When commercially available table salt is obtained, 1–3% other salts remain in the rock salt and in the sea salt, and in the case of untreated sea salt, a residual moisture of up to 5% water remains. Mainly purified, refined salt is on the market. Small amounts of other substances can be added to improve technical properties ( hygroscopicity , flowability ) or to prevent deficiency symptoms .
The salt production is by most civilizations of antiquity testified. It can be assumed that table salt had a place in people's culture very early on. The Sumerians and Babylonians used salts to preserve food.
In the Celtic-Germanic area there was a large-scale production of salt from sea water from the Bronze Age.
Salt was in great demand and rare in certain regions. Already in prehistoric times it was transported on salt roads from the places of manufacture to the low-salt regions. More articles were transported on the resulting salt roads. This made the salt routes into important trade routes. Examples are the old salt route of the Hanseatic League from Lüneburg to Lübeck with a length of 127 kilometers or the salt route from Hall in Tirol to Matrei am Brenner .
How valuable table salt was can be seen from the term “white gold”. The word “salary” comes from the payment of wages or salaries in the form of salt.
"The price stability and regulated supply made it possible for the Romans to use salt as a means of payment, for example the Roman legionaries were sometimes paid with it."
Salt played an important role in the history of taxation in many countries , and many governments strictly enforced the profitable salt production and trade monopoly, such as the Egypt of the Ptolemies and the Empire of the Seleucids . In the Middle Ages and later, large sums of money had to be paid for salt. Many cities became wealthy metropolises through the transport of table salt and trade (see salt trade , salt monopoly , salt tax ). Lüneburg was the primary salt supplier to the Hanseatic League , in whose northern European sphere of influence curing was the most important preservation technique for fish, meat and cabbage.
It is not uncommon for farmers to be able to afford meat meals in moderation despite their own slaughter, because salt was necessary for curing and thus for shelf life. In 1648 there was the "Salt Uprising in Moscow" because a salt tax tripled the price of salt.
In the German-speaking countries, table salt only became affordable when the salt layers of the Zechstein Sea, several hundred meters thick and 250 million years old , could be mined.
“In Staßfurt, deep drilling began in the spring of 1839; at 826 feet below the surface or 605 feet below sea level, the rock salt deposit was hit, which has been traced to a depth of 1,851 feet. [...] The production of the Staßfurt rock salt mine is currently estimated at half a million centners annually; the debit is on the rise. Any amount can be promoted and a shortage of salt in Prussia under any political conditions is no longer possible. "
Countries and cities that owned the salt shelf monitored their right to trade in salt within its scope. The salt trade in Germany was subject to the salt tax until 1993 and was an important monopoly. In China, the trade in salt and its price was regulated by the state until 2017. Only the China National Salt Industry Corporation was authorized to sell table salt in China.
Salt can be exempt from the salt tax by adding aromas (such as smoked salt ) or adding other substances (such as road salt ). In the past, the salt barrel at the table was the container for individual post-salting, but the ability to dose was refined with the salt shaker. With the grainy table salts that are in vogue today, the salt mill became necessary. The finer the salt, the better and faster it dissolves and spreads in the dish. This results in the taste properties of special forms of table salt, such as the fleur de sel , which mainly consist of sodium chloride.
In the oldest type of salt extraction, the water from naturally salty surface waters, mostly seawater , is directed into salt gardens (shallow basins), where it evaporates when exposed to sunlight. All the ions in the sea water crystallize one after the other in the form of ionic compounds according to their solubilities . In the process, calcium sulfate (gypsum) and then sodium chloride precipitate. The sodium chloride used as table salt is skimmed off and dried before the water completely evaporates. Slight admixtures of other salts and impurities, for example due to clay , cannot be prevented. Trace elements from sea water would only be contained in this sea salt if it had completely evaporated and dried out , which, however, led to an undesirable aftertaste and increased pollution.
Today around 20% of the world's consumption is derived from seawater. Sea salt is still extracted on European coasts, such as the Algarve , Brittany , Camargue , Tuscany and Croatia. There are deposits in the US, South America and Africa, where salt in the open pit of geologically young dried salt lakes is encouraged. These deposits are not covered by thick layers of rock like those in northern and central Germany, but also contain smaller amounts of salt. In the desalination of sea water , all salts dissolved in the sea water are produced as by-products.
Rock salt from underground salt deposits can be extracted in two ways: by drilling into and removing the salt from the deposit with the help of water from the surface of the earth ( leaching ) or by underground mining . In Central Germany, mining is done mechanically with the help of special milling machines and other heavy equipment. In the Berchtesgaden salt mine, on the other hand, what is known as wet mining takes place, i.e. there, too, the salt (in this case strongly mixed with other rock ) is released from the mountain with the help of water. In the case of brine-out and wet mining, the table salt is obtained by evaporating the water from the salt solution ( brine ) extracted ( evaporated salt ). Mechanically degraded salt is first dissolved in water and then crystallized out by concentration / concentration of the brine in order to separate it from accompanying substances and impurities ( recrystallization ).
- With the Indians of South America and in some regions of West and Central Africa, a salty product is obtained by washing out vegetable ash. This product also contains large amounts of potassium chloride .
- In South America and West Africa around Lake Chad, salty soil is washed out, filtered and boiled down. A method that is also used in Thailand and New Guinea.
- On the North Sea coast, in the Netherlands, Northern Germany and Denmark, peat was found that was flooded by seawater. This was washed out and filtered, and the concentrated brine was concentrated in boiling pans. This gave the Halligen their name, from Old High German "Hall" = "salt". The process has been documented since the Middle Ages and is still demonstrated on Læsø (Denmark) as a tourist attraction.
- The salt, which was widespread in the West African caravan trade in the 17th and 18th centuries, was obtained primarily from salty, shallow groundwater in the Sahara, which was drawn from wells.
The share of table salt production in Germany (440,000 t) is around three percent of total world production.
The presence of table salt reduces the solubility of the organic seasonings and thus increases their perception in the taste. A small amount of salt in bread or roll dough stabilizes the adhesive protein ( gluten ).
Vegetables are usually cooked in salted water. Salt opens up the cell walls through osmosis , which shortens the cooking time, and important ingredients are retained. Exceptions are legumes , which are always salted after cooking because the cooking time in salt water significantly extended. When baking fish, poultry, or meat in a salt crust, salt isolates the food, causing it to cook in its own juice. Salt controls the development of enzymes during dough preparation and enables controlled fermentation.
In addition to individual seasoning, table salt is indispensable in the production of meat and sausage products, bread and cheese.
By far the largest part of salt intake occurs through processed foods, less through direct seasoning, which can vary greatly from person to person. In the GDA labeling system (list of ingredients on the packaging of processed foods), the salt content is specified in the form of salt equivalents . For example, it says 1 gram of sodium and not 2.5 grams of salt.
In the Middle Ages, table salt was also used for the external treatment of ulcers and wounds, as it was seen here as astringent, cleansing and soothing.
The daily salt requirement of a person is between a minimum of 3 to 6 grams and a maximum of 16 to 20 grams of table salt, depending on the individual and the climatic environment. The World Health Organization recommends a salt intake of 5 grams for adults. This results in an annual consumption depending on the environment and the assumed daily intake of 1.8 to 6.4 kilograms.
In ancient Rome, Pliny the Elder and Lucius J. Columella estimated the amount of table salt used daily in the kitchen to be around 25 grams per person. The economic historian Hans-Heinrich Bass puts the average salt consumption in Germany (based on Prussia ) in the first half of the 19th century at 22 grams per person. The salt has served as a condiment and preferably as a preservative (meat, cabbage, beans).
In the late 1980s, including wasted salt in the kitchen and ready-to-cook products, the average daily consumption of the average US citizen was estimated to be around 135 grams of salt.
When specifying the average consumption per person, it must be taken into account that around half of the table salt used is lost, for example through cooking water or food waste.
A distinction is made between rock salt and (predominantly today) evaporated salt. Himalayan salt has a reddish color due to its iron oxide content. Sea salt is obtained from sea water. Indian kala namak (black salt) for Ayurvedic cuisine is of volcanic origin.
Table salt is the most widely consumed mineral in the human diet. In dissolved form, table salt is in the form of positively charged sodium and negatively charged chloride ions , which have their own roles in the water balance , the nervous system , digestion and bone structure . An adult's body contains around 150 to 300 grams of table salt and needs one to three grams a day to compensate for the loss through sweat and excretion. With some illnesses or heavy sweating, the daily loss of salt can reach 20 grams.
Since it used to be difficult for humans to get sufficient amounts of table salt, salt intake is rewarded with a release of dopamine . The genes responsible for the appetite for salt have been linked to drug addiction ( opiates and cocaine ).
high blood pressure
Above-average salt consumption has been blamed for high blood pressure since the 1970s and a low-salt diet was recommended as a preventive measure. There are indications that the "salt sensitivity" depends on many different factors such as genetic predisposition, age or BMI . Findings from the Mars-500 project , which was carried out on six test subjects , show that a reduction in salt consumption lowers blood pressure. Reducing the average amount consumed in Germany from twelve to six grams has about the same effect as antihypertensive agents.
“The interplay between genetics and the environment, the research area of the President of the American Heart Association [ AHA ] is being understood better and better, an interaction that is of central importance for [blood] pressure regulation [...] Too much table salt in food lowers blood pressure throughout the population increase. The average daily consumption of table salt, as a current survey by the AHA and the American Stroke Association (ASA) has shown, is around 3.4 g sodium (corresponding to 8.6 g table salt). That is more than twice the recommended daily dose of 1.5 g sodium (equivalent to 3.8 g table salt). The reason that most people do not rate their salt consumption as high is that they only actively add salt to a small part. 75% of the table salt consumed comes from ready meals and industrially produced foods. "
At a conference of the American Heart Association in New Orleans, epidemiologists showed that around 2.3 million people worldwide die each year from cardiac events based on excessive salt intake. In industrialized countries as well as in emerging and developing countries, the consumption of table salt is increasing.
In a study on 31 pregnant women it was observed that salt consumption in conjunction with the changed hormone balance was able to lower blood pressure.
Inflammation and dementia
High salt consumption led to cognitive deficits in mice , as reported by researchers from the Weill Cornell Medical College in the journal Nature Neuroscience . It appears that foods that contain salty food increase the number of special T-helper cells in the small intestine . These release the inflammatory signaling substance interleukin-17 , which then accumulates in the blood plasma and disrupts the function of the endothelial cells . These cells line the inside of the blood vessels and play an important role in regulating blood pressure , for example .
Acute over- or underdosing
The amount of salt in the human body is regulated by hormones and remains almost constant. If the salt content is too high, excess sodium chloride is excreted through fluid expulsion ( saluresis ), which is associated with a considerable loss of water. The result is a feeling of thirst . A permanently high salt intake increases the amount of water in the body and thus the weight and can damage the kidney function. Consumption of less than two grams per day has a negative effect, as the low salt concentration in the person's body stops any feeling of thirst and thus leads to dehydration.
There are known cases in which excessive sudden salt consumption has been life-threatening. For example, a four-year-old girl died in 2005 from a forced intake of 32 grams of table salt. In a comparative study of children of the same age, it was found that even a fraction of this amount of salt was not consumed voluntarily by a single child. The LD 50 for table salt is 3 g per kilogram of body weight. It is unlikely to accidentally ingest this amount.
Measuring device in the mouth
In May 2018, a group led by Woon-Hong Yeo from the Georgia Institute of Technology , USA presented a measuring device to be worn in the palate of the upper jaw with braces, which measures the salt concentration in porridge while eating and transmits it to a smartphone, for example.
Various additives to table salt are possible in order to change application-related or nutritional properties.
Improvement of the flowability
Salt is due to naturally contained in small amounts of other salts such as magnesium chloride , hygroscopic . As a result, it becomes moist and clumped in the air, so that it can no longer be finely dosed. Calcium carbonate (lime), magnesium carbonate , aluminum oxide , silicates or potassium hexacyanidoferrate (II) are added as a flow aid to improve the flowability . The poorly soluble calcium and magnesium carbonate causes the cloudiness when the table salt is dissolved in water. Well-flowing table salt was developed in 1911 by the US salt manufacturer Morton Salt .
To prevent goiter and to prevent iodine deficiency , sodium iodate or potassium iodate can be added to the table salt . In Germany, iodized salt contains 15 to 25 mg of iodine per kilogram. Iodate is used because iodide is not stable under the influence of water and atmospheric oxygen and converts easily to iodine. In the USA, however, potassium and sodium iodide are used, which are protected from oxidation by stabilizers such as thiosulfates .
In Austria iodized table salt contains 15 to 20 mg iodine / kg salt.
In the EU, the best-before date is required for iodized table salt, but not for untreated salt.
Small amounts of sodium fluoride or potassium fluoride are added to prevent caries . This practice first appeared in Switzerland in the 1950s. In 1955, the canton of Zurich was the first to introduce fluoridated table salt, and other cantons followed. For some years now, fluoridated table salt has held a stable market share of around 80 percent in Switzerland. Since 1983 the dosage has been around 250 milligrams of fluoride ions per kilogram of table salt.
Other countries followed the Swiss example only hesitantly. There has been fluoridated table salt in France since 1983, followed by Jamaica and Costa Rica . In 1991 the sale of an iodized salt with fluoride produced in France was approved in Germany on the basis of special permits. Production in Germany was approved the next year. In 2006, fluoridated table salt was recommended as a standard measure for caries prophylaxis in the "Guideline on fluoridation measures" of the "Dental Central Quality Assurance", which was developed in consultation with other scientific societies and specialist institutions. In the same year, the European Parliament approved the fortification of foods with fluoride. This cleared the way for table salt fluoridation in all EU countries.
In 2011, the market share of fluoride-mixed salt in total table salt sales in household containers in Germany was 68 percent. It contains 250 mg fluoride / kg table salt in the form of sodium or potassium fluoride. The information center for caries prophylaxis sees this as a simple and inexpensive way to better prevent caries. Fluoridated table salt acts locally before ingestion through direct contact with the tooth surface. It increases the fluoride concentration in saliva and protects against tooth decay when eating. The caries-preventive effect of fluoridated table salt has meanwhile been proven by numerous studies.
Curing salt is table salt with an addition of 0.4% to 0.5% sodium nitrite . This is intended to achieve the desired “reddening” when curing meat. "Reddening" is understood to mean the formation of the typical, heat-stable red color of cured meat products. The color of meat is mainly determined by the color of the myoglobin in the muscle. When certain diatomic molecules (e.g. oxygen, carbon monoxide or nitrogen oxide) attach to the central iron atom of myoglobin, it changes color. If untreated meat is heated, the central iron atom oxidizes (from Fe 2+ to Fe 3+ ) and the color changes from red to gray-brown. If nitrite is added to the meat, which can be done in the form of “nitrite curing salt”, under the right conditions nitric oxide (NO) is formed in the meat , which combines with the myoglobin to form heat-stable nitrosomyoglobin, thus maintaining the more “appetizing” color.
There are essentially two theories about the chemical processes involved in reddening meat. On the one hand the purely chemical and on the other hand the biochemical reaction path. In both approaches, the myoglobin is oxidized to metmyoglobin in the first step under the action of nitrite . In the second step, nitric oxide attaches to the metmyoglobin and forms nitrosometmyoglobin. This in turn is ultimately reduced to nitrosomyoglobin by enzymes or temperatures above 75 ° C.
The formation of the curing color depends on the temperature, the time and the pH value at which the reaction takes place. The reaction proceeds faster at lower pH values than at higher pH values. The addition of reddening agents accelerates the reddening and has a positive effect on the color stability of the finished products.
The German Nutrition Society assumes that there is an insufficient supply of folic acid in Germany. For this reason, folic acid is added to some types of table salt. Their yellowish color is characteristic. When using it, it should be noted that folic acid is not boil-proof and table salt with folic acid should only be added after cooking.
The addition of spices and other flavorings leads to the extensive range of seasoning salts . On the one hand, the herbs and spices are supposed to give the salt a "taste", on the other hand the addition of salt has a stabilizing effect on the spices, as with garlic salt .
“Ur-Salt” and refining
There are numerous esoteric authors who speak out against the practice of adding additives to natural salt or of removing contaminants from the salt through certain treatment processes. A distinction is made between refined and allegedly ancient salt , such as Himalayan salt . The positive health effects would be diminished or even lost during refining , while the negative health effects would increase. However, like the refined salt, the so-called primeval salt consists almost exclusively of sodium chloride . With an intake of a maximum of two teaspoons of salt a day, all other ingredients are present in too small amounts to have any physiological effects. The basis of such considerations is the assumption of immaterial properties associated with the ancient salt. However, there are no scientific studies on the health benefits of the primal salt .
Places associated with (table) salt often have the component salt , the Middle High German word Hall or similar references in their names. examples are
- Outside the German-speaking area
The name of the Salzkammergut region is historically based on imperial special rights for the raw material extracted here - in the south of Upper Austria.
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