in the area in about 800 BC. Around 400 BC, the townsfolk, who had previously used pickaxe
A pickaxe, pick-axe, or pick is a generally T-shaped hand tool used for Leverage (mechanics), prying. Its head is typically metal, attached perpendicularly to a longer handle, traditionally made of wood, occasionally metal, and increasingly ...
s and shovel
A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore.
Most shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are usually made of ...
s, began open pan salt making
Open-pan salt making is a method of salt production wherein salt is extracted from brine using open pans.
Virtually all European domestic salt is obtained by solution-mining of underground salt formations, although some is still obtained by t ...
. During the first millennium BC, Celtic communities grew rich trading salt and salted meat
Salt-cured meat or salted meat is meat or fish preserved or Curing (food preservation), cured with salt. Salting (food), Salting, either with edible salt, dry salt or brine, was a common method of preserving meat until the middle of the 20th ce ...
to Ancient Greece
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
and Ancient Rome
In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 B ...
in exchange for wine and other luxuries.
The word ''salary
A salary is a form of periodic payment from an employer to an employee, which may be specified in an employment contract. It is contrasted with piece wages, where each job, hour or other unit is paid separately, rather than on a periodic basis.
...
'' comes from the Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word for salt. The reason for this is unknown; a persistent modern claim that the Roman Legion
The Roman legion ( la, legiō, ) was the largest military unit of the Roman army, composed of 5,200 infantry and 300 equites (cavalry) in the period of the Roman Republic (509 BC–27 BC) and of 5,600 infantry and 200 auxilia in the period of ...
s were sometimes paid in salt is baseless. The word ''salad'' literally means "salted", and comes from the ancient Roman practice of salting leaf vegetable
Leaf vegetables, also called leafy greens, pot herbs, vegetable greens, or simply greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. Leaf vegetables eaten raw in a salad can be called salad gre ...
s.
Wars have been fought over salt. Venice
Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400 ...
fought and won a war with Genoa
Genoa ( ; it, Genova ; lij, Zêna ). is the capital of the Italian region of Liguria and the List of cities in Italy, sixth-largest city in Italy. In 2015, 594,733 people lived within the city's administrative limits. As of the 2011 Italian ce ...
over the product, and it played an important part in the American Revolution
The American Revolution was an ideological and political revolution that occurred in British America between 1765 and 1791. The Americans in the Thirteen Colonies formed independent states that defeated the British in the American Revolut ...
. Cities on overland trade routes grew rich by levying duties
A duty (from "due" meaning "that which is owing"; fro, deu, did, past participle of ''devoir''; la, debere, debitum, whence "debt") is a commitment or expectation to perform some action in general or if certain circumstances arise. A duty may ...
,[ and towns like ]Liverpool
Liverpool is a city and metropolitan borough in Merseyside, England. With a population of in 2019, it is the 10th largest English district by population and its metropolitan area is the fifth largest in the United Kingdom, with a popul ...
flourished on the export of salt extracted from the salt mines of Cheshire
Cheshire ( ) is a ceremonial and historic county in North West England, bordered by Wales to the west, Merseyside and Greater Manchester to the north, Derbyshire to the east, and Staffordshire and Shropshire to the south. Cheshire's county t ...
. Various governments have at different times imposed salt taxes on their peoples. The voyages of Christopher Columbus
Christopher Columbus
* lij, Cristoffa C(or)ombo
* es, link=no, Cristóbal Colón
* pt, Cristóvão Colombo
* ca, Cristòfor (or )
* la, Christophorus Columbus. (; born between 25 August and 31 October 1451, died 20 May 1506) was a ...
are said to have been financed from salt production in southern Spain, and the oppressive salt tax in France was one of the causes of the French Revolution
The French Revolution ( ) was a period of radical political and societal change in France that began with the Estates General of 1789 and ended with the formation of the French Consulate in November 1799. Many of its ideas are considere ...
. After being repealed, this tax was reimposed by Napoleon
Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...
when he became emperor to pay for his foreign wars, and was not finally abolished until 1946. In 1930, Mahatma Gandhi
Mohandas Karamchand Gandhi (; ; 2 October 1869 – 30 January 1948), popularly known as Mahatma Gandhi, was an Indian lawyer, anti-colonial nationalist Quote: "... marks Gandhi as a hybrid cosmopolitan figure who transformed ... anti- ...
led a crowd of 100,000 protestors on the "Dandi March" or "Salt Satyagraha
The Salt March, also known as the Salt Satyagraha, Dandi March and the Dandi Satyagraha, was an act of nonviolent civil disobedience in colonial India led by Mahatma Gandhi. The twenty-four day march lasted from 12 March to 6 April 1930 as a di ...
", during which they made their own salt from the sea as a demonstration of their opposition to the colonial salt tax. This act of civil disobedience
Civil disobedience is the active, professed refusal of a citizen to obey certain laws, demands, orders or commands of a government (or any other authority). By some definitions, civil disobedience has to be nonviolent to be called "civil". Hen ...
inspired numerous Indians and transformed the Indian independence movement
The Indian independence movement was a series of historic events with the ultimate aim of ending British Raj, British rule in India. It lasted from 1857 to 1947.
The first nationalistic revolutionary movement for Indian independence emerged ...
from an elitist one with little popular support into a national struggle.
Chemistry
Salt is mostly sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
(NaCl). Sea salt
Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking, cosmetics and for preserving food. It is also called bay salt, solar salt, or simply salt. Like mined rock salt, production of sea sa ...
and mined salt may contain trace element
__NOTOC__
A trace element, also called minor element, is a chemical element whose concentration (or other measure of amount) is very low (a "trace amount"). They are classified into two groups: essential and non-essential. Essential trace elements ...
s. Mined salt is often refined. Salt crystals are translucent and cubic in shape; they normally appear white but impurities may give them a blue or purple tinge. When dissolved in water sodium chloride separates into Na+ and Cl− ions, and the solubility is 359 grams per litre. From cold solutions, salt crystallises as the dihydrate
In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...
NaCl·2H2O. Solutions of sodium chloride have very different properties from those of pure water; the freezing point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
is −21.12 °C (−6.02 °F) for 23.31 wt% of salt, and the boiling point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
The boiling point of a liquid varies depending upon the surrounding envir ...
of saturated salt solution is around 108.7 °C (227.7 °F).
Edible salt
Salt is essential to the health of humans and other animals, and it is one of the five basic taste sensations. Salt is used in many cuisines, and it is often found in salt shaker
Salt and pepper shakers or salt and pepper pots, of which the first item is normally called a salt cellar in British English, are condiment dispensers used in Western culture that are designed to allow diners to distribute grains of edible salt ...
s on diners' eating tables for their personal use on food. Salt is also an ingredient in many manufactured foodstuffs. Table salt is a refined salt containing about 97 to 99 percent sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
. Usually, anticaking agents
An anticaking agent is an additive placed in powdered or granulated materials, such as table salt or confectioneries, to prevent the formation of lumps (caking) and for easing packaging, transport, flowability, and consumption. Caking mechanisms d ...
such as sodium aluminosilicate
Sodium aluminosilicate refers to compounds which contain sodium, aluminium, silicon and oxygen, and which may also contain water. These include synthetic amorphous sodium aluminosilicate, a few naturally occurring minerals and synthetic zeolites. ...
or magnesium carbonate
Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.
Forms
The most common magnesium carbonate forms are ...
are added to make it free-flowing. Iodized salt
Iodised salt ( also spelled iodized salt) is table salt mixed with a minute amount of various salts of the element iodine. The ingestion of iodine prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is t ...
, containing potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...
, is widely available. Some people put a desiccant
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccant ...
, such as a few grains of uncooked rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
or a saltine cracker
A saltine or soda cracker is a thin, usually square cracker usually made from white flour, sometimes yeast (although many are yeast free), and baking soda, with most varieties lightly sprinkled with coarse salt. It has perforations over its surf ...
, in their salt shakers to absorb extra moisture and help break up salt clumps that may otherwise form.
Fortified table salt
Some table salt sold for consumption contains additives that address a variety of health concerns, especially in the developing world. The identities and amounts of additives vary from country to country. Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
is an important micronutrient for humans, and a deficiency
A deficiency is generally a lack of something. It may also refer to:
*A deficient number, in mathematics, a number ''n'' for which ''σ''(''n'') < 2''n''
* of the element can cause lowered production of thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
(hypothyroidism
Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as po ...
) and enlargement of the thyroid gland (endemic goitre
Endemic goiter is a type of goitre that is associated with dietary iodine deficiency.
Cause
Some inland areas where soil and water lacks in iodine compounds and consumption of marine foods is low are known for higher incidence of goitre. In such ...
) in adults or cretinism
Congenital iodine deficiency syndrome is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It ...
in children. Iodized salt has been used to correct these conditions since 1924 and consists of table salt mixed with a minute amount of potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...
, sodium iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I ...
, or sodium iodate
Sodium iodate ( Na I O3) is the sodium salt of iodic acid. Sodium iodate is an oxidizing agent. It has few uses.
Preparation
It can be prepared by the reacting a sodium-containing base such as sodium hydroxide with iodic acid, for example:
: ...
. A small amount of dextrose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
may also be added to stabilize the iodine. Iodine deficiency affects about two billion people around the world and is the leading preventable cause of mental retardation
Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation,Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signific ...
. Iodized table salt has significantly reduced disorders of iodine deficiency in countries where it is used.
The amount of iodine and the specific iodine compound added to salt varies. In the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, the Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) recommends 150 micrograms
In the metric system, a microgram or microgramme is a unit of mass equal to one millionth () of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom whe ...
of iodine per day for both men and women. US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the recommended iodine content of iodized salt is 10–22 ppm.
Sodium ferrocyanide
Sodium ferrocyanide is the sodium salt of the coordination compound of formula e(CN)6sup>4−. In its hydrous form, Na4Fe(CN)6 ( sodium ferrocyanide decahydrate), it is sometimes known as yellow prussiate of soda. It is a yellow crystalline ...
, also known as yellow of soda, is sometimes added to salt as an anticaking agent
An anticaking agent is an additive placed in powdered or granulated materials, such as table salt or confectioneries, to prevent the formation of lumps (caking) and for easing packaging, transport, flowability, and consumption. Caking mechanisms d ...
. Such anticaking agents have been added since at least 1911 when magnesium carbonate
Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.
Forms
The most common magnesium carbonate forms are ...
was first added to salt to make it flow more freely. The safety of sodium ferrocyanide as a food additive was found to be provisionally acceptable by the Committee on Toxicity
The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) is a UK independent scientific committee that provides advice to the Food Standards Agency, the Department of Health and other Government Departments and A ...
in 1988.[Discussions of the safety of sodium hexaferrocyanate in table salt](_blank)
. Hansard.millbanksystems.com (5 May 1993). Retrieved 7 July 2011. Other anticaking agents sometimes used include tricalcium phosphate
Tricalcium phosphate (sometimes abbreviated TCP) is a calcium salt of phosphoric acid with the chemical formula Ca3(PO4)2. It is also known as tribasic calcium phosphate and bone phosphate of lime (BPL). It is a white solid of low solubility. Mo ...
, calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
or magnesium carbonates, fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
salts (acid salt Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made duri ...
s), magnesium oxide
Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
, silicon dioxide
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
, calcium silicate
Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2. It is also referred to by the shortened trade name Cal-Sil or Calsil. It occurs naturally as the mineral larnite.
...
, sodium aluminosilicate and calcium aluminosilicate
Calcium aluminosilicate, an aluminosilicate compound with calcium cations, most typically has formula CaAl2Si2O8.
In minerals, as a feldspar, it can be found as anorthite, an end-member of the plagioclase
Plagioclase is a series of tecto ...
. Both the European Union and the United States Food and Drug Administration permitted the use of aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
in the latter two compounds.
In "doubly fortified salt", both iodide and iron salts are added. The latter alleviates iron deficiency anaemia
Iron-deficiency anemia is anemia caused by a lack of iron. Anemia is defined as a decrease in the number of red blood cells or the amount of hemoglobin in the blood. When onset is slow, symptoms are often vague such as feeling tired, weak, shor ...
, which interferes with the mental development of an estimated 40% of infants in the developing world. A typical iron source is ferrous fumarate
Iron(II) fumarate, also known as ferrous fumarate, is the iron(II) salt of fumaric acid, occurring as a reddish-orange powder, used to supplement iron intake. It has the chemical formula . Pure ferrous fumarate has an iron content of 32.87%, the ...
. Another additive, especially important for pregnant
Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occur ...
women, is folic acid
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
(vitamin B9), which gives the table salt a yellow color. Folic acid helps prevent neural tube defect
Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation, specialized cells on the dorsal side of the embryo ...
s and anaemia, which affect young mothers, especially in developing countries.
A lack of fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
in the diet is the cause of a greatly increased incidence of dental caries
Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complicatio ...
. Fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
salts can be added to table salt with the goal of reducing tooth decay, especially in countries that have not benefited from fluoridated toothpastes and fluoridated water. The practice is more common in some European countries where water fluoridation
Water fluoridation is the controlled adjustment of fluoride to a public water supply solely to reduce tooth decay. Fluoridated water contains fluoride at a level that is effective for preventing cavities; this can occur naturally or by adding ...
is not carried out. In France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, 35% of the table salt sold contains added sodium fluoride
Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. I ...
.
Other kinds
Unrefined sea salt
Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking, cosmetics and for preserving food. It is also called bay salt, solar salt, or simply salt. Like mined rock salt, production of sea sa ...
contains small amounts of magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
and calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
halides
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...
and sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...
s, traces of algal products, salt-resistant bacteria and sediment particles. The calcium and magnesium salts confer a faintly bitter overtone, and they make unrefined sea salt hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...
(i.e., it gradually absorbs moisture from air if stored uncovered). Algal products contribute a mildly "fishy" or "sea-air" odour, the latter from organobromine compounds. Sediments, the proportion of which varies with the source, give the salt a dull grey appearance. Since taste and aroma compounds are often detectable by humans in minute concentrations, sea salt may have a more complex flavor than pure sodium chloride when sprinkled on top of food. When salt is added during cooking however, these flavors would likely be overwhelmed by those of the food ingredients. The refined salt industry cites scientific studies saying that raw sea and rock salts do not contain enough iodine
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
salts to prevent iodine deficiency diseases.
Salts have diverse mineralities depending on their source, giving each one a unique flavour. Fleur de sel
''Fleur de sel'' ("flower of salt" in French; ) or ''flor de sal'' (also "flower of salt" in Portuguese, Spanish and Catalan) is a salt that forms as a thin, delicate crust on the surface of seawater as it evaporates. ''Fleur de sel'' has been c ...
, a natural sea salt from the surface of evaporating brine in salt pans, has a distinctive flavour varying with its source. In traditional Korean cuisine
Korean cuisine has evolved through centuries of social and political change. Originating from ancient agricultural and nomadic traditions in Korea and southern Manchuria, Korean cuisine reflects a complex interaction of the natural envi ...
, so-called " bamboo salt" is prepared by roasting salt in a bamboo
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud, and has been claimed to increase the anticlastogenic and antimutagenic Antimutagens are the agents that interfere with the mutagenicity of a substance. The interference can be in the form of prevention of the transformation of a promutagenic compound into actual active mutagen, inactivation, or otherwise the preventio ...
properties of doenjang
''Doenjang''
* (; "thick sauce") or soybean paste is a type of fermented bean paste made entirely of soybean and brine. It is also a byproduct of soup soy sauce production. It is sometimes used as a relish.
History
The earliest soybean fe ...
(a fermented bean paste).
Kosher or kitchen salt has a larger grain size than table salt and is used in cooking. It can be useful for brining
In food processing, brining is treating food with brine or coarse salt which preserves and seasons the food while enhancing tenderness and flavor with additions such as herbs, spices, sugar, caramel or vinegar. Meat and fish are typically brined ...
, bread or pretzel
A pretzel (), from German pronunciation, standard german: Breze(l) ( and French / Alsatian: ''Bretzel'') is a type of baked bread made from dough that is commonly shaped into a knot. The traditional pretzel shape is a distinctive symmetrical ...
making and as a scrubbing agent when combined with oil.
Pickling salt
Pickling salt is a salt that is used mainly for canning and manufacturing pickles. It is sodium chloride, as is table salt, but unlike most brands of table salt, it does not contain iodine or any anti caking products added. A widely circulated ...
is made of ultra-fine grains to speed dissolving to make brine
Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for br ...
.
Salt in food
Salt is present in most food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
s, but in naturally occurring foodstuffs such as meats, vegetables and fruit, it is present in very small quantities. It is often added to processed foods (such as canned foods
Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...
and especially salted foods
Salting is the preservation of food with dry edible salt. , pickled foods
Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is calle ...
, and snack food
A snack is a small portion of food generally Eating, eaten between meals. Snacks come in a variety of forms including packaged snack foods and other processed foods, as well as items made from fresh ingredients at home.
Traditionally, snack ...
s or other convenience food
Convenience food, also called tertiary processed food, is food that is commercially prepared (often through processing) to optimise ease of consumption. Such food is usually ready to eat without further preparation. It may also be easily por ...
s), where it functions as both a preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...
and a flavoring
A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the gusta ...
. Dairy salt
Dairy salt is a culinary salt (sodium chloride) product used in the preparation of butter and cheese products that serves to add flavor and act as a food preservative. Dairy salt can vary in terms of quality and purity, with purer varieties be ...
is used in the preparation of butter and cheese products. As a flavoring, salt enhances the taste of other foods by suppressing the bitterness of those foods making them more palatable and relatively sweeter.
Before the advent of electrically powered refrigeration
The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
, salting was one of the main methods of food preservation
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit ...
. Thus, herring
Herring are forage fish, mostly belonging to the family of Clupeidae.
Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...
contains 67 mg sodium per 100 g, while kipper
A kipper is a whole herring, a small, oily fish, that has been split in a butterfly fashion from tail to head along the dorsal ridge, gutted, salted or pickled, and cold-smoked over smouldering wood chips (typically oak).
In the United Ki ...
, its preserved form, contains 990 mg. Similarly, pork
Pork is the culinary name for the meat of the domestic pig (''Sus domesticus''). It is the most commonly consumed meat worldwide, with evidence of pig husbandry dating back to 5000 BCE.
Pork is eaten both freshly cooked and preserved; ...
typically contains 63 mg while bacon
Bacon is a type of salt-cured pork made from various cuts, typically the belly or less fatty parts of the back. It is eaten as a side dish (particularly in breakfasts), used as a central ingredient (e.g., the bacon, lettuce, and tomato sand ...
contains 1,480 mg, and potato
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern Unit ...
es contain 7 mg but potato crisp
A potato chip (North American English; often just chip) or crisp (British and Irish English) is a thin slice of potato that has been either deep fried, baked, or air fried until crunchy. They are commonly served as a snack, side dish, or ap ...
s 800 mg per 100 g. Salt is also used extensively in cooking as a flavoring, and cooking techniques such as with salt crusts and brining
In food processing, brining is treating food with brine or coarse salt which preserves and seasons the food while enhancing tenderness and flavor with additions such as herbs, spices, sugar, caramel or vinegar. Meat and fish are typically brined ...
. The main sources of salt in the Western diet, apart from direct use of sodium chloride, are bread and cereal products, meat products and milk and dairy products.
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.
Biology of salt taste
Human salt taste is detected by sodium taste receptors present in taste bud cells on the tongue. Human sensory taste testing studies have shown that Proteolysis, proteolyzed forms of epithelial sodium channel (ENaC) function as the human salt taste receptor.
Sodium consumption and health
Table salt is made up of just under 40% sodium by weight, so a 6g serving (1teaspoon) contains about 2,400mg of sodium. Sodium serves a vital purpose in the human body: via its role as an electrolyte, it helps nerves and muscles to function correctly, and it is one factor involved in the autoregulation, osmotic regulation of water content in body organs (fluid balance). Most of the sodium in the Western diet comes from salt. The habitual salt intake in many Western countries is about 10 g per day, and it is higher than that in many countries in Eastern Europe and Asia.[ The high level of sodium in many processed foods has a major impact on the total amount consumed. In the United States, 75% of the sodium eaten comes from processed and restaurant foods, 11% from cooking and table use and the rest from what is found naturally in foodstuffs.
Because consuming too much sodium increases risk of cardiovascular diseases,][ health organizations generally recommend that people reduce their dietary intake of salt.] High sodium intake is associated with a greater risk of stroke, total cardiovascular disease and kidney disease. A reduction in sodium intake by 1,000 mg per day may reduce cardiovascular disease by about 30 percent.[ In adults and children with no acute illness, a decrease in the intake of sodium from the typical high levels reduces blood pressure.] A low sodium diet results in a greater improvement in blood pressure in people with hypertension
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
.
The World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
recommends that adults should consume less than 2,000 mg of sodium (which is contained in 5g of salt) per day. Guidelines by the United States recommend that people with hypertension, African Americans, and middle-aged and older adults should limit consumption to no more than 1,500 mg of sodium per day and meet the potassium recommendation of 4,700 mg/day with a healthy diet of fruits and vegetables.
While reduction of sodium intake to less than 2,300 mg per day is recommended by developed countries,[ one review recommended that sodium intake be reduced to at least 1,200 mg (contained in 3g of salt) per day, as a further reduction in salt intake the greater the fall in systolic blood pressure for all age groups and ethnicities.][ Another review indicated that there is inconsistent/insufficient evidence to conclude that reducing sodium intake to lower than 2,300 mg per day is either beneficial or harmful.
Evidence shows a more complicated relationship between salt and cardiovascular disease. "Mortality caused by levels of salt the association between sodium consumption and cardiovascular disease or mortality is U-shaped, with increased risk at both high and low sodium intake."] The findings showed that increased mortality from excessive salt intake was primarily associated with individuals with hypertension. The levels of increased mortality among those with restricted salt intake appeared to be similar regardless of blood pressure. This evidence shows that while those with hypertension should primarily focus on reducing sodium to recommended levels, all groups should seek to maintain a healthy level of sodium intake of between 4 and 5 grams (equivalent to 10-13 g salt) a day.
One of the two most prominent dietary risks for disability in the world are diets high in sodium.
Non-dietary uses
Only about 6% of the salt manufactured in the world is used in food. Of the remainder, 12% is used in water conditioning processes, 8% goes for de-icing highways and 6% is used in agriculture.[ Sodium chloride is one of the largest volume inorganic raw materials. Its major chemical products are ]caustic soda
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alka ...
and chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
. These are used in the manufacture of PVC, paper pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw mate ...
and many other inorganic and organic compounds. Salt is also used as a Flux (metallurgy), flux in the production of aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
. For this purpose, a layer of melted salt floats on top of the molten metal and removes iron and other metal contaminants. It is also used in the manufacture of soaps and glycerine, where it is used to Saponification, saponify fats. As an emulsifier, salt is used in the manufacture of synthetic rubber, and another use is in the firing of pottery, when salt added to the furnace vaporises before condensing onto the surface of the ceramic material, forming a strong Ceramic glaze, glaze.
When drilling through loose materials such as sand or gravel, salt may be added to the drilling fluid to provide a stable "wall" to prevent the hole collapsing. There are many other processes in which salt is involved. These include its use as a mordant in textile dying, to regenerate resins in water softening, for the Tanning (leather), tanning of hides, the preservation of meat and fish and the canning
Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...
of meat and vegetables.
Production
Food-grade salt accounts for only a small part of salt production in Developed country, industrialized countries (7% in Europe), although worldwide, food uses account for 17.5% of total production.
In 2018, total world production of salt was 300 million tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s, the top six producers being China (68 million), the United States (42 million), India (29 million), Germany (13 million), Canada (13 million) and Australia (12 million).
The manufacture of salt is one of the oldest chemical industries. A major source of salt is seawater, which has a salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
of approximately 3.5%.[ This means that there are about of sea salt, dissolved salts, predominantly sodium () and chloride () ions, per kilogram (2.2 lbs) of water. The world's oceans are a virtually inexhaustible source of salt, and this abundance of supply means that reserves have not been calculated.][ The evaporation of seawater is the production method of choice in marine countries with high evaporation and low precipitation rates. Salt evaporation ponds are filled from the ocean and salt crystals can be harvested as the water dries up. Sometimes these ponds have vivid colours, as some species of algae and other micro-organisms thrive in conditions of high salinity.
Elsewhere, salt is extracted from the vast sedimentary deposits which have been laid down over the millennia from the evaporation of seas and lakes. These sources are either salt mine, mined directly, producing rock salt, or are extracted by pumping water into the deposit. In either case, the salt may be purified by mechanical evaporation of brine. Traditionally, purification was achieved in Open pan salt making, shallow open pans that were heated to accelerate evaporation. Vacuum-based methods are also employed. The raw salt is refined by treatment with chemicals that precipitate most impurities (largely magnesium and calcium salts). Multiple stages of evaporation are then applied. Some salt is produced using the Alberger process, which involves vacuum pan evaporation combined with the seeding of the solution with cubic crystals, and produces a grainy-type flake. The Ayoreo people, Ayoreo, an indigenous group from the Paraguayan Gran Chaco people, Chaco, obtain their salt from the ash produced by burning the timber of the Indian salt tree (''Maytenus vitis-idaea'') and other trees.
One of the largest salt mining operations in the world is at the Khewra Salt Mine in Pakistan. The mine has nineteen storeys, eleven of which are underground, and of passages. The salt is dug out by the room and pillar method, where about half the material is left in place to support the upper levels. Extraction of Himalayan salt is expected to last 350 years at the present rate of extraction of around 385,000 tons per annum.]
In religion
Salt has long held an important place in religion and culture. At the time of Historical Vedic religion, Brahmanic sacrifices, in Hittites, Hittite rituals and during festivals held by Semitic people, Semites and Greeks at the time of the new moon, salt was thrown into a fire where it produced crackling noises. The ancient Egyptians, Greeks and Romans invoked their gods with offerings of salt and water and some people think this to be the origin of Holy Water in the Christian faith. In Aztec mythology, Huixtocihuatl was a fertility goddess who presided over salt and salt water.
Salt is considered to be a very auspicious substance in Hinduism and is used in particular religious ceremonies like house-warmings and weddings. In Jainism, devotees lay an offering of raw rice with a pinch of salt before a deity to signify their devotion and salt is sprinkled on a person's cremated remains before the ashes are buried. Salt is believed to ward off evil spirits in Mahayana Buddhism, Mahayana Buddhist tradition, and when returning home from a funeral, a pinch of salt is thrown over the left shoulder as this prevents evil spirits from entering the house. In Shinto, is used for ritual purification of locations and people (harae, specifically shubatsu), and small piles of salt are placed in dishes by the entrance of establishments for the twofold purposes of warding off evil and attracting patrons.
In the Hebrew Bible, there are thirty-five verses which Salt in the Bible, mention salt. One of these mentions Lot's wife, who was turned into a pillar of salt when she looked back at the cities of Sodom and Gomorrah (Book of Genesis, Genesis 19:26) as they were destroyed. When the judge Abimelech (Judges), Abimelech destroyed the city of Shechem
Shechem ( ), also spelled Sichem ( ; he, שְׁכֶם, ''Šəḵem''; ; grc, Συχέμ, Sykhém; Samaritan Hebrew: , ), was a Canaanite and Israelite city mentioned in the Amarna Letters, later appearing in the Hebrew Bible as the first cap ...
, he is said to have "salting the earth, sown salt on it," probably as a curse on anyone who would re-inhabit it (Judges 9:45). The Book of Job contains the first mention of salt as a condiment. "Can that which is unsavoury be eaten without salt? or is there any taste in the white of an egg?" (Job 6:6).[ In the New Testament, six verses mention salt. In the Sermon on the Mount, Jesus referred to his followers as the "Salt and Light, salt of the earth". Paul the Apostle, The apostle Paul also encouraged Christians to "let your conversation be always full of grace, seasoned with salt" (Colossians 4:6).][ Salt is mandatory in the rite of the Tridentine Mass.][s:Catholic Encyclopedia (1913)/Salt] Salt is used in the third item (which includes an Exorcism) of the Celtic Consecration (''cf.'' Gallican Rite) that is employed in the consecration of a church. Salt may be added to the water "where it is customary" in the Roman Catholic rite of Holy water.[
In Judaism, it is recommended to have either a salty bread or to add salt to the bread if this bread is unsalted when doing Kiddush for Shabbat. It is customary to spread some salt over the bread or to dip the bread in a little salt when passing the bread around the table after the Kiddush. To preserve the covenant between their people and God, Jews dip the Sabbath bread in salt.]
In Wicca, salt is symbolic of the element Earth. It is also believed to cleanse an area of harmful or negative energies. A dish of salt and a dish of water are almost always present on an altar, and salt is used in a wide variety of rituals and ceremonies.
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{{Good article
Edible salt,
Food additives
Sodium minerals
Objects believed to protect from evil
Food powders