E252 - Potassium nitrate

At a glance

• What it is: A mineral salt (also called saltpeter) used as a preservative.
• E-number: E252; common label names include “potassium nitrate” or “E252”.
• What it does: Supports safe curing in some meats and cheeses; helps maintain color and control spoilage microbes.
• Where it’s found: Traditional dry-cured meats (e.g., salami, country ham) and some hard, cooked cheeses.
• Dietary notes: Not derived from animals; suitable for vegetarian and vegan diets.
• Storage and cooking: Stable in dry form; its role in curing depends on time, microflora, and recipe.

Why is Potassium nitrate added to food?

Potassium nitrate is used in curing because it slowly provides nitrite during long ripening, which helps keep cured meats safe and develop a stable pink color. In the United States, it is an approved curing ingredient for certain meat and poultry products; in the European Union, it is an authorized preservative in specific meat and cheese categories.¹² The protective effect against dangerous bacteria in cured meats is mainly due to nitrite formed during curing, which inhibits growth and toxin formation by Clostridium botulinum.³

What foods contain Potassium nitrate?

You are most likely to see potassium nitrate in:

• Traditional dry-cured meats that age for a long time (for example, some salamis and country-style hams)
• A few hard, cooked cheeses where it helps control defects during ripening

In the EU, its use is limited to certain categories defined in the additives regulation; in the U.S., it appears on the list of safe and suitable ingredients for meat and poultry.²¹ On labels, look for “potassium nitrate,” “E252” (in the EU/UK), or for related curing agents such as sodium nitrate and sodium nitrite.

What can replace Potassium nitrate?

• For long, traditional cures: sodium nitrate (E251) serves a similar role as a slow source of nitrite.
• For shorter cures: Direct nitrite sources like sodium nitrite or potassium nitrite are often used by processors.
• For non-cured foods: Other preservatives may be chosen, such as sorbic acid, potassium sorbate, or sodium benzoate, depending on the product and regulations.

Processors also rely on refrigeration, salt level, acidity, and drying to keep foods safe and stable.

How is Potassium nitrate made?

Commercial potassium nitrate is typically produced by neutralizing nitric acid with a potassium source (such as potassium chloride or potassium hydroxide), followed by purification and crystallization. It also occurs naturally in some mineral deposits. Food-grade material must meet purity specifications for additives.⁴

Is Potassium nitrate safe to eat?

Regulators set strict purity, use-cases, and maximum levels. The European Food Safety Authority (EFSA) set an acceptable daily intake (ADI) for nitrate of 3.7 mg per kilogram of body weight per day, expressed as nitrate ion.⁵ EFSA noted that most people’s nitrate exposure comes from vegetables and drinking water, not food additives, although total intake can vary with diet.⁵ In both the EU and U.S., allowed uses and levels in cured meats and certain cheeses are controlled to manage risks, including the possible formation of nitrosamines; processors use good manufacturing practices and added antioxidants to reduce these risks.²⁶

Does Potassium nitrate have any benefits?

• Food safety and quality in cured meats: Through its conversion to nitrite during curing, it helps prevent botulism and supports cured color and flavor in traditional, long-aged products.³
• Cheese stability: In some cooked, hard cheeses, controlled use can help prevent spoilage defects during ripening as permitted by EU rules.²

Who should avoid Potassium nitrate?

• Infants: Very young infants are more sensitive to nitrate/nitrite-related methemoglobinemia. While the main concern is high nitrate in water and certain vegetables, caution around total nitrate intake is prudent for this age group.⁵
• People advised to limit nitrate/nitrite: Those under medical advice to restrict these compounds should read labels and choose products accordingly. If in doubt, consult a healthcare professional.

Myths & facts

• “Nitrates are only synthetic.” Fact: Nitrates occur naturally, and vegetables are a major source of dietary nitrate for most people.⁵
• “Potassium nitrate cures meat by itself.” Fact: Its curing role comes from conversion to nitrite over time; nitrite is the compound that suppresses C. botulinum and sets cured color.³
• “Regulators don’t manage nitrosamines.” Fact: Curing practices are tightly regulated, and antioxidants like ascorbic acid, sodium ascorbate, or sodium erythorbate are required in certain products (e.g., pumped bacon) to reduce nitrosamine formation.⁶

Potassium nitrate in branded foods

You may find potassium nitrate listed on traditional dry-cured meats and some hard, cooked cheeses. Labels may use “potassium nitrate,” “E252” (EU/UK), or a related curing agent such as sodium nitrate or sodium nitrite. Availability and usage depend on local regulations and the specific recipe.

References

Footnotes

1. Safe and Suitable Ingredients Used in the Production of Meat, Poultry, and Egg Products (FSIS Directive 7120.1) — USDA FSIS. https://www.fsis.usda.gov/policy/fsis-directives/7120.1 ↩ ↩²

2. Regulation (EC) No 1333/2008 on food additives (and Annex II use categories) — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32008R1333 ↩ ↩² ↩³ ↩⁴

3. Re-evaluation of nitrites (E 249–250) as food additives: antimicrobial function in cured meats — EFSA. https://www.efsa.europa.eu/en/efsajournal/pub/4786 ↩ ↩² ↩³

4. Potassium nitrate — PubChem (NIH/NLM). https://pubchem.ncbi.nlm.nih.gov/compound/Potassium-nitrate ↩

5. Re-evaluation of sodium nitrate (E 251) and potassium nitrate (E 252) as food additives — EFSA. https://www.efsa.europa.eu/en/efsajournal/pub/4787 ↩ ↩² ↩³ ↩⁴

6. Use of curing agents; restrictions (requires ascorbate/erythorbate in certain bacon) — 9 CFR 424.21(c), eCFR. https://www.ecfr.gov/current/title-9/chapter-III/subchapter-E/part-424/section-424.21 ↩ ↩²