Sodium nitrite

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Sodium nitrite
Sodium nitrite.svg
The nitrite anion (space-filling model) Nitrite-3D-vdW.png
The nitrite anion (space-filling model)
The sodium cation Sodium-3D.png
The sodium cation
Natriumnitrit Elementarzelle.png
Unit cell of sodium nitrite under standard conditions
Sodium nitrite crystals.jpg
Names
IUPAC name
Sodium nitrite
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.687 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-555-9
E number E250 (preservatives)
KEGG
PubChem CID
RTECS number
  • RA1225000
UNII
UN number 1500 3287
  • InChI=1S/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1 Yes check.svgY
    Key: LPXPTNMVRIOKMN-UHFFFAOYSA-M Yes check.svgY
  • InChI=1/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
    Key: LPXPTNMVRIOKMN-REWHXWOFAO
  • N(=O)[O-].[Na+]
Properties
NaNO2
Molar mass 68.9953 g/mol
Appearancewhite or slightly yellowish crystalline solid
Density 2.168 g/cm3
Melting point 271 °C (520 °F; 544 K) (decomposes at 320 °C)
  • 71.4 g/(100 mL) (0 °C)
  • 84.8 g/(100 mL) (25 °C)
  • 160 g/(100 mL) (100 °C)
Solubility in methanol 4.4 g/(100 mL)
Solubility in ethanol Soluble
Solubility in diethyl ether 0.3 g/(100 mL)
Solubility in ammonia Very soluble
Acidity (pKa)~9
−14.5·10−6 cm3/mol
1.65
Structure [1]
Orthorhombic
Im2m
a = 3.5653(8) Å, b = 5.5728(7) Å, c = 5.3846(13) Å
2
Thermochemistry
Std molar
entropy
(S298)
106 J/(mol·K)
−359 kJ/mol [2]
−295 kJ/mol
Pharmacology
V03AB08 ( WHO )
Hazards
GHS labelling: [3]
GHS-pictogram-rondflam.svg GHS-pictogram-skull.svg GHS-pictogram-pollu.svg
Danger
H272, H301, H319, H400
P220, P273, P301+P310, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
3
0
1
OX
489 °C (912 °F; 762 K)
Lethal dose or concentration (LD, LC):
180 mg/kg (rats, oral)
Safety data sheet (SDS) "Sodium nitrite". Safety Data Sheet. Sigma-Aldrich. 28 December 2022.
Related compounds
Other anions
Sodium nitrate
Other cations
Related compounds
Nitrous acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium nitrite is an inorganic compound with the chemical formula Na N O 2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products. [4]

Uses

Industrial chemistry

The main use of sodium nitrite is for the industrial production of organonitrogen compounds. It is a reagent for conversion of amines into diazo compounds, which are key precursors to many dyes, such as diazo dyes. Nitroso compounds are produced from nitrites. These are used in the rubber industry. [4]

It is used in a variety of metallurgical applications, for phosphatizing and detinning. [4]

Sodium nitrite is an effective corrosion inhibitor and is used as an additive in industrial greases, [5] as an aqueous solution in closed loop cooling systems, and in a molten state as a heat transfer medium. [6]

Food additive and preservative

Sodium nitrite is used to speed up the curing of meat, [7] inhibit the germination of Clostridium botulinum spores, and also impart an attractive pink color. [8] [9] Nitrite reacts with the meat myoglobin to cause color changes, first converting to nitrosomyoglobin (bright red), then, on heating, to nitrosohemochrome (a pink pigment). [10]

Historically, salt has been used for the preservation of meat. The salt-preserved meat product was usually brownish-gray in color. When sodium nitrite is added with the salt, the meat develops a red, then pink color, which is associated with cured meats such as ham, bacon, hot dogs, and bologna. [11]

In the early 1900s, irregular curing was commonplace. This led to further research surrounding the use of sodium nitrite as an additive in food, standardizing the amount present in foods to minimize the amount needed while maximizing its food additive role. [12] Through this research, sodium nitrite has been found to give taste and color to the meat and inhibit lipid oxidation that leads to rancidity, with varying degrees of effectiveness for controlling growth of disease-causing microorganisms. [12] The ability of sodium nitrite to address the above-mentioned issues has led to production of meat with extended storage life and has improved desirable color and taste. According to scientists working for the meat industry, [13] nitrite has improved food safety. [12] This view is disputed in the light of the possible carcinogenic effects caused by adding nitrites to meat. [7]

Nitrite has the E number E250. Potassium nitrite (E249) is used in the same way. It is approved for usage in the European Union, [14] [15] USA, [16] and Australia and New Zealand. [17]

In meat processing, sodium nitrite is never used in a pure state but always mixed with common salt. This mixture is known as nitrited salt, curing salt or nitrited curing salt. In Europe, nitrited curing salt contains between 99.1% and 99.5% common salt and between 0.5% and 0.9% nitrite. In the US, nitrited curing salt is dosed at 6% and must be remixed with salt before use. [18]

Color and taste

The appearance and taste of meat is an important component of consumer acceptance. [12] Sodium nitrite is responsible for the desirable red color (or shaded pink) of meat. [12] Very little nitrite is needed to induce this change. [12] It has been reported that as little as 2 to 14 parts per million (ppm) is needed to induce this desirable color change. [19] However, to extend the lifespan of this color change, significantly higher levels are needed. [19] The mechanism responsible for this color change is the formation of nitrosylating agents by nitrite, which has the ability to transfer nitric oxide that subsequently reacts with myoglobin to produce the cured meat color. [19] The unique taste associated with cured meat is also affected by the addition of sodium nitrite. [12] However, the mechanism underlying this change in taste is still not fully understood. [19]

Inhibition of microbial pathogens

In conjunction with salt and pH levels, sodium nitrite reduces the ability of Clostridium botulinum spores to grow to the point of producing toxin. [9] [20] Some dry-cured meat products are manufactured without nitrites. For example, Parma ham, which has been produced without nitrite since 1993, was reported in 2018 to have caused no cases of botulism. This is because the interior of the muscle is sterile and the surface is exposed to oxygen. [7]

Sodium nitrite has shown varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms. [12] Although the inhibitory mechanisms are not well known, its effectiveness depends on several factors including residual nitrite level, pH, salt concentration, reductants present and iron content. [19] The type of bacteria also affects sodium nitrite's effectiveness. [19] It is generally agreed that sodium nitrite is not effective for controlling Gram-negative enteric pathogens such as Salmonella and Escherichia coli . [19]

Other food additives (such as lactate and sorbate) provide similar protection against bacteria, but do not provide the desired pink color. [21] [22]

Inhibition of lipid peroxidation

Sodium nitrite is also able to effectively delay the development of oxidative rancidity. [19] Lipid peroxidation is considered to be a major reason for the deterioration of quality of meat products (rancidity and unappetizing flavors). [19] Sodium nitrite acts as an antioxidant in a mechanism similar to the one responsible for the coloring effect. [19] Nitrite reacts with heme proteins and metal ions, neutralizing free radicals by nitric oxide (one of its byproducts). [19] Neutralization of these free radicals terminates the cycle of lipid oxidation that leads to rancidity. [19]

Medication

Sodium nitrite
Natriumnitrit.png
Chemical structure
Clinical data
AHFS/Drugs.com FDA Professional Drug Information
Pregnancy
category
ATC code
Legal status
Legal status
Identifiers
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
E number E250 (preservatives) OOjs UI icon edit-ltr-progressive.svg
CompTox Dashboard (EPA)
ECHA InfoCard 100.028.687 OOjs UI icon edit-ltr-progressive.svg
Chemical and physical data
Formula NNaO2
Molar mass 68.995 g·mol−1
3D model (JSmol)
  • N(=O)[O-].[Na+]
  • InChI=1S/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
  • Key:LPXPTNMVRIOKMN-UHFFFAOYSA-M

Sodium nitrite is used as a medication together with sodium thiosulfate to treat cyanide poisoning. [26] It is recommended only in severe cases of cyanide poisoning and has largely been replaced by use of hydroxocobalamin, [27] a form of vitamin B12, but given in much higher doses than needed nutritionally. [28] In those who have both cyanide poisoning and carbon monoxide poisoning sodium thiosulfate by itself is usually recommended if the facility does not have sufficient hydroxycobalamin [29] [30] It is given by slow injection into a vein. [26]

NaNO2 side effects are chiefly related to creation of methemoglobinemia and vasodilation. Side effects can include low blood pressure, headache, shortness of breath, loss of consciousness, and vomiting. [26] Greater care should be taken in people with underlying heart disease. [26] The patient's levels of methemoglobin should be regularly checked during treatment. [26] While not well studied during pregnancy, there is some evidence of potential harm to the baby. [31] Sodium nitrite works by creating methemoglobin, where the iron atom at the center of the heme group is in the oxidized ferric (Fe3+) state, which binds with cyanide with greater affinity than its binding to the cytochrome C oxidase, and thus removes it from blocking the metabolic function of mitochondria. [31]

Sodium nitrite came into medical use in the 1920s and 1930s. [32] [33] It is on the World Health Organization's List of Essential Medicines. [34]

Suicide

Several academic publications in 2020 and 2021 have discussed the toxicity of sodium nitrite, and an apparent recent increase in suicides using sodium nitrite which had been ordered online. [35] The usage of sodium nitrite as a suicide method has been heavily discussed on suicide forums, primarily Sanctioned Suicide. [36] Sodium nitrite was also the focal-point of the McCarthy et al. v Amazon lawsuit alleging that Amazon knowingly assisted in the deaths of healthy children by selling them "suicide kits" as Amazon's "frequently bought together" feature recommended buying sodium nitrite, an antiemetic, and a suicide instruction book together. [37] This lawsuit was dismissed in June 2023. [38] The online marketplace eBay has globally prohibited the sale of sodium nitrite since 2019. [39] Some online vendors[ who? ] of sodium nitrite have been prosecuted for assisting suicide. [40] [41] Furthermore, legislation has been introduced in the United States with the aim of deeming sodium nitrite products with a sodium nitrite concentration of greater than 10% by volume to be banned consumer products under the Consumer Product Safety Act. [42] In cases of suspected suicide involving sodium nitrite, it is critical that responding individuals administer immediate methylene blue. [43] [44] [45] Methylene blue is the antidote to the methemoglobinemia caused by intentional ingestion of sodium nitrite as a suicide agent. [46]

Toxicity

Sodium nitrite is toxic. [47] The LD50 in rats is 180 mg/kg and in humans LDLo is 71 mg/kg. [48] The mechanism by which sodium nitrite causes death is methemoglobinemia. [49] The oftentimes severe methemoglobinemia found in sodium nitrite poisoning cases results in systemic hypoxia, metabolic acidosis, and cyanosis. [50] The reported [51] signs of sodium nitrite poisoning are as follows:

"Symptoms of [nitrite] poisoning can vary depending on the amount and duration of the exposure. Those with very mild methemoglobinemia might not have any symptoms at all, or might appear a little pale and feel tired. Moderate-to-severe poisoning is associated with cyanosis (blueness of the skin), confusion, loss of consciousness, seizures, abnormal heart rhythms, and death."

With prompt action, sodium nitrite poisoning is reversible using an antidote, methylene blue. [44] It has been reported [52] that sodium nitrite poisoning can also be detected post-mortem:

"Postmortem detection of [methemoglobinemia] is typically established via screening techniques such as scene evidence suggesting fatal consumption of a toxic salt in addition to the characteristic grey-purple lividity observed upon the body. The diagnosis can be established via postmortem blood testing demonstrating elevated methemoglobin saturation. Additionally, we have confirmed that postmortem MRI in cases of [methemoglobinemia] demonstrates a T1-bright (hyperintense) signal of the blood; both within intracardiac blood on chest MRIs and postmortem blood samples in tubes."

Death by sodium nitrite ingestion can happen at lower doses than the LDLo. [53] [54] Sodium nitrite has been used for homicide [55] [56] and suicide. [57] [58] To prevent accidental intoxication, sodium nitrite (blended with salt) sold as a food additive in the US is dyed bright pink to avoid mistaking it for plain salt or sugar. In other countries, nitrited curing salt is not dyed but is strictly regulated. [59]

Occurrence in vegetables

Nitrites do not occur naturally in vegetables in significant quantities, [60] but deliberate fermentation of celery juice, for instance, with a naturally high level of nitrates, can produce nitrite levels sufficient for commercial meat curing. [61] Boiling vegetables does not affect nitrite levels. [62]

The presence of nitrite in animal tissue is a consequence of metabolism of nitric oxide, an important neurotransmitter. [63] Nitric oxide can be created de novo from nitric oxide synthase utilizing arginine or from ingested nitrite. [64]

Pigs

Due to sodium nitrite's high level of toxicity to swine (Sus scrofa) it is now being developed in Australia to control feral pigs and wild boar. [65] [66] The sodium nitrite induces methemoglobinemia in swine, i.e. it reduces the amount of oxygen that is released from hemoglobin, so the animal will feel faint and pass out, and then die in a humane manner after first being rendered unconscious. [67] The Texas Parks and Wildlife Department operates a research facility at Kerr Wildlife Management Area, where they examine feral pig feeding preferences and bait tactics to administer sodium nitrite. [68]

Cancer

Carcinogenicity is the ability or tendency of a chemical to induce tumors, increase their incidence or malignancy, or shorten the time of tumor occurrence. [69]

Adding nitrites to meat has been shown to generate known carcinogens such as nitrosamines; the World Health Organization (WHO) advises that 50 g (1.8 oz) of "processed meats" a day would raise the risk of getting bowel cancer by 18% over a lifetime, and eating larger amounts raises the risk more. The World Health Organization's review of more than 400 studies concluded, in 2015, that there was sufficient evidence that "processed meats" caused cancer, particularly colon cancer; [7] the WHO's International Agency for Research on Cancer (IARC) classified "processed meats" as carcinogenic to humans (Group 1); "processed meat" meaning meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation.). [7] [70]

Nitrosamines can be formed during the curing process used to preserve meats, when sodium nitrite-treated meat is cooked, and also from the reaction of nitrite with secondary amines under acidic conditions (such as occurs in the human stomach). Dietary sources of nitrosamines include US cured meats preserved with sodium nitrite as well as the dried salted fish eaten in Japan. In the 1920s, a significant change in US meat curing practices resulted in a 69% decrease in average nitrite content. This event preceded the beginning of a dramatic decline in gastric cancer mortality. [71] Around 1970, it was found that ascorbic acid (vitamin C), an antioxidant, inhibits nitrosamine formation. [72] Consequently, the addition of at least 550 ppm of ascorbic acid is required in meats manufactured in the United States. Manufacturers sometimes instead use erythorbic acid, a cheaper but equally effective isomer of ascorbic acid. Additionally, manufacturers may include α-tocopherol (vitamin E) to further inhibit nitrosamine production. α-Tocopherol, ascorbic acid, and erythorbic acid all inhibit nitrosamine production by their oxidation-reduction properties. Ascorbic acid, for example, forms dehydroascorbic acid when oxidized, which when in the presence of nitrosonium, a potent nitrosating agent formed from sodium nitrite, reduces the nitrosonium into nitric oxide. [73] The nitrosonium ion formed in acidic nitrite solutions is commonly [74] [75] mislabeled nitrous anhydride, an unstable nitrogen oxide that cannot exist in vitro. [76]

Ingesting nitrite under conditions that result in endogenous nitrosation has been classified as "probably carcinogenic to humans" by International Agency for Research on Cancer (IARC). [77] [78]

Sodium nitrite consumption has also been linked to the triggering of migraines in individuals who already experience them. [79]

One study has found a correlation between highly frequent ingestion of meats cured with pink salt and the COPD form of lung disease. [80] [81] The study's researchers suggest that the high amount of nitrites in the meats was responsible; however, the team did not prove the nitrite theory. Additionally, the study does not prove that nitrites or cured meat caused higher rates of COPD, merely a link. The researchers did adjust for many of COPD's risk factors, but they commented they cannot rule out all possible unmeasurable causes or risks for COPD. [82] [83]

Production

Industrial production of sodium nitrite follows one of two processes, the reduction of nitrate salts, or the oxidation of lower nitrogen oxides.

One method uses molten sodium nitrate as the salt, and lead which is oxidized, while a more modern method uses scrap iron filings to reduce the nitrate. [4] [84]

NaNO3 + Pb → NaNO2 + PbO

A more commonly used method involves the general reaction of nitrogen oxides in alkaline aqueous solution, with the addition of a catalyst. The exact conditions depend on which nitrogen oxides are used, and what the oxidant is, as the conditions need to be carefully controlled to avoid over oxidation of the nitrogen atom. [4]

2 NaOH + NO2 + NO → 2 NaNO2 + H2O
2 NaOH + N2O3 → 2 NaNO2 + H2O

Sodium nitrite has also been produced by reduction of nitrate salts by exposure to heat, light, ionizing radiation, metals, hydrogen, and electrolytic reduction. [85]

NaNO3 + CaSO3 → NaNO2 + CaSO4

Chemical reactions

In the laboratory, sodium nitrite can be used to destroy excess sodium azide. [86] [87]

2 NaN3 + 2 NaNO2 + 4 H+ → 3 N2 + 2 NO + 4 Na+ + 2 H2O

Above 330 °C sodium nitrite decomposes (in air) to sodium oxide, nitric oxide and nitrogen dioxide. [88]

2 NaNO2 → Na2O + NO + NO2

Sodium nitrite can also be used in the production of nitrous acid:

2 NaNO2 + H2SO4 → 2 HNO2 + Na2SO4

The nitrous acid then, under normal conditions, decomposes:

2 HNO2 → NO2 + NO + H2O

The resulting nitrogen dioxide hydrolyzes to a mixture of nitric and nitrous acids:

2 NO2 + H2O → HNO3 + HNO2

Isotope labelling 15N

15N isotope enriched NaNO2 15n isotope.jpg
15N isotope enriched NaNO2

In organic synthesis isotope enriched sodium nitrite-15N can be used instead of normal sodium nitrite as their reactivity is nearly identical in most reactions.

The obtained products carry isotope 15N and hence nitrogen NMR can be efficiently carried out. [89]

Related Research Articles

<span class="mw-page-title-main">Amyl nitrite</span> Chemical compound

Amyl nitrite is a chemical compound with the formula C5H11ONO. A variety of isomers are known, but they all feature an amyl group attached to the nitrite functional group. The alkyl group (the amyl in this case) is unreactive and the chemical and biological properties are mainly due to the nitrite group. Like other alkyl nitrites, amyl nitrite is bioactive in mammals, being a vasodilator, which is the basis of its use as a prescription medicine. As an inhalant, it also has a psychoactive effect, which has led to its recreational use, with its smell being described as that of old socks or dirty feet. It was first documented in 1844 and came into medical use in 1867.

<span class="mw-page-title-main">Nitrate</span> Polyatomic ion (NO₃, charge –1) found in explosives and fertilisers

Nitrate is a polyatomic ion with the chemical formula NO
3
. Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble nitrate is bismuth oxynitrate.

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 undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined.

<span class="mw-page-title-main">Potassium nitrate</span> Chemical compound

Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula KNO3. It is a potassium salt of nitric acid. This salt consists of potassium cations K+ and nitrate anions NO−3, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter. It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpetre.

<span class="mw-page-title-main">Sodium nitrate</span> Chemical compound

Sodium nitrate is the chemical compound with the formula NaNO
3
. This alkali metal nitrate salt is also known as Chile saltpeter to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.

<span class="mw-page-title-main">Nitric oxide</span> Colorless gas with the formula NO

Nitric oxide is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula. Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding.

<span class="mw-page-title-main">Nitrous acid</span> Chemical compound

Nitrous acid is a weak and monoprotic acid known only in solution, in the gas phase, and in the form of nitrite salts. It was discovered by Carl Wilhelm Scheele, who called it "phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.

The nitrite ion has the chemical formula NO
2
. Nitrite is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.

<span class="mw-page-title-main">Nitrosamine</span> Organic compounds of the form >N–N=O

In organic chemistry, nitrosamines are organic compounds with the chemical structure R2N−N=O, where R is usually an alkyl group. They feature a nitroso group bonded to a deprotonated amine. Most nitrosamines are carcinogenic in nonhuman animals. A 2006 systematic review supports a "positive association between nitrite and nitrosamine intake and gastric cancer, between meat and processed meat intake and gastric cancer and oesophageal cancer, and between preserved fish, vegetable and smoked food intake and gastric cancer, but is not conclusive".

<span class="mw-page-title-main">Processed meat</span> Type of meat

Processed meat is considered to be any meat that has been modified in order to either improve its taste or to extend its shelf life. Methods of meat processing include salting, curing, fermentation, smoking, and/or the addition of chemical preservatives. Processed meat is usually composed of pork or beef or, less frequently, poultry. It can also contain offal or meat by-products such as blood. Processed meat products include bacon, ham, sausages, salami, corned beef, jerky, hot dogs, lunch meat, canned meat, chicken nuggets, and meat-based sauces. Meat processing includes all the processes that change fresh meat with the exception of simple mechanical processes such as cutting, grinding or mixing.

<span class="mw-page-title-main">Nitrosation and nitrosylation</span> Process of converting organic compounds into nitroso derivatives

Nitrosation and nitrosylation are two names for the process of converting organic compounds or metal complexes into nitroso derivatives, i.e., compounds containing the R−NO functionality. The synonymy arises because the R-NO functionality can be interpreted two different ways, depending on the physico-chemical environment:

<span class="mw-page-title-main">Charcuterie</span> Branch of cooking of prepared meat products, primarily from pork

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<span class="mw-page-title-main">Nitroso</span> Class of functional groups with a –N=O group attached

In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.

The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.

<span class="mw-page-title-main">Curing salt</span> Salt used in food preservation

Curing salt is used in meat processing to generate a pinkish shade and to extend shelf life. It is both a color agent and a means to facilitate food preservation as it prevents or slows spoilage by bacteria or fungus. Curing salts are generally a mixture of sodium chloride and sodium nitrite, and are used for pickling meats as part of the process to make sausage or cured meat such as ham, bacon, pastrami, corned beef, etc. Though it has been suggested that the reason for using nitrite-containing curing salt is to prevent botulism, a 2018 study by the British Meat Producers Association determined that legally permitted levels of nitrite have no effect on the growth of the Clostridium botulinum bacteria that causes botulism, in line with the UK's Advisory Committee on the Microbiological Safety of Food opinion that nitrites are not required to prevent C. botulinum growth and extend shelf life..

<span class="mw-page-title-main">Curing (food preservation)</span> Food preservation and flavouring processes based on drawing moisture out of the food by osmosis

Curing is any of various food preservation and flavoring processes of foods such as meat, fish and vegetables, by the addition of salt, with the aim of drawing moisture out of the food by the process of osmosis. Because curing increases the solute concentration in the food and hence decreases its water potential, the food becomes inhospitable for the microbe growth that causes food spoilage. Curing can be traced back to antiquity, and was the primary method of preserving meat and fish until the late 19th century. Dehydration was the earliest form of food curing. Many curing processes also involve smoking, spicing, cooking, or the addition of combinations of sugar, nitrate, and nitrite.

<span class="mw-page-title-main">Cured fish</span> Fish subjected to fermentation, pickling or smoking

Cured fish is fish which has been cured by subjecting it to fermentation, pickling, smoking, or some combination of these before it is eaten. These food preservation processes can include adding salt, nitrates, nitrite or sugar, can involve smoking and flavoring the fish, and may include cooking it. The earliest form of curing fish was dehydration. Other methods, such as smoking fish or salt-curing also go back for thousands of years. The term "cure" is derived from the Latin curare, meaning to take care of. It was first recorded in reference to fish in 1743.

<span class="mw-page-title-main">Transition metal nitrite complex</span> Chemical complexes containing one or more –NO₂ ligands

In organometallic chemistry, transition metal complexes of nitrite describes families of coordination complexes containing one or more nitrite ligands. Although the synthetic derivatives are only of scholarly interest, metal-nitrite complexes occur in several enzymes that participate in the nitrogen cycle.

In biochemistry, nitrosamines are a class of compounds that can form during food digestion. The presence of their precursors, nitrites, in cured meats, is controversial, because of a small connection to cancer risk.

<i>N</i>-Nitrosomorpholine Chemical compound

N-Nitrosomorpholine is an organic compound which is known to be a carcinogen and mutagen.

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