E250, Nitrous Acid, Sodium Salt
Nitrous acid, sodium salt    
CAS #: 7632-00-0    

CAS Number: 7632-00-0 
EC Number: 231-555-9
E number: E250 (preservatives)

Sodium nitrite is the inorganic compound, the nitrate salt of nitrous acid with the chemical formula NaNO2.

Sodium nitrite is an inorganic compound with the chemical formula NaNO2. 
Sodium nitrite is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. 
From an industrial perspective, Sodium nitrite is the most important nitrite salt. 
Sodium nitrite 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.

Sodium nitrite represented by the chemical formula NaNO2 is a nitrous acid sodium salt that is soluble in water and aqueous acid. 

Sodium Nitrite is common metal corrosion inhibitor for iron & steel and is typically used in closed-loop cooling water treatment products, such as chiller systems. 

Sodium nitrite is used for the production of diazo compounds and as a component of hydronic salts. 
Furthermore, sodium nitrite is an important basic material for the dyeing of textiles and is used in the chemical, pharmaceutical, and metal industry. 

Sodium nitrite is a solid chemical substance which is found in nature in the form of a white or yellow powder, and is naturally hygroscopic - that is it attracts water from the environment. 
This substance is utilized in various industries ranging from pharmaceutical to food processing to industrial machinations. 
Another prominent application of this substance lies in the dye industry, where it is used for the production of diazo dyes, utilized subsequently in the textile industry. 

Sodium nitrite is used in many industrial processes, in meat curing, coloring, and preserving, and as a reagent in analytical chemistry. 

Sodium nitrite is used as a coloring agent or preservative in food, as well as an antimicrobial agent in meat and fish and some cheeses.

Sodium Nitrite, chemical formula NaNO2, is a pale straw-colored material that is highly soluble in water. 
Sodium Nitrite is used in many industrial applications including the manufacturing of diazo dyes, and other organic compounds used in the manufacture of organic pigments for the paint, dye and printing ink industries. 
In metal processing, Sodium nitrite is used in phosphatizing and detinning applications. 
As a molten salt bath, Sodium nitrite is used in heat treating of metal parts in the automotive and aircraft industries and as a high temperature heat-transfer medium. 
Sodium nitrite is also used in the manufacture of synthetic rubbers and rubber chemicals. 
Due to its anti-corrosion properties, Sodium Nitrite solution is also used as a heat transfer fluid in Thermal Energy Storage units for large air-conditioning or process cooling applications.

CAS names
Nitrous acid, sodium salt (1:1)
IUPAC names
2,4-dichlorophénoxyacétate de dimethylammonium
Nitrous acid, sodium salt (1:1)

Trade names
Nitrous acid sodium salt (1:1)
Nitrous acid, sodium salt (8CI, 9CI)
Sodium nitrite

Sodium nitrite is non-combustible itself but assists the burning of combustible material. 
Sodium nitrite is an ionic compound and a strong reducing agent. 
In acidic solution, though, Sodium nitrite mainly executes oxidation reactions.

Sodium nitrite is a color fixative; Sodium nitrite is used in dyeing and printing textile fabrics and bleaching fibers. 
When it's pure Sodium nitrite is a white to slightly yellow crystaline powder. 
It's very soluable in water and hydroscopic. 
Also, Sodium nitrite is a strong reducing agent. 
Sodium nitrite preserves fish and meat, and prevents the growth of bacteria. 
Another thing Sodium nitrite does is it increases blood flow by dialating blood vessels. 
Sodium nitrite's used in laxative, vasodilater, bronchodilator, and an antidote for cyanide poinsioning.

Sodium nitrite prevents the growth of a harmful bacterium called Clostridium botulinum and it may also have preservation effects on other harmful and spoilage bacteria. 
In addition, nitrite develops cured meat flavour and colour and retards the development of rancidity and off-odours and off-flavours during storage of cured meats. 
Sodium nitrite is responsible for the characteristic pink colour of cured meats.

Sodium nitrite as a corrosion inhibitor is widely used for protecting equipment components made of carbon steel. 
Sodium nitrite is well known that nitrite addition at several grams per liter level can efficiently reduce carbon steel corrosion even in sea water.

Sodium nitrite is used as an accelerator in some zinc phosphate solutions.

231-555-9 [EINECS]
7632-00-0 [RN]
Azotyn sodowy [Polish]
Dusitan sodny [Czech]
MFCD00011118 [MDL number]
NaNO2 [Formula]
Natrium nitrit [German]
Natriumnitrit [German] [ACD/IUPAC Name]
Nitrite de sodium [French] [ACD/IUPAC Name]
Nitrito sodico [Spanish]
Nitrous acid sodium salt
Sodium nitrate(III)
Sodium nitrite [ACD/IUPAC Name] [Wiki]
Sodium nitrite [UN1500] [Oxidizer]
32863-15-3 [RN]
56227-20-4 [RN]
68378-96-1 [RN]
82497-43-6 [RN]
82998-40-1 [RN]
Azotyn sodowy
Azotyn sodowy [Polish]
diazoting salts
Dusitan sodny
Dusitan sodny [Czech]
EINECS 231-555-9
Natrium nitrit
Natrium nitrit [German]
Nitrite de sodium [ACD/IUPAC Name]
Nitrite de sodium [French]
Nitrite sodium
Nitrite, Sodium
Nitrito sodico
Nitrito sodico [Spanish]
Nitrous Acid Soda
Nitrous acid, sodium salt
Sodium nitrite (NaNO2 )
Sodium nitrite (USP)
Sodium nitrite ACS grade
Sodium nitrite, Trace metals grade
亚硝酸钠 [Chinese]

Nitrous acid, sodium salt
Natrium nitrit
Nitrito sodico
Sodium nitrite solution
Nitrite de sodium

Sodium nitrite [USP]
Nitrous acid, sodium salt (1:1)
Sodium nitrite (USP)
Nitrite, sodium
Caswell No. 782
Dusitan sodny [Czech]
Azotyn sodowy [Polish]
Azotyn sodowy

IUPAC name: Sodium nitrite
Other names: Nitrous acid, sodium salt

Chemical formula: NaNO2
Molar mass: 68.9953 g/mol
Appearance: White or slight yellowish solid
Odor: Odorless
Density: 2.168 g/cm3
Melting point    : 271 °C (520 °F; 544 K)
Boiling point: 320 °C (608 °F; 593 K) (decomposes)
Solubility in water
71.4 g/100 mL (0 °C)
84.8 g/100 mL (25 °C)
160 g/100 mL (100 °C)

Solubility: Very soluble in anhydrous ammonia
Soluble in ethanol
Solubility in ethanol:3 g/100 ml
Solubility in methanol: 4.4 g/100 ml
Solubility in diethyl ether: 0.3 g/100 mL

Acidity (pKa): ~9

Std molar entropy (So298) : 106 J·mol-1·K-1
Std enthalpy of formation (ΔfHo298) : −359 kJ/mol

Safety data sheet    
Lethal dose or concentration (LD, LC):
LD50 (Median dose): 180 mg/kg (rats, oral)

Sodium Nitrite Uses
In meat curing, preservation and coloring.
As a reagent in techniques involving analytical chemistry.
As a corrosion inhibitor, food additive, hog poison and an antidote to cyanide poisoning (used in combination with sodium thiosulfate).
For the production of various dyes and fertilizers.
For bleaching fibers and printing textile fabrics.
As a laxative, bronchodilator and vasodilator in the medical field 

Sodium nitrite appears as a yellowish white crystalline solid. 
Sodium nitrite is noncombustible but will accelerate the burning of combustible material. 
If large quantities are involved in a fire or if the combustible material is finely divided, an explosion may result. 
If contaminated by ammonium compounds, spontaneous decomposition can occur and the resulting heat may ignite surrounding combustible material. 
Prolonged exposure of Sodium nitrite heat may result in an explosion. 
Toxic oxides of nitrogen are produced in fires involving this material. 
Sodium nitrite  is used as a food preservative, and to make other chemicals.

CAMEO Chemicals
Sodium nitrite is an inorganic sodium salt having nitrite as the counterion. Used as a food preservative and antidote to cyanide poisoning. It has a role as an antimicrobial food preservative, an antihypertensive agent, a food antioxidant, a poison and an antidote to cyanide poisoning. It is a nitrite salt and an inorganic sodium salt.

Sodium nitrite solution appears as a clear colorless to yellow solution. Harmful to the environment and somewhat toxic. Used as a preservative, and to make other chemicals.

Sodium nitrite (NaNO2) is a preserving agent. 
Sodium nitrite is used in bacon, baloney, corned beef, hams, hot dog wieners, luncheon meats, salami and sausages as well as smoked and cured fishes.
Sodium nitrite helps prevent food from going rancid, and controls bacteria

Sodium nitrite also helps hold colour in preserved meats or fish. 
Some of the nitrites in it convert to nitric oxide, which interacts with myoglobin in meat, forming red nitric oxide myoglobin. 
This turns bright pink when the meat is smoked, giving preserved meat a pleasing pink colour.

Sodium nitrite is a white or white-yellowish hygroscopic solid, soluble in water and slightly soluble in primary alcohols, while insoluble in alkanes and chlorocarbons. It has a density of 2.168 g/cm3. It melts when heated to 271 °C, and will also decompose, with significant decomposition starting above 320 °C.

Sodium nitrite can be found as food additive. It is usually dyed pink to differentiate it from table salt. The dye can be removed by washing it with a solvent and further purification can be achieved by recrystallizing the sodium nitrite.

Sodium Nitrite Food Grade

Using Sodium Nitrite, it is easier to make the exact concentration for preserving meat and sausage products with pickle-salt

Sodium Nitrite free flowing food grade with anti-caking agent (SiO2)
Sodium Nitrite food grade (E 250) without anti-caking agent

Sodium nitrite is a special kind of salt that is used in making cured meat and poultry products. 
Curing is a flavouring process that gives meats like bacon, ham and hot dogs their characteristic colour and flavour. 
Butterball Bacon Style Turkey, Butterball Franks, Butterball Turkey Bacon-Rasher, and a small number of similar products are formulated with sodium nitrite for this effect.

Sodium nitrite also has a food preservation effect. It blocks the growth of dangerous bacteria that can cause illness. 
It extends shelf life and storage stability of highly perishable foods including meat, fish and vegetables.

Sodium nitrite Chemical Properties,Uses and Production

Physicochemical property
Chemical formula is NaNO2, in which N has a valency is + III.
It is colorless or yellow crystal, the relative density is 2.168 (0℃), the melting point is 271℃, and it is decomposed when 320℃. 
It is soluble in water, and aqueous solution is alkaline because of nitrate hydrolysis. Sodium nitrite has the characteristics of reduction and oxidation and is mainly oxidation. In acidic solution, the main performance is oxidation. In alkaline solution or in case of strong oxidizing agent, its performance is reduction. With sulfur, phosphorus, organic matter and other friction or impact can cause combustion or explosion. Sodium nitrite can be placed in the air with the oxygen reaction, and gradually produce sodium nitrate: NaNO2+1/2O2=NaNO3.
When using strong acidic sodium nitrite, it can be nitrited to nitric acid. Nitrite is very unstable, easily decomposed into nitrogen dioxide, nitric oxide and water. 
The nitrogen atoms and oxygen atoms all have a single pair of electrons, which can be used as ligands, and can be used as ligands to form complexes with many metal ions. 
Sodium nitrite is toxic, carcinogenic substances, using it must be attention. It is used in printing and dyeing industry and organic synthesis. 
Sodium nitrite is obtained by the reaction of sodium nitrate and lead in a total of hot condtion.
The reaction mixture obtained by hot water treatment, filtration to remove insoluble lead oxide, concentration and crystallization of sodium nitrite crystal can be obtained.
white sodium nitrite crystal powder
Figure 1 white sodium nitrite crystal powder
The information of this information is compiled by ChemicalBook Xiao Nan

Sodium nitrite is also a kind of antidote, can make the oxidation of hemoglobin to methemoglobin, and is easy to combine with cyanide ions and produce non-toxic cyanide methemoglobin, then after given sodium thiosulfate, it change into non-toxic sulphur cyanogen compounds, and excreted. The detoxification process is similar to methylene blue. And the effect is stronger than the methylene blue. It keeps for a long time. It is used to save cyanide poisoning.
[Mechanism] Cyanide and ferric iron (Fe3 +) of mitochondrial cytochrome oxidasewith have high affinity, after making enzyme lost activity, inhibiting cell respiration and causing cells to lactic acidosis and lack of oxygen.This oxidizing agent can make the ferrous iron in hemoglobin (Fe2 +) oxidized to ferric iron (Fe3 +), forming methemoglobin. Iron Fe3+ of methemoglobin MHb and cyanide (CN) combine stronger than Fe3 + of cytochrome oxidaseis. Even if CN-has combined with cytochrome oxidase can also make release again, and recovery of enzyme activity. But after methemoglobin combined with CN-, the formation of the cyanide methemoglobin gradually disintegrate within a few minutes, later release the CN-, and toxicity of cyanide recover. So this product only for cyanide poisoning has a temporary delay its toxicity.This product is to dilate blood vessels.
Severe adverse reactions in injection , should immediately stop drug.
In the treatment of cyanide poisoning, the product with sodium thiosulfate can cause blood pressure to drop, blood pressure change should be paid attention to.
Injection of large dose of this product cause methemoglobin present violet purple, available methylene blue make methemoglobin reduction.
This product on cyanide poisoning are only temporary delay its toxicity. 
So after the application of this product, immediately injection of sodium thiosulfate by the original intravenous needle, make it combine with chlorine, and become less toxic thiocyanate by urine.
It must be in the poisoning, early application of poisoning time longer, no detoxification.
The use of drug , the amount is not too small,.It should be developed livestock slightly blue, can quickly and effectively detoxified.
The dosage is too large, it can be due to formation excessive methemoglobin, presenting purple, breathing difficulties and other hypoxia symptoms.
The water solubility (g / 100 ml)
At different temperature (℃),It dissolve grams per 100 ml of water:
71.2 g/0 ℃;75.1 g/10 ℃;80.8 g/20 ℃;87.6 g/30 ℃.94.9 g/40 ℃;111 g/60 ℃;113 g/80 ℃;160 g/100 ℃

LD50 orally in rats: 180 mg/kg (Smyth)

Limited use
GB 2760-1996 (g/kg): pickled meat of livestock and poultry, canned meat, pickled salted ham 0.15; residue 0.07.

Chemical property
It is white or yellow patch on the orthorhombic crystal or powder. Micro salty and deliquescent. It is soluble in water and liquid ammonia, its aqueous solution is alkaline.

As send lubricious agent, Sodium nitrite is used in meat products processing.
Sodium nitrite is used as a common analytical reagent, oxidant and diazotization reagent, also used for the synthesis of nitrite and nitroso compound .
Used as a mordant, bleach, metal heat treatment, electroplating, corrosion inhibitor, medicine, used as instrument disinfectant and preservative, etc.
Used as the production for ice dye, sulphur dyes, direct dyes, acid dyes, disperse dyes, basic dyes, hair dye, H hole aid. 
Also it is used in the production of amino azobenzene, para amino phenol intermediates, etc. 
Also it is used in production of organic pigments, such as silver bead R, bright red, big red, bright red candle, toluidine mauve, scarlet lake, lithol scarlet, fast bordeaux lake CK, etc. It is used in the manufacture of ethylamine pyrimidine, aminopyrin and so on in the pharmaceutical industry. 
It is used in the production of vanillin, and used as bleaching for silk and flax and mordant dyeing of fabrics. 
Also it is used for metal heat treatment and plating corrosion inhibitor. 
It is used for cutting oil, lubricating oil, antifreeze liquid and hydraulic system.
Sodium nitrite is allowed to use the hair color agent in China. 
It is excluded nitrite under the action of lactic acid in the meat, and then decompose the nitroso (N0), the latter with myoglobin can generate nitroso myoglobin of the bright red color, and can produce a special flavor. Sodium nitrite can inhibit a variety of anaerobic clostridium spore bacteria, especially for clostridium botulinum. 
Regulations in China can be used for canning class livestock and poultry meat and meat products, the maximum amount is 0.15 g/kg, Residues (according to sodium nitrite) shall not be more than 0.03 g/kg in meat products, residues of 0.07 g/kg in pickle brine ham. It can also be used in canned meat, shall not be more than 0.05 g/kg.
It is used as a hair color agent in meat products processing, and can be used in canned meat and meat products. 
It has a certain role on inhibit microbial proliferation in the meat products(with special inhibition on clostridium botulinum), and can improve the flavor of bacon as a preservative.
It is used as meat send lubricious agent, Antimicrobial agent, and Preservatives.
In Japan, It can be used in canned meat, ham, sausage, bacon, corned beef and other meat products. 
It can be used as ascorbic acid, ascorbic acid, cysteine and nicotinamide as color auxiliary. The Dosage is reference.

Methods of production
Ammonia is oxidated to nitrous oxide gas, which is with sodium hydroxide or sodium carbonate solution absorption.
The procession of Pb reduction the sodium nitrate The sodium nitrate is heated to melt, adding a small amount of metallic lead, continue to stir and heated to all oxidation of lead. 
The generated block cooling and divided into small pieces, and several times with hot water extraction generated to lead oxide. 
Bubbled into carbon dioxide generated lead carbonate precipitation, filtered, with dilute nitric acid and filtrate correctly, the evaporation and crystallization precipitation of concentrated sodium nitrite. 
After suction, it obtained by dry after washing with ethanol and recrystallization refined again.

2. The method of absorption: The containing tail gas is removed from absorption access to the bottom in the dilute nitric acid production process, the consumption of sodium carbonate solution of 20%~30% down from the tower spray to absorb nox in the exhaust gas, generated neutralization solution. 
When relative density of the solution is 1.24~1.25, the content of sodium carbonate is 3~5 g/L, the agent of arsenic and heavy metal removal agent purification, filtration to remove impurities such as arsenic and heavy metals, the refined solution by evaporating, cooling crystallization, centrifugal separation, drying, consumption of sodium nitrite was finished.
Na2CO3 + NO + N02→2NaNO2 + CO2
Na2CO3 + 2N02→NaNO2 + NaNO3 + CO2
The centrifugal separation of the mother liquor, it is used as the material of producing edible sodium nitrate.

3. With caustic soda or soda ash solution absorbing tail gas containing a small amount of NO and NO2 in nitric acid or a nitrate production. 
In the tail gas of NO/NO2 ratio to adjust to the NaNO2 and NaNO3 in the neutralization liquid ratio below 8. 
The quality of the liquid in the process of absorption and should avoid acid, so as to avoid corrosion of the equipment. 
When the relative density of liquid is 1.24~1.25, the content of soda ash is 3~5 g/L and send to evaporation, absorb liquid evaporation concentration at 132 ℃, then cool to 75 ℃, precipitation sodium nitrite in crystallization, then through separation, drying to quick product.
Na2CO3 + NO + NO2→2 NaNO2 + CO2

oxidizing agent
Toxicity grading
high toxic
Acute toxicity
Orally administered: rats LD50:85 mg/kg , mice LD50: 175 mg/kg
Stimulus data
Eyes-Rabbit 500 mg mild
Explosive hazard characteristics
Mixed with reducing agent, heat, impact, friction can be explosive
Combustible hazard
The heat decomposition can produce toxic nitrogen oxide and sodium oxide smoke
Storage and transportation characteristics
Warehouse ventilation and low temperature drying; separate storage with organic matter, reducing agent, and other flammable materials, food raw materials.
fire extinguishing agent
Water spray, sandy soil
Professional standards
TWA 1mg/m3 , STET 3mg/m3
Chemical Properties
Sodium nitrite, NaN02, is a fire-hazardous, air-sensitive, yellowish white powder that is soluble in water and decomposes at temperatures above 320°C (608 °F). Sodium nitrite is used as an intermediate for dye stuffs and for pickling of meat, in dyeing of textiles, in rustproofing, in medicine, and as a reagent in organic chemistry.

Sodium nitrite is a myeloperoxidase inhibitor with IC50 of 1.3 μM

manufacture of diazo dyes, nitroso Compounds, and in many other processes of manufacture of organic chemicals; dyeing and printing textile fabrics; bleaching flax, silk, and linen; photography. In meat curing, coloring and preserving; in processing smoked chub. Also as reagent In animal chemistry.

Sodium Nitrite is the salt of nitrous acid that functions as an anti- microbial agent and preservative. 
Sodium Nitrite is a slightly yellow granular powder or nearly white, opaque mass or sticks. Sodium Nitrite is deliquescent in air. 
Sodium Nitrite has a solubility of 1 g in 1.5 ml of water. Sodium Nitrite is used in meat curing for color fixation and development of flavor. see nitrite.

sodium nitrite: A yellow hygroscopic crystalline compound, NaNO2,soluble in water, slightly soluble inether and in ethanol; rhombohedral;r.d. 2.17; m.p. 271°C; decomposesabove 320°C. 
It is formed by the thermal decomposition of sodium nitrate and is used in the preparation of nitrous acid (reaction with cold dilute hydrochloric acid). 
Sodium nitrite is used in organic diazotization and as a corrosion inhibitor.

Production Methods
Sodium nitrite, yellowish-white solid, soluble, formed (1) by reaction of nitric oxide plus nitrogen dioxide and sodium carbonate or hydroxide, and then evaporating, (2) by heating sodium nitrate and lead to a high temperature, and then extracting the soluble portion (lead monoxide insoluble) with H2O and evaporating. Used as an important reagent (diazotizing) in organic chemistry.

ChEBI: An inorganic sodium salt having nitrite as the counterion. Used as a food preservative and antidote to cyanide poisoning.

General Description
A yellowish white crystalline solid. Noncombustible but will accelerate the burning of combustible material. 
If large quantities are involved in a fire or if the combustible material is finely divided, an explosion may result. If contaminated by ammonium compounds, spontaneous decomposition can occur and the resulting heat may ignite surrounding combustible material. Prolonged exposure heat may result in an explosion. Toxic oxides of nitrogen are produced in fires involving Sodium nitrite. Used as a food preservative, and to make other chemicals.

Air & Water Reactions
Soluble in water.

Reactivity Profile
Sodium nitrite is an oxidizing agent. Mixtures with phosphorus, tin(II) chloride or other reducing agents may react explosively [Bretherick 1979 p. 108-109]. If contaminated by ammonium compounds, spontaneous decomposition can occur and resulting heat may ignite surrounding combustible material. Reacts with acids to form toxic nitrogen dioxide gas. Mixing with liquid ammonia forms dipotassium nitrite, which is very reactive and easily explosive [Mellor 2, Supp. 3:1566 1963]. Melting together wilh an ammonium salt leads to a violent explosion [Von Schwartz 1918 p. 299]. A mixture with potassium cyanide may cause an explosion. Noncombustible but accelerates the burning of all combustible material. If large quantities are involved in fire or if the combustible material is finely divided, an explosion may result. When a little ammonium sulfate is added to fused potassium nitrite, a vigorous reaction occurs attended by flame [Mellor 2:702. 1946-47].

Dangerous fire and explosion risk when heated to 537C (1000F) or in contact with reducing materials; a strong oxidizing agent. Carcinogen in test animals; its use in curing fish and meat products is restricted to 100 ppm.

Health Hazard
Ingestion (or inhalation of excessive amounts of dust) causes rapid drop in blood pressure, persistent and throbbing headache, vertigo, palpitations, and visual disturbances; skin becomes flushed and sweaty, later cold and cyanotic; other symptoms include nausea, vomiting, diarrhea (sometimes), fainting, methemoglobinemia. Contact with eyes causes irritation.

Safety Profile
Human poison by ingestion. Experimental poison by ingestion, inhalation, subcutaneous, intravenous, and intraperitoneal routes. Human systemic effects by ingestion: motor activity changes, coma, decreased blood pressure with possible pulse rate increase without fall in blood pressure, arteriolar or venous dlation, nausea or vomiting, and blood me themoglo binemiacarboxyhemoglobinemia. Experimental teratogenic and reproductive effects. An eye irritant. Questionable carcinogen with experimental neoplas tigenic and tumorigenic data. Human mutation data reported. It may react with organic amines in the body to form carcinogenic nitrosamines. Flammable; a strong oxidizing agent. In contact with organic matter, will ignite by friction. May explode when heated to over 100O0F or on contact with cyanides, NH4' salts, cellulose, LI, (K + NH3), Na2S203. Incompatible with aminoguanidine salts, butadene, phthalic acid, phthalic anhydride, reductants, sodlum amide, sodmm disulfite, sodium thocyanate, urea wood. When heated to decomposition it emits toxic fumes of NOx and NaaO. See also NITRITES.

Purification Methods
Crystallise NaNO2 from hot water (0.7mL/g) by cooling to 0o, or from its own melt. Dry it over P2O5. (See KNO2.)
Sodium nitrite Preparation Products And Raw materials

Raw materials
Ammonium hydroxide 4-Chlorobenzaldehyde Lead monoxide NITROUS ACID Nitrogen Tetroxide NITRIC OXIDE CARBON DIOXIDE METALI LEAD Nitric acid Sodium hydroxide Sodium nitrate Sodium carbonate

Preparation Products
2-Fluoro-6-methylpyridine Pigment Yellow 14 Pigment Red 146 5-[4-FLUORO-3-(TRIFLUOROMETHYL)PHENYL]-2-FURALDEHYDE 6-Hydroxyindazole N,N-DIETHYL-P-PHENYLENEDIAMINE MONOHYDROCHLORIDE 2-Fluorobenzotrifluoride DIRECT FAST BLACK G Chelidamic acid 6-Fluoronicotinic acid 4-Hydroxy-2,6-dimethylpyridine 2-Bromo-5-nitrothiazole ETHYL 2-CHLORO-4-METHYL-1,3-THIAZOLE-5-CARBOXYLATE 9-DIETHYLAMINO-2-HYDROXY-5H-BENZ(A)- 2-Fluoro-5-methylpyridine Reactive Red 15 3-BROMO-6-NITROINDAZOLE 4-(N,N-Diethyl)-2-methyl-p-phenylenediamine monohydrochloride 1H-INDAZOLE-3-CARBONITRILE 4-(N-Ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine sulfate Sodium benzotriazole 4-Fluorobenzotrifluoride 8-AZAXANTHIN 7-Nitroindazole 5-AMINOINDAZOLE 3-Fluorobenzotrifluoride 4-Iodopyridine 2-HYDROXY-4-PYRIDINECARBOXALDEHYDE 5-[4-(TRIFLUOROMETHOXY)PHENYL]-2-FURALDEHYDE NITROMALONALDEHYDE SODIUM 3-CHLORO-5-NITRO-1H-INDAZOLE 6-Nitroindazole 2 BASIC ORANGE 2 Mordant Black 9 1,3-DIMETHOXY-5-FLUOROBENZENE 1H-INDAZOLE-3-CARBOXYLIC ACID ETHYL ESTER (S)-(+)-2-HYDROXY-3-METHYLBUTYRIC ACID 5-(4-Bromophenyl)furfural DL-ALPHA-HYDROXYCAPROIC ACID, 95 1-Methyl-4-Ethoxycarbonyl Pyrazole-5-Sulfonamide

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.[3]

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

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

Main article: Sodium nitrite (medical use)
Sodium nitrite is an efficient drug in case of cyanide poisoning. 
It is used together with sodium thiosulfate.
It is on the World Health Organization's List of Essential Medicines.

Food additive and preservative
Sodium nitrite is used to speed up the curing of meat and also impart an attractive pink color.
Nitrite reacts with the meat myoglobin to cause color changes, first converting to nitrosomyoglobin (bright red), then, on heating, to nitrosohemochrome (a pink pigment).

The meat-packing industry has falsely claimed nitrite is used to prevent botulism (see also Inhibition of microbial growth).
 Several large meat processors produce processed meats without relying on nitrite or nitrate.

Historically, salt has been used for the preservation of meat. 
The salt-preserved meatproduct 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.

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.[13] Through this research, sodium nitrite has been found to give taste and color to the meat; inhibit lipid oxidation that leads to rancidity; with varying degrees of effectiveness for controlling growth of disease-causing microorganisms.[13] 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/taste. According to scientists working for the meat industry,[14] nitrite has improved food safety.[13] However, this view is widely disputed in the light of its ineffectiveness against botulism and the carcinogenic effects caused by adding nitrites to meat.[8]

Nitrite has the E number E250. Potassium nitrite (E249) is used in the same way. 
It is approved for usage in the EU, USA and Australia and New Zealand.

Color and taste
The appearance and taste of meat is an important component of consumer acceptance.
Sodium nitrite is responsible for the desirable red color (or shaded pink) of meat.
Very little nitrite is needed to induce this change.
It has been reported that as little as 2 to 14 parts per million (ppm) is needed to induce this desirable color change.
However, to extend the lifespan of this color change, significantly higher levels are needed.
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.[13] However, the mechanism underlying this change in taste is still not fully understood.[19]

Inhibition of microbial growth
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 which 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.[20] In some countries, cured-meat products are manufactured without nitrate or nitrite, and without nitrite from vegetable source. Parma ham, produced without nitrite since 1993, was reported in 2018 to have caused no cases of botulism.[8]

Sodium nitrite has had varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms.
Even though the inhibitory mechanisms for sodium nitrite are not well known, its effectiveness depends on several factors including residual nitrite level, pH, salt concentration, reductants present and iron content.[19] Furthermore, the type of bacteria also affects sodium nitrites effectiveness.[19] It is generally agreed upon that sodium nitrite is not considered 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.

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

Sodium nitrite is toxic.
The LD50 in rats is 180 mg/kg and its human LDLo is 71 mg/kg, meaning a 65 kg person would likely have to consume at least 4.6 g to result in a 50% chance of death.
To prevent intoxication, sodium nitrite (blended with salt) sold as a food additive in the USA 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.

Occurrence in vegetables
Nitrites are not naturally occurring in vegetables in significant quantities.
 However, nitrates are found in commercially available vegetables and a study in an intensive agricultural area in northern Portugal found residual nitrate levels in 34 vegetable samples, including different varieties of cabbage, lettuce, spinach, parsley and turnips ranged between 54 and 2440 mg/kg, e.g. curly kale (302.0 mg/kg) and green cauliflower (64 mg/kg).[36][37] Boiling vegetables lowers nitrate but not nitrite.[36] Fresh meat contains 0.4–0.5 mg/kg nitrite and 4–7 mg/kg of nitrate (10–30 mg/kg nitrate in cured meats).[35]

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

Adding nitrites to meat has been shown to generate known carcinogens such as nitrosamines; the World Health Organization (WHO) advises that each 50 g (1.8 oz) of "processed meats" eaten a day would raise the risk of getting bowel cancer by 18% over a lifetime; "processed meat" refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. 
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; 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.).

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.

Around 1970, it was found that ascorbic acid (vitamin C), an antioxidant, inhibits nitrosamine formation.
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.
The nitrosonium ion formed in acidic nitrite solutions is commonly mislabeled nitrous anhydride, an unstable nitrogen oxide that cannot exist in vitro.

Nitrate or nitrite (ingested) under conditions that result in endogenous nitrosation has been classified as "probably carcinogenic to humans" by International Agency for Research on Cancer (IARC).
The World Health Organization's review of more than 400 studies concluded, in 2015, that there was that there was sufficient evidence that "processed meats" caused cancer, particularly colon cancer.[8]

Sodium nitrite consumption has also been linked to the triggering of migraines in individuals who already suffer from them.

One study has found a correlation between highly frequent ingestion of meats cured with pink salt and the COPD form of lung disease. 
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.

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.

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.

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

Chemical reactions
Main articles: nitrite and nitrous acid
In the laboratory, sodium nitrite can be used to destroy excess sodium azide.

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.

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
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.

Nitrite Ion is a symmetric anion with equal N–O bond lengths. 
Nitrite is important in biochemistry as a source of the potent vasodilator nitric oxide. 
Nitrate or nitrite (ingested) under conditions that result in endogenous nitrosation has been classified as "Probably carcinogenic to humans" (Group 2A) by International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization (WHO) of the United Nations. 
Sodium nitrite is used for the curing of meat because it prevents bacterial growth and, as it is a reducing agent (opposite of oxidation agent), in a reaction with the meat's myoglobin, gives the product a desirable pink-red "fresh" color, such as with corned beef. 
This use of nitrite goes back to the Middle Ages, and in the US has been formally used since 1925. 
Because of the relatively high toxicity of nitrite (the lethal dose in humans is about 22 milligrams per kilogram of body weight), the maximum allowed nitrite concentration in meat products is 200 ppm. 
At these levels, some 80 to 90% of the nitrite in the average U.S. diet is not from cured meat products, but from natural nitrite production from vegetable nitrate intake. 
Under certain conditions – especially during cooking – nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens. 
However, the role of nitrites (and to some extent nitrates) in preventing botulism by preventing C. botulinum endospores from germinating have prevented the complete removal of nitrites from cured meat, and indeed by definition in the U.S., meat cannot be labeled as "cured" without nitrite addition. 
They are considered irreplaceable in the prevention of botulinum poisoning from consumption of cured dry sausages by preventing spore germination. 
Nitrite is a member of the drug class antidotes and is used to treat Cyanide Poisoning.

Description: A white to slightly yellow, granular powder, or white or almost white, opaque, fused masses or sticks; odourless. 
Solubility: Freely soluble in water; sparingly soluble in ethanol (~750 g/l) TS. 
Category: Vasodilator. Storage: Sodium nitrite should be kept in a well-closed container, protected from light. 
Additional information: Sodium nitrite is deliquescent in air. 
Even in the absence of light, it is gradually degraded on exposure to a humid atmosphere, the decomposition being faster at higher temperatures. 
Definition: Sodium nitrite contains not less than 98.0% and not more than 100.5% of NaNO2, calculated with reference to the dried substance.

§ 172.175 Sodium nitrite.
The food additive sodium nitrite may be safely used in or on specified foods in accordance with the following prescribed conditions:

(a) It is used or intended for use as follows:

(1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite does not exceed 10 parts per million (0.001 percent) in the finished product.

(2) As a preservative and color fixative, with or without sodium nitrate, in smoked, cured sablefish, smoked, cured salmon, and smoked, cured shad so that the level of sodium nitrite does not exceed 200 parts per million and the level of sodium nitrate does not exceed 500 parts per million in the finished product.

(3) As a preservative and color fixative, with sodium nitrate, in meat-curing preparations for the home curing of meat and meat products (including poultry and wild game), with directions for use which limit the amount of sodium nitrite to not more than 200 parts per million in the finished meat product, and the amount of sodium nitrate to not more than 500 parts per million in the finished meat product.

(b) To assure safe use of the additive, in addition to the other information required by the Act:

(1) The label of the additive or of a mixture containing the additive shall bear:

(i) The name of the additive.

(ii) A statement of the concentration of the additive in any mixture.

(2) If in a retail package intended for household use, the label and labeling of the additive, or of a mixture containing the additive, shall bear adequate directions for use to provide a final food product which complies with the limitations prescribed in paragraph (a) of this section.

(3) If in a retail package intended for household use, the label of the additive, or of a mixture containing the additive, shall bear the statement “Keep out of the reach of children”.

Sodium nitrite is harmful if inhaled or ingested and proper protection should be worn when handling the compound.

Sodium nitrite should be kept in closed bottles, away from light, moisture and oxygen-rich environment.

Heating sodium nitrite above 300 °C will cause it to decompose, leaving behind sodium oxide/hydroxide which can be safely disposed of.

Adding sodium percarbonate to sodium nitrite will convert it to sodium nitrate.


Many types of aqueous corrosion inhibitors are used to combat the corrosion of steel in various water and oil systems such as cooling water system and oil / gas production facilities respectively. 
Sodium nitrite is an anodic inhibitor and as the name implies, anodic inhibitors interfere with the anodic process (metal dissolution), and reduce the corrosion rate by suppressing the anodic reaction, through the formation or maintenance of a passive film on the metal surface.
[1 The performance of sodium nitrite as a passivator inhibitor of mild steel in semi-closed cooling water system seems to be markedly affected by the pH value of the solution. 
This can be attributed to the natural of passive film. 
Also the pH of the solution has been shown to play a key role in determining the corrosion mode of carbon steel .
Below a critical pH (pHcrit.), only localized corrosion is possible. This behavior arises because of the dependence of the formation and stability of the passive film of iron on pH. [2] 
The pHcrit. 
For the transition from general corrosion to passivity has been reported to be between 8 and 10.5, depending on the temperature and the concentration of ionic 

Performance Evaluation of Sodium Nitrite Corrosion
Inhibitor in Self Compacting Concrete
R. Dharmaraj1* and R. Malathy2

A kind of special concrete known for its flowing property and the mixture affixes under its self-weight. 
Henceforth under congested circumstance it obviates the difficulty of placing concrete moreover reducing the time in setting up large sections meanwhile affording increased strength and commanding durability characteristics than standard concrete. 
The major consequence facing all around is that durability concern with respect to corrosion of steel. 
The premature failures in concrete are caused due to this corrosion of steel. 
To improve a service life of concrete, corrosion inhibitors have been used as effective measures to inhibit corrosion. 
But there are numerous inhibitors were exists in the market. 
Only Sodium Nitrite has proven corrosion inhibiting capabilities simultaneously refine the mechanical properties of concrete. 
Therefore the presence of sodium nitrate in the self compacting concrete as the corrosion inhibiting admixture, the strength and corrosion resisting properties were studied by the dosage added 0%, 1%, 2%, 3%, 4% and 5%, by the weight of cement. 
Mix design for M25 grade of concrete according to BIS method (IS 10262:2009). 
Cement is replaced with consistent percentage of fly ash (40%). 
Then the standard concrete mix proportions were modified into SCC properties as per EFNARC specifications and different trail mixes were done. 
The investigation on the properties of self compacting concrete in spite of the effect of corrosion inhibiting admixture is done on the trial basis. 
The effect of Corrosion inhibiting admixture (a sodium nitrate based inhibitor) along with the properties of fresh concrete and the hardened concrete are determined. 
From the results it is proven that the self compacting concrete increases the strength of the concrete with accretion of inhibitor (sodium nitrite). 
Ultimately it was concluded that the compressive strength of cubes at 3% of sodium nitrite was increased strength by 8.8% in comparison with standard self compacting concrete (SN0) mix

The Influence of Different Levels of Sodium Nitrite on the Safety, Oxidative Stability, and Color of Minced Roasted Beef
Karolina M. Wójciak, Dariusz M. Stasiak * and Paulina K ˛eska

Abstract: This study focuses on collecting actual data on the workable possibility of reducing the technological use of nitrites in beef products according to the present trends in nutrition, especially in terms of European Union (EU) food law. 
Measurements of safety by technological (pH value, water activity, N-nitrosamine), microbiological, oxidative stability (thiobarbituric acid reactive substances, oxidation-reduction potential), and color parameter (CIE L*a*b*, total heme pigment and heme iron) methods were taken after production and storage. 
The roasted beef with a reduced inclusion level of sodium nitrite (75 mg/kg and below) was more vulnerable to lipid oxidation. 
The quantities of primary lipid oxidation products were related to the sodium nitrite inclusion level (50–150 mg/kg).
Clostridium spp., Staphylococcus aureus, and Listeria monocytogenes were not detected in any of the samples tested during all the experiments. 
The total count of Enterobacteriaceae increased with the decrease in sodium nitrite content, from log 2.75 cfu/g at the highest to log 6.03 cfu/g at the smallest addition of nitrite. The obtained results revealed that the addition of 100 mg/kg of sodium nitrite would be adequate for minced roasted beef, without significant unexpected effects on color, oxidative stability, and microbiological safety compared with the control (150 mg/kg). Keywords: sodium nitrite; meat products safety; lipid oxidation; pathogen bacteria; N-nitrosamines 

1. Introduction Meat products are a unique food form for many reasons. 
They form the basis of the diet of many people around the world, although there are others who prefer meatless diets for different reasons. Europeans consume a lot of meat. 
The annual consumption is estimated to be between 60 and 135 kg of meat and meat products (including 30–60 kg of pork) per capita. 
This is mainly due to the fact that meat is a rich source of protein. 
Meat products are a rich source of exogenous amino acids (phenylalanine, lysine, leucine, isoleucine, methionine, threonine, tryptophan, and valine) and relatively exogenous precursors (arginine and histidine) for the synthesis of nitrogen compounds of physiological importance, (for example, serotonin, nicotinic acid, carnitine, thyroxine, creatine, heme, and glutathione). 
They are the basic source of B vitamins (B1, B12, and B2) and vitamins A, E, C, and B3. 
Meat products are believed to be an essential source of many micro and macro elements (e.g., iron, zinc). 
However, Püssa [1] showed some toxic substances that unfortunately may be present in meat and meat products, including arsenic, cadmium, lead, polychlorinated biphenyls (PCBs), dioxins, aflatoxins, ochratoxins, ptaquiloside, phytanic acid, dichlorodiphenyltrichloroethane (DDT), leukotoxins, polycyclic aromatic hydrocarbons (PAHs), biogenic amines, botulinum toxin, bisphenol A, phthalates, and nitrites. 
These toxic substances are from various sources. 
Nitrites can react with hemoglobin to form methemoglobin, which lacks oxygen transport ability, and produce N-nitrosamines by reaction with secondary amines which are capable of mutagenic and carcinogenic actions [1]. 

Because of the potential risk of formation of carcinogenic substances in meat products, the reduction or total elimination of the addition of sodium/potassium nitrite from food products has been one of the main research areas in the field of meat science worldwide. 
Today, nitrite is used to meet consumer requirements with respect to product safety (protection against multiplication of Clostridium botulinum) and sensory characteristics connected with cured meats. 
Correspondingly, the process of meat curing has been traditionally coupled with processed meats in order to reach proper color, texture, flavor, safety, and shelf-life characteristics that make the products diverse. Current European Union (EU) regulations concerning the use of nitrite and nitrate differ with respect to both the method of curing used and the product that is cured. 
According to Directive 2006/52/EC of the European Parliament [2] and of the Council and Commission Regulation (EU) No 1129/2011 [3], all in all, 150 mg nitrite per kg is permitted to be inserted into all meat products plus 150 mg nitrate per kg for non-cooked meat products. 
Finally, maximum levels of 300 mg nitrite and nitrate per kg can be used for ripening ham production. 
In cooked meat products, no more than 150 mg nitrite per kg is allowed. 
However, the maximum allowed nitrite level is 100 mg/kg in the sterilized meat products.

When curing meat, nitric oxide is formed from sodium nitrite added to meat. 
The minimum addition of nitrite for obtaining a visible cured meat color is determined experimentally as approximately 25 mg/kg [4]. 
According to Sindelar and Milkowski [5], the limit of sodium nitrite in order to obtain the required cured meat flavor and oxidative stability is above 50 mg/kg. 
The influence of nitrite on the flavor of meats is well described, but the chemical movements are still unclear. 
Villaverde et al. [6] and Berardo et al. [7] presented the complicated but unclear consequences of curing on meat lipid and protein transformation. 
In addition, the nitrite promotes the formation of Strecker aldehydes, thus forming the overall sensory quality of cured meats. 
Therefore, the reduction of nitrite level in meat products should be carefully studied. 
Nitrite inhibits the growth of pathogenic bacteria such as Salmonella enterica serovar Typhimurium, Listeria spp., and Clostridium botulinum [8], which under anaerobic condition produces the most lethal neurotoxin. Nitrite in meat (50–150 mg/kg) can increase the pace of the development of various aerobic and anaerobic microorganisms. 
In January 2016, the Food Chain Evaluation Consortium discussed the requests of European Commission and inferred in the report that a fair inclusion level of 100 ppm of added nitrite would be adequate for the majority of products, without having a significant effect on color, flavor, and microbiological safety [9]. 
Nitrite is a multifunctional food additive in meat processing. On the one hand, the result of a previous study showed that nitrite use should be limited due to its potential negative influence on human health. On the other hand, some studies revealed the beneficial effect of nitrite on human health [10]. 
Considering the varied expectations of both food producers and consumers, it is important to pursue the impact of different amounts of sodium nitrite on the safety, oxidative stability, and the color of minced roasted beef to reduce or eliminate toxic substance from meat products. 
Therefore, the objective of the research was to collect physicochemical and microbiological data on the real demand of nitrites. 
These data will be useful for achieving advances in meat technology, especially on the ability to limit the use of nitrites according to EU health policy.

The increase in the number of micro-organisms while storage is one of the main agents that influences the quality of roasted, minced beef, leading to its spoilage as the consequence. 
It is crucial to provide meat products with a lower inclusion level of sodium nitrite with the same level of safety as that of products with the maximum level permitted. Gonzalez and Diez [21] have shown the effectiveness of nitrite (50–150 ppm) in lowering Enterobacteriaceae count in Spanish sausage. 
A lower inclusion level of nitrite is needed to develop color than to control the amount of bacteria. Nitrite can also inhibit the growth of several aerobic and anaerobic microorganisms such as pathogen C. botulinum and contribute to the management of other microorganisms including L. monocytogenes, and S. enterica serovar Typhimurium [22]. Salt (NaCl), besides controlling C. botulinum, co-operates with nitrite and other factors such as acidity, meat type, heat treatment. It enables effectively control of the outgrowth of spores and thus widely helps in controlling C. botulinum. 
Salt at 5% (wt/vol) was indicated to completely inhibit C. botulinum growth in its optimal growth conditions [23]. 
Nitrite is able to inhibit bacteria more effectively at low pH or higher acidity [24]. 
The characteristics of curing with nitrite that make it an effective antibotulinal compound depend on the interactions of nitrite with several other variables. The variables that nitrite interacts with include salt, pH, heat treatment, spore level, nitrite input level during manufacture, and residual nitrite amount in the meat [25]. 
The characteristics of the competing flora, accessibility of iron in the product, and other supplements present in the meat including ascorbate, erythorbate, phosphate, etc. are other additional factors [26]. Furthermore, cooking, curing, and storage temperatures are the other important factors. In the literature, we found that the impact of nitrate on controlling C. botulinum toxin production was restricted—nitrite at the amount of 50 ppm resulted in two toxic samples out of 110 tested, and nitrite levels above the amount of 50 ppm resulted in zero toxic samples [27]. 
This particular observation is in accordance with Lövenklev et al. [28], who discovered that the amount of 45 ppm sodium nitrite effectively suppressed C. botulinum gene representation. Cui et al. [29] used a combination of sodium nitrite and spice extracts and found that sage extract inhibits the growth of C. botulinum and clove and nutmeg can inactivate bacteria when combined with 10 ppm of sodium nitrite. 
Christieansa et al. [30] showed that a 47% reduction in the nitrite concentration provided the same sanitary effect against Salmonella and Listeria as the regulatory inclusion level in French dry-fermented sausage. The obtained results indicated that the concentration of nitrite does not affect the LAB count. For LAB, the results agree with other studies showing that Micrococcaceae and LAB were not greatly affected by nitrate and nitrite [21,22]. 
A residual nitrite level from 10 to 15 ppm is recommended as a reservoir for the regeneration of cured meat color (30–50 mg/kg meat). 
Ahn and Maurer [31] recorded pinking effects in oven-roasted turkey breasts with the addition of as little as 1 ppm of sodium nitrite. 
Heaton et al. [32] also recorded almost the same results in cooked turkey rolls, chicken rolls, and pork shoulder rolls. 
Moreover, the authors reported that sensory panelists noticed pinkness or even pink color in turkey, chicken, and pork rolls for 2, 1, and 4 ppm sodium nitrite samples, respectively. The authors also pointed out that meat products with higher pigment concentrations (pork) needed higher nitrite levels for panelists to observe the visual pinking effects. 
Deda et al. [33] assessed the color parameters of frankfurters produced with different levels of sodium nitrite and tomato paste. 
The authors showed that the amount of sodium nitrite added to the frankfurters can be reduced from 150 to 100 ppm when Sustainability 2019, 11, 3795 13 of 16 combined with 12% tomato paste without any negative effect on the quality parameter of the final product. 
Hayes et al. [34] proved that the amount of sodium nitrite could be reduced to 50 ppm when combined with 1.5% of tomato pomace powder with similar sensory qualities and microbiological stability compared to formulation with 100 ppm nitrite alone. 
Another property of nitrite is its ability to retard the oxidation process during storage period and the subsequent warmed-over and rancid flavors developed during thermal processing of meat and meat products [35,36]. The antioxidant activity of nitrite is attributed to the potential of nitric oxide to bind to and stabilize heme iron of meat pigments during the meat curing process. 
Nitric oxide, being a free radical, can also trigger lipid autoxidation by chelate free radicals including peroxyl radicals. 
The nitrite binds free irons and stabilizes the heme iron, which can reduce lipid oxidation by limiting prooxidant activity of iron. 
The our data show the effect of different inclusion levels of sodium nitrite (from 50 to 150 mg/kg) and storage time on the oxidative stability of the roasted beef (Table 3, Figure 3). Nitrite can form another antioxidant compound, for example, S-nitrosocysteine. Dethmers and Rock [37] stated that the addition of nitrite above the amount of 50 ppm to Thuringer sausage lowered the off-flavor development and bettered the flavor quality, whereas treatments with no nitrite added were believed to be the most rancid ones due to the poor flavor quality. 
Doolaege et al. [38] investigated the effects of different inclusion levels of sodium nitrite (40, 80, and 120 ppm) combined with different inclusion levels of rosemary extract (0, 250, 500, and 750 ppm) and reported that the concentration of sodium nitrite added to liver pate could be reduced to 80 ppm when rosemary extract is added at 250, 500, and 750 ppm concentrations without any negative effect on lipid oxidation and color parameters. 
A significantly higher ORP was observed for samples N_75 and N_50 than for samples N_150 and N_100 throughout the storage period. 
Samples treated with higher inclusion level of sodium nitrite (100–150 mg/kg) had decreased potential redox values compared to other samples by ≈18 mV (Table 3). Storage time (S) affected only ORP values (p < 0.001). In all study samples, a gradual decrease (p < 0.05) was shown at 7 days of storage, followed by a slight increase at 14 and 21 days of storage. 
According to Antonini and Brunoni [39], the ORP value tends to become lower at higher pH. 
In the our study, as pH decreased the ORP increased (Tables 1 and 3). 
The highest ORP values (N_75 and N_50) indicated that heme pigments in the ferric state had not stabilized the color of product [40], which confirmed the results of the ∆E showed on Figure 4. 
The dependence of OZB on ORP was observed—higher ORP values is connected with intensification of beef oxidation. 
More oxidative metabolism causes color changes, leading to darkening of the meat [41]; this is reflected in the decline in OZB values observed in this study. OZB was less susceptible to changes in the TBARS indicator (r = 0.213; p > 0.05). 

5. Conclusions 
Nitrite is difficult to replace as a preservative, because it can simultaneously perform many functions. 
The present study showed the real possibility of reduction in the use of nitrite in meat products. 
The obtained results revealed that 100 mg/kg of sodium nitrite added would be sufficient for minced roasted beef, without significant effects on color, oxidative stability, and microbiological safety as compared to control (150 mg/kg). 
A reduction in the addition of sodium nitrate by half and two-thirds resulted in a decrease in pH and water activity. 
More importantly, the lower nitrite inclusion level (50 and 75 mg/kg) caused an acceleration of oxidation processes (higher TBARS values and ORP) in the product and color deterioration during 21 days of chilling storage. 
Therefore, further studies are needed to investigate the complex effect of various reduced levels of nitrite and potential alternative compounds and/or technologies that can substitute nitrite.

Cooling water is an integral part of most of the chemi- cal process and many other industries. 
This contains aggres- sive ions which cause corrosion problems in boilers, con- densers, heat exchangers, pipe lines, economizers etc. 
Simulated Cooling Water (SCW) having composition 300 ppm Cl– , 351 ppm SO 2– , 37 ppm CO 2– , and 123 ppm HCO– represents cooling water in industry. 
Use of inhibitors in controlling corrosion in cooling water systems is the most convenient and economic method compared to others. 
Among numerous inorganic and organic inhibitors used in the last sixty years nitrite appears to be a promising oxidizing inhibitor for steel . 
It produces ferric oxide barrier on the surface of steel against corrosion. Tosun found ni- trite as the best inhibitor in effectiveness among chromate, molybdate, benzoate, ascorbic acid and orthophosphate in neutral aqueous media containing 100 ppm NaCl [5]. 
Nitrite is also effectively used as inhibition admixture in con- crete reinforcement [6–8]. Ramasubramanian reported the inhibition action of calcium nitrite on carbon steel in alka- line chloride containing media [9]. 
Synergistic inhibition action of nitrite in conjunction with chromate, molybdate, ascorbic acid, benzoate, ortho phosphate has been reported in the literature [9–12]. 
Most of the investigations on the inhibition effects of nitrite have been carried out in chloride free or in low chloride neutral or alkaline aqueous environ- ment in ideal condition.

The use of sodium nitrite (NaNO2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. 
The effectiveness of NaNO2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. 
The samples were tested in varying concentrations of NaNO2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). 
It was found that a concentration of 1000 ppm NaNO2, replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. 
Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. 
IC analyses indicated that NO2 does not easily oxidize to NO3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. 
Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths

Natrium nitrit [German]
Nitrito sodico [Spanish]
Sodium nitrite, 97+%, ACS reagent
Nitrite de sodium [French]
HSDB 757
Sodium nitrite solution, 40 wt. % in H2O
EINECS 231-555-9
NSC 77391
EPA Pesticide Chemical Code 076204
natrium nitrite
sodium nitrit
Sodium nitrite, 99%, extra pure, contains an anticaking reagent
Sodium nitrite (TN)
Sodium nitrite ACS grade
EC 231-555-9
INS NO.250
Sodium nitrite, AR, >=98%
Sodium nitrite, LR, >=98%
Sodium nitrite, analytical standard
Sodium nitrite, granular, 99.5%
Sodium nitrite, Trace metals grade
Sodium nitrite, 98.5%, for analysis
Sodium nitrite [UN1500] [Oxidizer]
Sodium nitrite, ACS reagent, >=97.0%
Sodium nitrite, 0.1M Standardized Solution
Sodium nitrite, p.a., ACS reagent, 99%
Sodium nitrite, 99.5%, super free-flowing
Sodium nitrite, ReagentPlus(R), >=99.0%
Sodium nitrite, 99.999% trace metals basis
Sodium nitrite, SAJ first grade, >=97.0%
Sodium nitrite, >=99.99% trace metals basis
Sodium nitrite, JIS special grade, >=98.5%
Sodium nitrite, purum p.a., >=98.0% (RT)
Sodium nitrite, puriss. p.a., ACS reagent, >=99.0% (RT)
Sodium nitrite, United States Pharmacopeia (USP) Reference Standard
Nitrite ion standard solution, 0.01 M NO2-, for ion-selective electrodes
Nitrite ion standard solution, 0.1 M NO2-, for ion-selective electrodes
Sodium nitrite, anhydrous, free-flowing, Redi-Dri(TM), ACS reagent, >=97%
Sodium nitrite, puriss. p.a., ACS reagent, reag. Ph. Eur., >=99%
Sodium nitrite, puriss., meets analytical specification of Ph. Eur., BP, USP, FCC, E 250, 99-100.5% (calc. to the dried substance)

•    Sodium nitrite, contains an anticaking reagent, extra pure, 99%
•    Sodium nitrite, for analysis ACS, 97+%
•    Sodium nitrite, 98.5%, for analysis
•    Sodium nitrite, 97+%, for analysis ACS
•    Sodium nitrite, for analysis
•    Sodium nitrite, for analysis ACS
•    Sodium Nitrite [for General Organic Chemistry]
•    Sodium nitrite, 99.99+% metals basis
•    Sodium nitrite, 99.999% metals basis
•    SodiumNitriteUsp
•    SodiumNitriteAr
•    SodiumNitriteGr
•    SodiumNitriteNaNO2
•    SodiumNitrite99%Min
•    SodiumNitriteExtraPure
•    SodiumNitriteFcc
•    SodiumNitriteUsp-27
•    Sodiumnitrite,98%
•    Sodium nitrite ACS reagent, >=97.0%
•    Sodium nitrite puriss. p.a., ACS reagent, reag. Ph. Eur., >=99%
•    SodiuM Nitrite, 99 Percent
•    SodiuM Nitrite, GR ACS
•    Sodium Nitrite (1 g) (AS)
•    SodiuM nitrite, for analysis ACS, 97+% 500GR
•    SodiuM nitrite, for analysis ACS, 97+% 5GR
•    SodiuM nitrite, for analysis, 98.5% 1KG
•    Sodium Nitrite, Crystal
•    Sodium nitrite, synthesis grade
•    Sodium nitrite, reagent grade, ACS
•    Sodium nitrite/ 99+%/ ACS
•    Sodium nitrite,99%,extra pure,contains an anticaking reagent

Sodium Nitrite
M. Abdollahi, M.R. Khaksar, in Encyclopedia of Toxicology (Third Edition), 2014
Background (Significance/History)
Sodium nitrite is similar in name and use to sodium nitrate. 
Both are preservatives used in processed meats, such as salami, hot dogs, and bacon. 
Sodium nitrite has been synthesized by several chemical reactions that involve the reduction of sodium nitrate. 
Industrial production of sodium nitrite is primarily by the absorption of nitrogen oxides into aqueous sodium carbonate or sodium hydroxide. 
Over the years, sodium nitrite has raised some concerns about its safety in foods, but it remains in use and there are indications that it may actually be healthy. 
Sodium nitrite was developed during the 1960s. 
In 1977, the US Department of Agriculture (USDA) considered banning it but the USDA’s final ruling on the additive came out in 1984, allowing its use. 
Studies in the 1990s indicated some adverse effects of sodium nitrite, for instance the potential to cause childhood leukemia and brain cancers. 
In the late 1990s, the National Toxicity Program (NTP) began a review of sodium nitrite and proposed listing sodium nitrite as a developmental and reproductive toxicant, but a report in 2000 by NTP proposed that sodium nitrite is not a toxic substance and removed it from the list of developmental and reproductive toxicants. 
It is now believed that it can help with organ transplants and leg vascular problems, while preventing heart attacks and sickle cell disease.

Sodium Nitrite/Sodium Nitrate
Sodium nitrite is the most important cure additive responsible for the typical color and flavor associated with cooked cured meats. 
Sodium nitrite also provides oxidative stability to meat by preventing lipid oxidation and helps in controlling the development of warmed-over flavor in cooked, stored meats. 
Nitrite also serves as a vital bacteriostatic agent for control of the outgrowth of C. botulinum, particularly under conditions of product mishandling. 
However, addition of sodium nitrite to meat and meat products is highly regulated owing to the possible risk of formation of N-nitrosamine.

In Canada, maximum allowable limit for the use of sodium nitrite, potassium nitrite, or their combinations in preserved meat and meat products (e.g., hams, loins, shoulders, cooked sausages, and corned beef) is 200 ppm (20 g per 100 kg; equivalent to 0.32 oz nitrite per 100 lbs raw batch). 
However, the industry has taken steps to reduce the level of nitrite used in such products to 120–180 ppm. 
In pumped bacon, in-going nitrite levels usually do not exceed 120 ppm (i.e., 0.19 oz nitrite per 100 lbs meat) owing to the possible risk of N-nitrosamine formation. 
These regulated levels are based on the amounts used in the product formulation before any cooking, smoking, or fermentation and are usually added as a cure salt, such as Prague powder.

In the US, the Food Safety and Inspection Service (FSIS) regulations permit the use of sodium or potassium nitrite in all products except bacon at the following levels: 2 lb in 100 gallons of pickle at 10% pump or 200 ppm; 1 oz for each 100 lb of meat (60 g in 100 kg) in dry cure; and 0.25 oz per 100 lb meat or 156 ppm maximum in comminuted and (or) meat by-products. 
For immersion-cured and dry-cured bacon, in-going nitrite level limits according to FSIS are 120 and 200 ppm, respectively. 
Residual nitrite levels in the finished pumped bacon cannot exceed 40 ppm.

Use of sodium or potassium nitrate as a curing agent is limited to some specialty products that require a long cure, such as dry-cured country ham and dry or semidry sausages. 
For such specialty products produced in Canada, a maximum of 200 ppm of nitrate may be used in addition to the 200 ppm of nitrite. 
In the US, FSIS regulations permit the use of 3.5 oz of nitrate in 100 lb of meat (215 g per 100 kg) in dry-cured country ham, 700 ppm nitrate in pickle cure, and 2.75 oz of nitrate in 100 lb (170 g per 100 kg) chopped meat and (or) meat by-product.

Sodium Nitrite
Sodium nitrite is an odorless, white or slightly yellow, hygroscopic and air-sensitive solid (it slowly oxidizes to nitrate), having both reducing and oxidizing properties. 
It presents a fire risk when in contact with reducing materials; for example, it is liable to render any organic matter (wood, paper and textiles) dangerously combustible when dry. 
It is decomposed by acids (even weak acids) with evolution of a brown mixture of nitrogen oxides (NOx). 
It is very toxic and dangerous to the environment, and it is an irritant and harmful substance that may damage the cardiovascular and central nervous systems. (See Nitrates and Nitrites.)
Nitrates and nitrites are used in cured meat products, to control the growth of microorganisms, particularly to avoid the development of Clostridium botulinum, and also to serve as color and flavor fixatives. When added to meat, nitrate and nitrite react with the myoglobin and hemoglobin present in the trapped red blood cells, eventually producing nitric oxide myoglobin. 
After curing, almost all the nitrate and nitrite have reacted with the meat components, and only a very small residual amount of nitrite remains. 
The FDA allows the use of sodium nitrite in smoked cured fish products (from 10 to 200 μg g−1) and in meat-curing preparations (< 200 μg g−1, mixed with sodium nitrate, FDA 172.175).
In the stomach, nitrite can produce dangerous carcinogenic nitrosamines; however, these reactions are inhibited in the presence of phenolic antioxidants, ascorbic acid, or other substances that are also added to food or are present in fruit and fresh vegetable juices that may be consumed with the cured meat. 
Furthermore, nitrite is naturally present in saliva, in concentrations higher than those found in cured meat products, and lettuce, spinach, beets, and many other vegetables contain nitrate, which is reduced in the mouth to nitrite by the action of bacteria. 
Therefore, the risks associated with the use of nitrate and nitrite in cured fish and meat products seem to be very small, whereas the benefits are large.

Sodium nitrite is a multifunctional food additive, responsible for the characteristic colour and flavour associated with cured meats and at the same time providing protection against growth and toxin formation by C. botulinum in cured meats subjected to temperature abuse. 
The exact mechanism of botulinal inhibition by nitrite is not known. 
However, its efficacy depends on complex interactions involving pH, salt, heat treatment, storage temperature and time, and not least the composition of the food matrix. 
It has been shown that nitrite interacts with nitrogenous compounds to form carcinogenic nitrosamines, and that intestinal bacteria mediate the formation of nitrosamines in the body. As a result, in recent years consumer and regulatory pressure has mounted to reduce the levels of nitrite in processed meats. 
In an attempt to produce a ‘healthier’ food product, the dangers of toxin formation by C. botulinum should not be overlooked, especially as hazards associated with ingestion of BoNT are greater than those associated with nitrites. C. botulinum in cured meat products is primarily controlled by refrigeration and the use of nitrite should be considered a safeguard against toxin production, should good refrigeration control not be maintained.

Sodium Nitrite and Sodium Nitrate
Sodium nitrite (NaNO2) and sodium nitrate (NaNO3), also known as curing salts, are added at low levels (usually 120–200 ppm) and provide several attributes. 
The main function is to suppress C. botulinum spore germination. The active compound is nitric oxide (NO). 
Only a very small amount is needed and using the salt form provides an easy and efficient way of introducing the active compound to the meat (i.e., NO gas can be introduced as well, but it is a much more expensive process).

The second function is to help develop the typical pink cured-meat color. 
Again, the active compound is NO. This pink color is very different from the brown color of a cooked product such as chicken/turkey leg meat. 
This can be described as the difference between home-cooked turkey dark meat (e.g., thigh meat) which is brown and a turkey ham product which appears pink. 
This is a reaction between the myoglobin and NO which initially forms nitrosomyoglobin and later with heat, the stable nitrosohemochrome. 
The third function is to help protect against lipid oxidation. 
Nitrite has antioxidant capabilities that can help prolong the shelf life of cooked meat products which are sensitive to oxidation.

Adding nitrite also helps in the development of some unique flavor notes. 
The amount of nitrite permitted in meat products is heavily regulated because at high levels it can be toxic. 
It is very important to note that processed meat products are not necessarily a high source of nitrite in our diet. 
In comparison, green vegetables such as celery have levels of about 300 ppm nitrate. 
In addition, bacteria in human saliva and in the gut are capable of producing even higher levels of nitrite. 
Nitrite added to meat products is depleted over time, especially during cooking, and a frankfurter with an initial 150-ppm NaNO2 level will end up with about 20–40 ppm or less at the point of purchase. Overall, it is estimated that meat products contribute only 10%–20% of the total nitrite in our diet (Sindelar and Milkowski, 2012). 
There is also a concern in products heated to high temperatures (e.g., bacon) that residual nitrite could react with secondary amines to form nitrosamine compounds, which are potential carcinogens. 
Therefore, in North America for example, the use of an added curing accelerator (e.g., 500 ppm ascorbate) has been mandated in such products to ensure a fast conversion of nitrite to nitric oxide. This minimizes the chance of nitrosamine formation when the product is exposed to high temperatures (frying at >100°C). 
The use of nitrite in processed meat products and its safety has been reviewed by Cassens (1990), Honikel (2008), and by Sindelar and Milkowski (2012).

Sodium nitrite is a multifunctional food additive, responsible for the characteristic color and flavor associated with cured meats and at the same time providing protection against growth and toxin formation by C. botulinum in cured meats subjected to temperature abuse. 
The exact mechanism of botulinum inhibition by nitrite is not known. 
Its efficacy depends on interactions involving pH, salt, heat treatment, storage temperature and time, and the composition of the food matrix. 
It has been shown that nitrite interacts with nitrogenous compounds to form carcinogenic nitrosamines and intestinal bacteria mediate the formation of nitrosamines in the body. 
As a result, in recent years, consumer and regulatory pressure has mounted to reduce the levels of nitrite in processed meats. 
The maximum concentration of sodium nitrite (NaNO2) in meat products typically is 150 mg kg–1. C. botulinum in cured meat products is primarily controlled by refrigeration and the use of nitrite. The control measure to apply is the addition of a sufficient quantity of nitrite salt (defined by the sodium nitrite (NaNO2) concentration).

What is the law regarding the labelling of nitrites/nitrates?
Foodstuffs containing nitrites/nitrates must comply with both the labelling provisions for food as laid down in Regulation (EU) No.1169/2011 as amended and with the more specific labelling requirements for food additives as laid down in chapter IV of Regulation (EC) No.1333/2008 on food additives. Regulation (EU) No. 1169/2011 requires the labelling of additives in the list of ingredients on pre-packaged foodstuffs by:

a) the functional class of the additive and
b) the specific name or designated E number

Therefore, for sodium/potassium nitrite, the following should appear on the label:

Preservative: Sodium nitrite, Potassium nitrite or
Preservative: E250, E249
The same rules apply to the use of sodium or potassium nitrate in foods (E 251 and E 252 respectively).

What must I consider if I want to remove nitrite/nitrate from my meat products?
If you are thinking of removing nitrite/nitrate from your meat product then you have a responsibility to ensure that the reformulated meat product is safe during its whole shelf life under reasonable conditions of consumer misuse. You must also ensure that the new product is in compliance with the laws governing additive usage and the laws governing food labelling. Overall, your label must not mislead the consumer to the extent that they buy your product in preference to similar products. Finally you must be able to provide all necessary evidence demanded by the competent authorities who are charged with ensuring compliance with the food law.

Can I use ingredients that are also sources of nitrite/nitrate to replace sodium or potassium nitrite/nitrate?
You cannot use ingredients that are also a source of nitrite/nitrate if used for the intended technological purpose of preservation or colouring in the final food. Such use would be considered a deliberate use of a food additive.

The use of nitrates and nitrites must comply with the food additives legislation, including the conditions of use laid down in Annex II part E to Regulation (EC) No. 1333/2008 as amended as well as the purity criteria in the Annex to Regulation (EC) No. 231/2012. The use of ingredients that are also sources of nitrite/nitrate, such as vegetable extracts or fermented vegetable broths, has been discussed on a number of occasions at the Commission working party on food additives and also at the EU Standing Committee on the Food Chain and Animal Health. On these occasions it was agreed by the Commission and all Member States, that such a practice would be a deliberate use of a food additive if used for the intended technological purpose of preservation or colouring in the final food.

Nitrites added to food for preservation or colouring purposes, via other ingredients like vegetable extracts/fermented broths would not currently be permitted by Regulation (EU) No. 1333/2008 as these extracts have not been approved as preservatives and their use would also not comply with the current purity criteria laid down in Regulation (EC) No. 231/2012.

Further information on these two standing committee decisions can be found at the following links: agenda item 4 agenda item 5

In September 2018 a further opinion was issued on use of vegetable extracts rich in constituents capable of performing a technological function. This opionion:

reconfirmed the validity of the previous 2006 and 2010 statements
stated that the scope of both statements is not limited only to (fermented/non-fermented) extracts containing high levels of nitrate/ nitrite but it shall be generally applicable to all plant extracts which, when added to foods, achieve a level of constituents (or their precursors) capable of performing a technological function in foods
stated that such use of extracts that deliver a technological function (e.g. preservative, antioxidant, stabiliser (colour stabiliser) etc.) in foods to which they are added is deemed a deliberate use as a food additive

Consequently, such use is deemed to meet the definition of a food additive and so it must comply with the conditions set out in the food additive legislation (including relevant specifications) and be labelled in accordance with the appropriate provisions for labelling of food additives

In addition, a number of plant extracts can perform both flavouring and additive functions. When flavourings have a technological function as food additives, the food additive legislation shall apply. In this case the extracts cannot be claimed to be used as flavourings.

Read the full opinion

What are the restrictions on the use of the word ‘natural’ on the food label of a meat product where nitrite has been removed?
The word “natural” is often used as a marketing term by food businesses and is currently not defined in legislation governing foodstuffs. However, general food legislation places on obligation on food businesses to ensure that the labelling, advertising and presentation of food, and the information made available about it through whatever medium, should not mislead consumers.

More specifically, the legislation requires that the labelling and methods used must not be such as could mislead the consumer to a material degree by suggesting that the foodstuff possesses special characteristics when in fact all similar foodstuffs possess such characteristics. A food business operator must be able to substantiate any claim made by them in relation to their product.

Therefore, in order not to mislead the consumer and thereby breach the labelling legislation the use of the word ‘natural’ would have to be in keeping with a general understanding of the meaning of that word in the context of food by the majority of consumers and cannot be used to imply that the food is different if all similar foods possess the same characteristics.

The FSAI has produced a guidance document for the use of food marketing terms including the term ‘natural’.

Can I use the word ‘natural’ in my ingredients declaration?
Legislation on flavourings sets out the requirements for use of the word ‘natural’ in relation to flavourings used in foodstuffs. For general ingredients, there is no definition of the word natural as discussed above. However, the labelling of foods requires that the labelling and methods used must not be such as could mislead the consumer to a material degree by suggesting that the foodstuff possesses special characteristics when in fact all similar foodstuffs possess such characteristics. Where ingredients do not possess special characteristics when compared with similar ingredients in other foodstuffs, then the word “natural” should not be used except where it is specifically permitted by legislation e.g. ‘natural flavouring’. Further information on the use of the term ‘natural’ can also be found in the FSAI's guidance document on food marketing terms.

Will my product be safe if I take out the nitrite?
Safety cannot be taken for granted unless a full validation of the new preservation system in the food is carried out. Nitrate has been traditionally used to prevent meat products from causing botulism caused by the harmful bacterium, Cl. botulinum. The removal of nitrite can be likened to the removal of a hurdle to the growth of Cl. botulinum. To maintain the safety of the food, another similar hurdle must be used to replace nitrite or otherwise the ‘height’ of the remaining hurdles has to be increased to prevent Cl. botulinum from growing. For example, to reinstate the safety of the food you may have to reduce the shelf life and/or increase the salt level (and therefore increase the water activity: Aw) and/or decrease the pH and/or add a different preservative. In effect you will have to reformulate the product, validate the shelf life and readjust the HACCP system to ensure the food can be manufactured safely on a consistent basis.

A useful document was produced by CCFRA in 2009 called “The manufacture of vacuum and modified atmosphere packaged chilled foods: a code of practice. 2nd edition”, which provides good guidance to manufacturers.

What is botulism?
Clostridium botulinum is a bacterium that exists in soils and is found throughout the environment. It produces spores which have great resistance to heat and chemical disinfectants. Cl. botulinum can be found in many raw foods including meat and is capable of producing a potent neurotoxin (poison that affects the functioning of brain and nerves) as it grows. The neurotoxin can kill at very low levels if victims are unable to seek immediate treatment. This condition is known as botulism.

For the purposes of this FAQ there are two main forms of Cl. botulinum called Type I and Type II. Type I Cl. botulinum spores are the most heat resistant but cannot grow below 10ºC. Type II Cl. botulinum spores are less heat resistant than Type I spores but can grow at temperatures as low as 3ºC. Both types of Cl.botulinum do not thrive in the presence of air and are therefore considered strict anaerobes.

How does nitrite prevent botulism?
Nitrite, in combination with salt and pH, is used in cured meats to ensure their safety with respect to a number of pathogens including Cl. botulinum. To cause illness, spores of Cl. botulinum have to be able to germinate and then grow in the meat product until a point at which botulinum toxin is produced by the bacteria. Nitrite exerts a concentration-dependent antimicrobial effect in meat products, including inhibition of the outgrowth of spores of Cl. botulinum. The antimicrobial effect is also pH-dependent, increasing ten-fold for each unit fall in pH. In its review of nitrite, the EFSA Biohazard Panel in 2003 concluded that between 50-150 mg/kg nitrite is necessary to inhibit the growth of Cl. botulinum. The panel concluded that the ingoing amount of nitrite into the product was the important preservation factor.

What must I do to satisfy the competent authorities that my product is safe and labelled correctly, if I remove the sodium or potassium nitrite/nitrate from my meat product and replace it with an alternative ingredient that is also a source of nitrite/nitrate?
The competent authorities are the government bodies charged with ensuring compliance with the food law. Where sodium or potassium nitrite/nitrate has been removed from the meat product and replaced by an alternative ingredient that is also a source of nitrate/nitrite, the competent authority will require the food business operator to prove that the alternative ingredient is not having a preservative effect in the final product. The competent authority may request inter alia:

(a) Full analytical results showing the levels of nitrate/nitrite in the meat product at the start and end of shelf life and the variability in those levels over several batches 

(b) Demonstrable evidence that the alternative ingredient is not providing a preservative effect and is not being added for the purposes of colouring the final meat product

If (b) above is demonstrated to the satisfaction of the competent authorities the food business operator (FBO) will also be required to provide at least the following information to verify that the reformulated meat product is still safe and can be produced safely on a consistent basis:

(c) A full documented hazard analysis showing the major chemical, biological and physical hazards relevant to the product. If sodium or potassium nitrite/nitrate is removed from a meat product then Cl. botulinum must be one of the hazards considered

(d) A full documented validation study to support the safety of the product throughout the applied shelf-life, taking into account all the hazards including Cl. botulinum and any anticipated levels of consumer abuse, like storage of chilled meats in domestic refrigerators at temperatures above 5ºC.

The FSAI's Guidance Note No.18 - Validation of Product Self-life (Revision 2), pg 27 Section, has further information on establishing the study conditions.

(e) Identification of Critical Control Points at the production steps critical to ensuring the safety of the food, establishment of suitable critical limits based on the validation data used for shelf life determination and application of appropriate corrective actions to ensure food safety should the critical limits be exceeded
(f) Full monitoring data to verify the functioning of the HACCP system

(g) Documentation relating to the HACCP system

In the context of impact on human health, nitrite/nitrate and related nitrogen species such as nitric oxide (NO) are a matter of increasing scientific controversy. 
An increase in the content of reactive nitrogen species may result in nitrosative stress—a deleterious process, which can be an important mediator of damage to cell structures, including lipids, membranes, proteins and DNA. 
Nitrates and nitrites are widespread in the environment and occur naturally in foods of plant origin as a part of the nitrogen cycle. 
Additionally, these compounds are used as additives to improve food quality and protect against microbial contamination and chemical changes. 
Some vegetables such as raw spinach, beets, celery and lettuce are considered to contain high concentrations of nitrates. 
Due to the high consumption of vegetables, they have been identified as the primary source of nitrates in the human diet. 
Processed meats are another source of nitrites in our diet because the meat industry uses nitrates/nitrites as additives in the meat curing process. 
Although the vast majority of consumed nitrates and nitrites come from natural vegetables and fruits rather than food additives, there is currently a great deal of consumer pressure for the production of meat products free of or with reduced quantities of these compounds. 
This is because, for years, the cancer risks of nitrates/nitrites have been considered, since they potentially convert into the nitrosamines that have carcinogenic effects. 
This has resulted in the development and rapid expansion of meat products processed with plant-derived nitrates as nitrite alternatives in meat products. 
On the other hand, recently, these two ions have been discussed as essential nutrients which allow nitric oxide production and thus help cardiovascular health. 
Thus, this manuscript reviews the main sources of dietary exposure to nitrates and nitrites, metabolism of nitrites/nitrates, and health concerns related to dietary nitrites/nitrates, with particular emphasis on the effect on nitrosative stress, the role of nitrites/nitrates in meat products and alternatives to these additives used in meat products.

Keywords: nitrites/nitrates, food, health effect, nitrosative stress, processed meat
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1. Introduction
Nitrate and nitrite ions are widespread in the environment and occur naturally in plant foods (vegetables) and water. 
The contribution of drinking-water to nitrate intake is usually low (less than 14%). 
However, due to the use of inorganic fertilizer, nitrate levels in water resources have increased in many places of the world, recently. 
In this context, in a situation where nitrate concentrations in drinking-water are below 10 mg/L, food (mainly vegetables) will be the main source of nitrate for the human. 
In the reverse situation, when the nitrate level in drinking-water is high (exceeding 50 mg L−1), water will definitely be the main source of exposure to nitrates [1,2].

Nitrates/nitrites can also be used as additives in food of animal origin. 
Nitrites (sodium nitrite—E249, potassium nitrite—E250) and nitrates (sodium nitrate—E251, potassium nitrate—E252) are authorized as food additives in the European Union under Commission Regulation (EU) No 1129/2011. 
They are used in food to stabilize processed meat and cheese. 
The regulation determines the maximum amount of nitrites and nitrates that may be added as a food additive during food processing. 
The amount of nitrite permitted for use in processed meat is currently 150 mg kg−1, with the exception of sterilized meat products for which the limit is 100 mg kg−1. 
The addition of sodium nitrate is allowed only in uncooked meat, to a maximum amount of 150 mg kg−1. 
Nitrites can also be present in dairy products from exogenous sources. 
The maximum concentration of nitrite allowed in the regulation for cheese is 150 mg kg−1.

Due to these sources of nitrates/nitrites, humans are exposed to these compounds. 
Some studies have estimated exposure to nitrites and nitrates [3,4,5]. 
According to the European Commission’s former Scientific Committee for Food (SCF) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the current acceptable daily intake (ADI) for nitrites are 0.06 and 0.07 milligrams per kilogram of body weight per day, respectively. 
In the case of nitrates, both organizations establish the ADI at 3.7 mg/kg bw/day.

Nitrate intake with food is associated with some health risks. When these compounds are consumed, about 60%–70% is easily absorbed and rapidly excreted in urine. 
In humans, about 3% of nitrate appears in urine as urea and ammonia. 
Nitrates may also survive passage through the stomach and enter the circulatory system. 
A variety of highly bioactive reactive nitrogen oxide species are formed under acidic gastric conditions or in blood and tissues. 
These may be involved in the generation of nitrosamines of toxicological importance when there are secondary amines present in the stomach [6]. 
According to Ding et al. [6], the presence of dietary antioxidants inhibits the generation of nitrosamines. 
The process of nitrosamine formation was completely inhibited when the molar ratio of antioxidants and nitrite was higher than 2:1.

This manuscript on nitrates and nitrites in food will review the main sources of dietary exposure to nitrates and nitrites, metabolism of nitrites/nitrates, health concerns related to dietary nitrites/nitrates, the role of nitrites/nitrates in meat products and alternatives to these additives used in meat products.

A systematic and comprehensive article retrieval strategy that provided a general impression of the risk for nitrosative stress and benefits due to nitrate or nitrite consumption was conducted. The Web of Science was searched for articles of studies assessing the relationship between the risk of cancer the nitrate or nitrite consumption. 
Many relevant articles were obtained by combing the keywords (nitrate, nitrite, risk of nitrosative stress, cancer) in a more detailed retrieval strategy. Moreover, a manual search of the references of relevant articles has been done.

What are nitrites/nitrates? Why are they present in food?
The salts of nitrite and nitrate are commonly used for curing meat and other perishable produce. 
They are added to food to preserve it and also help hinder the growth of harmful microorganisms, in particular Clostridium botulinum, the bacterium responsible for life-threatening botulism. 
Nitrites, together with nitrates, are also added to meat to keep it red and give flavour, while nitrates are used to prevent certain cheeses from bloating during fermentation. 

Nitrate is found naturally in vegetables, with the highest concentrations occurring in leafy vegetables like spinach and lettuce. 

It can also enter the food chain as an environmental contaminant in water, due to its use in intensive farming methods, livestock production and sewage discharge.

What happens to nitrites/nitrates in the body?
In humans, nitrite and nitrate from food are rapidly absorbed by the body and, for the most part, excreted as nitrate.
Some of the nitrate absorbed by the body is recirculated through salivary glands and part of it is converted by mouth bacteria into nitrite. 
Absorbed nitrite can oxidise haemoglobin to methaemoglobin, an excess of which reduces the ability of red blood cells to bind and transport oxygen through the body. 
Nitrite in food (and nitrate converted to nitrite in the body) may also contribute to the formation of a group of compounds known as nitrosamines, some of which are carcinogenic.

Why did EFSA re-evaluate nitrites/nitrates added to food?
The European Commission has asked EFSA to re-evaluate by 2020 all additives authorised before 20 January 2009.
As part of this programme, EFSA has re-assessed the safety of sodium and potassium salts of nitrite (E 249-250) and nitrate (E 251-252) in two scientific opinions published in June 2017.
The current acceptable daily intakes (ADIs) for nitrite, set by the European Commission’s former Scientific Committee for Food (SCF) in 1997 and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2002, are 0.06 and 0.07 milligrams per kilogram of body weight per day (mg/kg bw/day), respectively. 
For nitrate both bodies set the ADI at 3.7 mg/kg bw/day

How did EFSA re-assess the safety of nitrites and nitrates?
EFSA’s Panel on Food Additives and Nutrient Sources Added to Food (ANS) based its assessment on previous evaluations, new scientific literature, and information provided following public calls for data.

The experts were able to derive an ADI for nitrate as they did not consider it to be genotoxic or carcinogenic (for substances that are potentially damaging to DNA or may cause cancer no safe level can
be established). The panel considered the most relevant effect for setting a safe level was elevated blood concentrations of methaemoglobin, caused by nitrite converted from nitrate in saliva (see above). 
Based on this effect, the panel concluded that the ADI set by the SCF (1997) was sufficiently protective of public health.

The panel calculated an ADI of 0.07 mg/kg bw/day, corresponding to the safe level established by JECFA and close to the slightly more conservative current ADI of 0.06 mg/kg/bw/day derived by the SCF. 
As for nitrate, this is based on increased methaemoglobin levels in the blood following consumption as a food additive.

What were EFSA’s findings on nitrosamines?
Nitrites – including when used as food additives – contribute to the formation of a group of compounds known as nitrosamines, some of which are carcinogenic.
Applying a number of conservative (i.e. worst-case scenario) assumptions, the panel concluded that the formation of nitrosamines in the body from nitrites added at approved levels to meat products was of low concern for human health.
The panel further noted that nitrite unintentionally present in meat products from other sources such as environmental contamination can also contribute to the formation of nitrosamines. 

EFSA’s experts concluded that these levels of nitrosamines might give rise to potential health concerns but that more research was needed to address uncertainties and knowledge gaps in this complex area.

What were the main conclusions?
Based on the available evidence, EFSA’s experts concluded that existing safe levels for nitrites and nitrates added to meat and other foods are sufficiently protective for consumers. 
Using more realistic data (i.e. actual concentration levels in food), the experts estimated that consumer exposure to nitrate solely from
its use as a food additive was less than 5% of the overall exposure to nitrate in food, and did not exceed the ADI. 
For nitrites used as food additives, experts estimated exposure to be within safe levels for all population groups, except for a slight exceedance in children whose diet is high in foods containing these additives.
If all sources of dietary nitrate are considered (food additives, natural presence in food and environmental contaminants), the ADI may be exceeded for individuals of all age groups with medium to high exposure. 
Nitrite exposure from all dietary sources may exceed the ADI for infants, toddlers and children with average exposure, and for highly exposed individuals of all age groups.

What did the panel recommend?
To reduce uncertainties, the panel made several recommendations, including:
additional studies to measure the excretion of nitrate into human saliva, its conversion to nitrites, and the resulting methaemoglobin formation;
„further studies on the levels of nitrosamines formed in different meat products based on known amounts of added nitrites/nitrates;
„large-scale epidemiological studies on nitrite, nitrate and nitrosamine intake and risk of certain cancer types.

What other work has been done in this area?
The SCF and JECFA have reviewed nitrite and nitrate added to food on several occasions, which led to the setting of the current ADIs. 
In 2010, EFSA’s ANS Panel issued a statement on nitrites in meat products considering data from Denmark, which did not lead EFSA to revise the existing ADI. 
EFSA’s Panel on Contaminants in the Food Chain (CONTAM) has produced three opinions relevant to nitrites and nitrates, none of which proposed a revision of the ADIs previously set by the SCF and JECFA:

In 2008, the CONTAM Panel assessed the risks and benefits to consumers from nitrates in vegetables.
It concluded that the beneficial effects outweighed potential health risks from exposure to nitrate through vegetables, and that the average consumer would not exceed the ADI.


„In its 2009 opinion on nitrites as undesirable substances in animal feed, the panel concluded that the low nitrite levels in fresh animal products did not raise any concern for human health.
In 2010, a further opinion was delivered on the potential health risks for infants and young children from naturally occurring nitrate in leafy vegetables, in which the panel concluded that levels of nitrate in these vegetables are not of health concern for most children.

The International Agency for Research on Cancer (IARC) re-evaluated data available on nitrite and nitrate in 2010, but did not comment on the ADIs set previously by other organisations. 
The IARC evaluation includes a review of the effects of ingested nitrate in experimental animals and in humans arising from epidemiological studies.

In 2015, IARC classified processed meat as a carcinogenic hazard to humans (Group 1), with the formation of carcinogenic nitrosamines as one contributing factor. While IARC assesses the carcinogenic properties of substances, i.e. the potential hazard they pose, EFSA also evaluates the likelihood and level of exposure for different population groups in its risk assessments.

What happens next?
EFSA’s scientific advice will inform risk managers in the European Commission and Member States who regulate the safe use of nitrites and nitrates as food additives as well as their overall levels in food in the EU.

Acceptable daily intake – an estimate of the amount of a substance in food or drinking water that can be consumed over a lifetime without presenting an appreciable risk to health. 
It is usually expressed as milligrams of the substance per kilogram of body weight and applies to chemical substances such as food additives, pesticide residues and veterinary drugs.

Exposure – concentration or amount of a particular substance that is taken in by an individual, population or ecosystem in a specific frequency over a certain amount of time. 
When experts assess consumers’ dietary exposure to a chemical substance, they combine data on its concentrations in food with the quantity of those foods consumed. 
Children are often more exposed to substances because of their higher food consumption levels relative to their body weight.

The food additives Sodium Nitrate (INS 251) and Sodium Nitrite (INS 250) has a primordial role in the cure process of the meat and also has the conservative performance, at the same time imparting characteristics such as taste, texture, color and essence to the cured meat, making it more attractive to consumers. 
The use of these curing salts in the meat processing industry is widely spread, however, its use have been questioned because the ingestion in excess and under environmental specific conditions, nitrite can suffer chemical reactions, that unchains the production of n-nitroses carcinogenics compounds. 
As a result of a reaction between nitrous acids and secondary amines. 
Due to this possible reaction, the nitrite is considered a food additive with carcinogenic potential for human health. 
On the other hand, more recently, it was reported various beneficial physiological effects of nitric oxide, from decomposition of nitrate or nitrite about the cardiac and respiratory systems, by the ingestion of nitrate and nitrite in human feeding with adequate fractions. 
In this context, an important control step in the process of meat products is the weight of the curing salts, that interferes directly in the content residual nitrite of the final product. 
The goal of this project was to quantify the content of nitrate, nitrite and total residual nitrite and reduction percentage of these compounds of fresh sausage swine meat (FSSM) during different steps of the product processing in one facility meat beneficial of meat and meat products situated in the city of Campo Magro (State of Paraná). 
It was performed sausage samples, soon after the meat dough is done and out of the processor, and after 48 hours of the stuffed meat dough, kept refrigerated. 
The collected samples were sent to laboratory for analysis of nitrate and nitrite. 
The results have shown that the content of final residual nitrite (134,91ppm) it was under the Brazilian legislation limit (150ppm). 
In 48 hours, there was a reduction of 15,06% (90,35-76,74ppm) of nitrate, 69,15% (188,55-58,16ppm) of nitrite and 51,62% (278,90-134,91ppm) of the nitrate + nitrite combination added. 
The residual nitrite content of the product showed some conformity with the current legislation. 
The weight control and the added curing salt is a critical step of the processing of cured meat products such as the sausage, the factory that produces these meat should adopt methods that guaranties it’s additives residual contents do not overcome the limits of the legislation. 
This provides microbiological safety to the final product and preserves consumer health.

Nitrates and Nitrites in meat products

Nitrates and nitrites have been traditionally used as curing agents in the production of cured meat products. 
Beneficial effects of the addition of nitrates and nitrites to meat products are the improvement of quality characteristics as well as the microbiological safety. 
The nitrates and nitrites are mainly responsible for the development of the distinct flavor, the stability of the red color, as well as the protection against lipid oxidation in cured meat products. 
The nitrites show important bacteriostatic and bacteriocidal activity against several spoilage bacteria as well as foodborne pathogens found in meat products. 
The nitrites prevent the growth and toxin production by Clostridium botulinum. 
According to Commission Regulation (EU) No. 1129/2011, nitrates (sodium nitrate, E251; potassium nitrate, E252) and nitrites (potassium nitrite, E249; sodium nitrite, E250) are listed as permitted food additives. 
Nitrates are relatively non-toxic, but nitrites, and nitrites metabolic compounds such as nitric oxide and N-nitroso compounds, have raised concern over potential adverse health effects. 
Recently, the International Agency for Research on Cancer (IARC) concluded that ingested nitrates or nitrites are probable carcinogen to humans under conditions favoring the endogenous nitrosation. 
Legal limits for the addition of nitrates and nitrites have been set by several countries and EU [Commission Regulation (EU) No. 601/2014]. 
Several data from recent reviews conducted in several countries on the levels of nitrates and nitrites in cured meat products were summarized. 
In recent reviews, the residual levels of nitrites in cured meat samples have been constantly reduced and are in accordance with the legal limits set by most countries.

Sodium benzoate and sodium nitrite as corrosion‐inhibitors in ethylene glycol anti‐freeze solutions.

The addition of 1·5% sodium benzoate and 0·1% sodium nitrite to a 20% ethylene glycol anti‐freeze solution effectively prevents corrosion of cast iron and soldered joints in conditions of intermittent heating. 
In the absence of benzoate, sodium nitrite protects cast iron but increases the attack on soldered joints in glycol solutions, the intensity of attack increasing considerably over the range 0·1 to 1·5% sodium nitrite.

A short initial period of heating is necessary to ensure complete protection of cast iron in 20% glycol solution containing 1·5% sodium benzoate + 0·1% sodium nitrite. 
At room temperature without initial heating, 0·3% sodium nitrite is required to protect machined cast iron in 20% glycol solution containing 1·0 or 1·5% sodium benzoate; with 30% glycol and 1·0 or 1·5% sodium benzoate, 0·1% nitrite is sufficient. 
With ‘as‐cast’ surfaces higher concentrations of sodium nitrite are required to prevent rusting.

Corrosion inhibitors studies were carried out on carbon steel rebar samples under different pH conditions and in the presence and absence of chloride ions in solution. 
A known amount of sodium nitrite was added asan inhibitor and the mechanism of inhibition was studied by tracking both the thermodynamic and kinetic properties of the system. 
The studies indicate that Inhibition efficiency decreases with increase of temperature, and there is a competition between the corrosion and passivation reactions, and the resulting open-circuit potential depends on the relative strength of the corroding and passivating environments. 
The corrosion rate depends to a great extent on the pH of the solution. 
Nitrite ions act asanodic inhibitors by increasing the rate of formation of a barrier oxide film. 
The protective action of the nitriteions seems to be more pronounced in highly corroding environment. 
This is due to the mechanism of inhibition,which uses the product of the unwanted corrosion reaction and converts it into a favorable passivating one. 
For a given amount of chloride, a minimum threshold concentration of nitrite is essential for protecting the steel

Inhibition of Steel Corrosion by Sodium Nitrite in Water
Morris Cohen1
The Electrochemical Society
Journal of The Electrochemical Society, Volume 93, Number 1
Citation Morris Cohen 1948 J. Electrochem. Soc. 93 26

A study has been made of the effect of sodium nitrite on the corrosion of steel in water. 
The test methods included total and alternate immersion, a recirculation apparatus and potential measurements. 
The concentration of sodium nitrite required to inhibit steel corrosion depends on the conditions of motion and temperature. 
The inhibiting effect of sodium nitrite can be interpreted by solution potential measurements. 
The mechanism of inhibition is probably the formation of a protective oxide coating.

Sodium nitrite as a corrosion inhibitor of copper in simulated cooling water
The corrosion inhibition behavior of sodium nitrite (NaNO2) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO2 interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. 
Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. 
Sodium nitrite’s adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. 
Physiosorption mode was involved in the corrosion protection. 
Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. 
The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. 
The maximum inhibition was achieved with 2000 ppm of NaNO2. With this concentration, inhibition efficiency of up to 61.8% was achievable.

sodium nitrite
NaNO2    ChEBI
Natrium nitrit Deutsch    
Nitrite de sodium Français    
Nitrito sodico Español

[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2020]
[CITE: 21CFR172.175]


Subpart B - Food Preservatives

Sec. 172.175 Sodium nitrite.
The food additive sodium nitrite may be safely used in or on specified foods in accordance with the following prescribed conditions:

(a) It is used or intended for use as follows:

(1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite does not exceed 10 parts per million (0.001 percent) in the finished product.

(2) As a preservative and color fixative, with or without sodium nitrate, in smoked, cured sablefish, smoked, cured salmon, and smoked, cured shad so that the level of sodium nitrite does not exceed 200 parts per million and the level of sodium nitrate does not exceed 500 parts per million in the finished product.

(3) As a preservative and color fixative, with sodium nitrate, in meat-curing preparations for the home curing of meat and meat products (including poultry and wild game), with directions for use which limit the amount of sodium nitrite to not more than 200 parts per million in the finished meat product, and the amount of sodium nitrate to not more than 500 parts per million in the finished meat product.

(b) To assure safe use of the additive, in addition to the other information required by the Act:

(1) The label of the additive or of a mixture containing the additive shall bear:

(i) The name of the additive.

(ii) A statement of the concentration of the additive in any mixture.

(2) If in a retail package intended for household use, the label and labeling of the additive, or of a mixture containing the additive, shall bear adequate directions for use to provide a final food product which complies with the limitations prescribed in paragraph (a) of this section.

(3) If in a retail package intended for household use, the label of the additive, or of a mixture containing the additive, shall bear the statement "Keep out of the reach of children".


What is sodium nitrite? Sodium nitrite is a salt and an antioxidant that is used to cure meats like ham, bacon and hot dogs. 
Nitrite serves a vital public health function: it blocks the growth of botulism-causing bacteria and prevents spoilage. 
Nitrite also gives cured meats their characteristic color and flavor. 
In addition,United States Department of Agriculture (USDA)-sponsored research indicates that nitrite can help prevent the growth of Listeria monocytogenes, an environmental bacterium that can cause illness in some at-risk populations. 
Isn’t botulism one of those old diseases that aren’t really a problem anymore? 

Botulism is rare today because processing methods and preservatives like sodium nitrite are used to protect consumers. 
In fact, since sodium nitrite was approved for use in cured meats in 1925, no cases of botulism have been associated with commercially prepared cured meats. Sodium nitrite provides a food safety benefit to consumers. 
Are ‘nitrates’ used in curing meats? Decades ago, sodium nitrate - a “chemical cousin” of nitrite — was also used as a curing ingredient. 
Sodium nitrate, even though still permitted as an ingredient, is rarely used to cure meat and only in some certain specialty meat products. 

Are cured meats the major source of nitrite? 
Less than five percent of daily nitrite intake comes from cured meats. 
Nearly 93 percent of nitrite comes from leafy vegetables, tubers and our own saliva. 
Vegetables contain nitrate, which is converted to nitrite when it comes into contact with saliva in the mouth. 
In fact, the amount of nitrate in some vegetables can be very high. 
Spinach, for example, may contain 500 to 1900 parts per million (ppm) of nitrate; radishes may contain 1500 to 1800 ppm and lettuce may contain 600 to 1700 ppm. 
The nitrate to nitrite conversion process from eating vegetables makes up 85 percent of the average human dietary nitrite intake. 
By contrast, the amount of nitrite allowed by USDA to be added to cured meats is miniscule at no more than 156 ppm. 
In most cases, the amount added is 120 ppm or less and after processing the amount remaining in the final product is typically 10 ppm or less. 
This amount is approximately one-fifth the level of 25 years ago. There is another source of nitrite in the body. 
Called the “Molecule of the Year” by Science Magazine in 1992, nitric oxide is an amazing chemical that the body uses to control blood pressure, kill tumor cells and heal wounds. 
When nitrite oxide is done with its work, its byproduct is nitrite. 
So clearly, nitrite is something that is made by the body as part of its normal, healthy processes. 

Can cured meats be produced without sodium nitrite? 
Cured meats by their legal USDA definition must include sodium nitrite. 
Sodium nitrite is the very ingredient that gives a product like ham its color and taste. 

Its shelf-life also would be shortened substantially. 
Some uncured products are available today that use ingredients like beet or celery juice or natural sea salt to deliver a color and flavor similar to traditional cured meats. Beets, celery and sea salt all contain nitrate. 
When the nitrate in celery, beets and sea salt, and other nitrate-containing vegetables, is exposed to certain types of bacteria in the product, nitrate is converted to nitrite, which results in product characteristics similar to traditionally cured meat products. 
The amount of nitrite consumed from these types of products versus traditionally cured meat products is virtually the same. 
I heard some people say that nitrite causes cancer.  

Is sodium nitrite safe? Numerous scientific panels have evaluated sodium nitrite safety and the conclusions have essentially been the same: nitrite is not only safe, it is an essential public health tool because it has a proven track record of preventing botulism. 
Specifically, the National Toxicology Program, an agency within the U.S. Department of Health & Human Services and a leading authority on the toxicological safety of chemicals, conducted a multi-year study to evaluate its safety. 
The study, approved by a panel of experts in May 2000, found that nitrite was safe at the levels used. 
A panel convened by the California Office of Environmental Health Hazard Assessment in June 2000 also determined that nitrite at the levels used did not pose any risk to developing fetuses. 

Is it true that nitrite actually may have health benefits? 
Evidence is mounting that nitrite actually does have numerous health benefits. 
Studies have shown that nitrite is part of the body’s healthy nitrogen cycle. 
The body converts nitrate to nitrite to regulate blood pressure, promote wound healing, destroy pathogens in the gut and even to prevent preeclampsia during pregnancy. 
Scientists at the National Institutes of Health (NIH) over the last several years have announced a number of studies that document the health benefits of nitrite. 

Sodium nitrite, with chemical formula NaNO2, and molar mass of 69.00 g/mol is used as a color fixative and preservative in meats and fish. 
When pure, it is a white to slight yellowish crystalline powder. It is very soluble in water and is hygroscopic. 
It is also slowly oxidized by oxygen in the air to sodium nitrate, NaNO3. 
The compound is a strong reducing agent.
It is also used in manufacturing diazo dyes, nitroso compounds, and other organic compounds; in dyeing and printing textile fabrics and bleaching fibers; in photography; as a laboratory reagent and a corrosion inhibitor; in metal coatings for phosphatizing and detinning; and in the manufacture of rubber chemicals. Sodium nitrite also has been used in human and veterinary medicine as a vasodilator, a bronchodilator, an intestinal relaxant or a laxative, and an antidote for cyanide poisoning.

231-555-9 [EINECS]
7632-00-0 [RN]
Azotyn sodowy [Polish]
Dusitan sodny [Czech]
MFCD00011118 [MDL number]
NaNO2 [Formula]
Natrium nitrit [German]
Natriumnitrit [German] [ACD/IUPAC Name]
Nitrite de sodium [French] [ACD/IUPAC Name]
Nitrito sodico [Spanish]
Nitrous acid sodium salt
Sodium nitrate(III)
Sodium nitrite [ACD/IUPAC Name] [Wiki]
Sodium nitrite [UN1500] [Oxidizer]
32863-15-3 [RN]
56227-20-4 [RN]
68378-96-1 [RN]
82497-43-6 [RN]
82998-40-1 [RN]
Azotyn sodowy
Azotyn sodowy [Polish]
diazoting salts
Dusitan sodny
Dusitan sodny [Czech]
EINECS 231-555-9
Natrium nitrit
Natrium nitrit [German]
Nitrite de sodium [ACD/IUPAC Name]
Nitrite de sodium [French]
Nitrite sodium
Nitrite, Sodium
Nitrito sodico
Nitrito sodico [Spanish]
Nitrous Acid Soda
Nitrous acid, sodium salt
Sodium nitrite (NaNO2 )
Sodium nitrite (USP)
Sodium nitrite ACS grade
Sodium nitrite, Trace metals grade
亚硝酸钠 [Chinese]

azotan(III) sodu (pl)
azotit de sodiu (ro)
azotyn sodu (pl)
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dusitan sodný (sk)
Naatriumnitrit (et)
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natrio nitritas (lt)
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natriumnitrit (da)
Natriumnitrit (de)
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nitrito de sodio (es)
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sodio nitrito (it)
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