SODIUM NITRATE

CAS Number: 7631-99-4
 Synonyms: E251; Nitric acid sodium salt; Chile saltpeter; Peru saltpeter; Soda niter; Sodium saltpeter; Cubic niter; Nitratine (mineral form)
Physical Properties:
Appearance: White to colorless crystalline powder or granules (sometimes slightly grayish or yellowish if impure).
Solubility: Very soluble in water (approx. 88 g/100 mL at 20°C; 180 g/100 mL at 80°C); slightly soluble in ethanol (negligible); insoluble in concentrated nitric acid (passivates).
Molecular weight: 84.99 g/mol.
Melting point: 308°C (decomposes at ~380°C releasing oxygen and nitrogen oxides).
Density: 2.26 g/cm³ (crystalline).
pH (5% solution): 6.0–7.5 (neutral to slightly alkaline).
Hygroscopicity: Slightly hygroscopic (absorbs less moisture than sodium nitrite; does not deliquesce easily).
Oxidizing properties: Strong oxidizer when molten; supports combustion of organic matter; forms explosive mixtures with reducing agents (e.g., sulfur, charcoal, aluminum powder).
Applications:
Cured meat and fish (E251): Dry-cured hams (Serrano, Prosciutto, Parma), country ham, dry sausages (salami, pepperoni, summer sausage), dry-cured bacon, corned beef (alternate or in combination with nitrite), canned meats, and some smoked fish. Also used in brine for pickled meats.
Cheese: Surface-ripened cheeses (Emmental, Gruyère, Gouda, Edam) and some processed cheeses (E251 prevents late blowing by Clostridium tyrobutyricum).
Fertilizer (historical, still used): High-nitrogen, water-soluble fertilizer for crops (especially leafy greens, citrus, and tobacco). Chile saltpeter was historically the primary source before synthetic ammonia (Haber process).
Industrial: Heat transfer salt for molten salt storage (sodium nitrite + sodium nitrate + potassium nitrate eutectics), oxidizer in pyrotechnics (rocket propellants, explosives, fireworks), metal treatment (nitriding baths), glass manufacturing (oxidizing agent, decolorizer), laboratory reagent.
Medical/Wastewater: Oxygen source in denitrification studies; component of some dialysis solutions (very low levels).
Corrosion inhibitor: In cooling systems and oilfield operations.
Description:
 Sodium nitrate (E251) is an inorganic nitrate salt that functions as a slow-release source of nitrite in food systems. Unlike nitrites (E249/E250), nitrates themselves are relatively inert and have weak direct antimicrobial activity. However, nitrate-reducing bacteria (e.g., Micrococcus, Staphylococcus carnosus, Kocuria varians, Lactobacillus sakei) present in dry-cured meats and certain cheeses reduce nitrate to nitrite via the enzyme nitrate reductase. The generated nitrite then provides the same cured color, flavor, and Clostridium botulinum inhibition as directly added nitrite. This "indirect" mechanism is why nitrates are used almost exclusively in long-ripened, fermented, or dry-cured products (aging >3 weeks) where sufficient time and microbial activity allow for nitrate → nitrite conversion. In products with short curing times or high-heat processing (e.g., hot dogs, commercial hams), sodium nitrate is ineffective, and nitrites (E249/E250) must be used directly. In dry-cured hams (e.g., Parma ham, aged 12-24 months), sodium nitrate is added early; over weeks to months, bacteria gradually convert nitrate to nitrite, which then forms nitrosomyoglobin and inhibits pathogens. This slow release avoids the need for repeated nitrite additions and ensures residual nitrite remains low at the time of consumption. The ADI for nitrate (expressed as sodium nitrate) is 0–3.7 mg/kg bw/day (JECFA). Toxic concerns: Nitrates themselves have low acute toxicity (oral LD₅₀ in rats ~ 3000 mg/kg). However, in the human body, about 5-10% of ingested nitrate is reduced to nitrite by oral bacteria (on the tongue dorsum). The resulting nitrite can then react with amines to form N-nitrosamines in the acidic stomach. Additionally, high nitrate intake has been associated with methemoglobinemia in infants (especially <6 months old, "blue baby syndrome") when nitrates contaminate drinking water or infant formula prepared with high-nitrate well water. This occurs because infant gastric pH is higher (less acidic), allowing bacteria to colonize the upper gastrointestinal tract excessively, converting more nitrate to nitrite, which then oxidizes fetal hemoglobin (more sensitive to oxidation) to methemoglobin. For this reason, the EU limits nitrate in infant foods and drinking water (50 mg/L). In adults, nitrate consumption from vegetables (e.g., spinach, arugula, beets, lettuce, celery) is far higher than from cured meats. For example, one serving of spinach (100g) contains up to 2000 mg nitrate, while a serving of dry-cured ham contains 10-50 mg nitrate. Paradoxically, dietary nitrate from vegetables has been associated with cardiovascular benefits (improved blood flow, reduced blood pressure) via conversion to nitric oxide (NO) through the enterosalivary nitrate-nitrite-NO pathway. This is the basis for beetroot juice supplementation in athletes. Therefore, nitrate's reputation as harmful is context-dependent: in infants or with reduced vitamin C intake, nitrate poses risks; in adults with adequate antioxidants, nitrate may be beneficial. In cheese manufacturing, sodium nitrate (E251) is added to milk for Emmental and Gouda to prevent "late blowing" – a defect caused by Clostridium tyrobutyricum spores that survive pasteurization. The nitrate is reduced to nitrite by starter bacteria, inhibiting Clostridia and preserving the cheese's characteristic closed texture. Without nitrate, late blowing causes large gas holes, off-flavors, and swelling of the cheese blocks. No alternative preserves the cheese as effectively while being compatible with traditional production. In industrial applications, sodium nitrate is the key component of molten salt mixtures (e.g., "Solar Salt" – 60% NaNO₃ + 40% KNO₃) used in concentrated solar thermal plants. The salt melts at 220°C and remains liquid up to 600°C, storing thermal energy for electricity generation after sunset. The global demand for sodium nitrate in industrial uses now exceeds its food use. However, in many countries (e.g., Japan, Australia, New Zealand, and the EU), E251 is increasingly being replaced by potassium nitrate (E252) for some applications because potassium nitrate provides potassium (a beneficial nutrient) rather than sodium, aligning with health guidelines to lower sodium intake.

SAFETY INFORMATION ABOUT SODIUM NITRATE

First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product