E537 - ferrous hexacyanomanganate

At a glance

• What it is: a complex salt containing iron, manganese, and cyanide ligands (a class of “cyanometallates”).
• Typical role: reported historically as an anti-caking agent to help table salt pour freely.
• Where it shows up: modern EU and U.S. foods seldom list it; other anti-caking agents are used instead.
• Regulatory status: not on the EU’s Union list of authorised food additives and not listed by the U.S. FDA as an approved food additive.
• Safety notes: no established food-use specifications or acceptable daily intake specifically for E537; assessments available for related ferrocyanides do not automatically apply.

Why is ferrous hexacyanomanganate added to food?

Anti-caking agents keep powders such as table salt free-flowing by preventing crystals from sticking together. For example, the EU has assessed and authorised ferrocyanide anti-caking agents (E 535–E 538) for use in salt because they coat crystal surfaces to limit clumping.¹ Ferrous hexacyanomanganate (E537) has been described for a similar purpose, though it does not appear on the EU list of authorised additives.²

What foods contain ferrous hexacyanomanganate?

Mentions of E537 are most often linked to table salt and other dry, free-flowing foods. In current practice, you are unlikely to find it on EU labels because it is not listed in the Union specifications for food additives.² It is also not included on the U.S. Food and Drug Administration’s Food Additive Status List.³

What can replace ferrous hexacyanomanganate?

Manufacturers commonly choose other anti-caking agents with established approvals and specifications, such as:

• silicon dioxide
• calcium silicate
• Tricalcium phosphate (tricalcium phosphate)
• Calcium carbonate (calcium carbonate)
• The authorised ferrocyanides in some markets (e.g., sodium, potassium, or calcium ferrocyanide)

How is ferrous hexacyanomanganate made?

Because E537 is not included in the EU specifications for food additives, no food-grade manufacturing specification is published there.² In general terms, cyanometallate salts are produced by reacting metal ions with hexacyanometallate complexes to form stable coordination compounds, but process details for E537 as a food additive are not provided in EU specifications.²

Is ferrous hexacyanomanganate safe to eat?

There is no established EU specification or authorisation for E537, so its use in food is not allowed in the EU and no acceptable daily intake (ADI) specific to this compound has been set there.⁴ By contrast, the EFSA Panel re-evaluated the ferrocyanides (E 535–E 538) and concluded they are safe at permitted levels when used as anti-caking agents in salt; that conclusion does not automatically extend to E537 because it is a different compound.¹ In the United States, E537 does not appear on FDA’s Food Additive Status List, indicating it is not an approved food additive.³

Does ferrous hexacyanomanganate have any benefits?

It does not provide nutritional benefits. Its intended role is purely technological—helping powders like salt stay free-flowing—an effect that is readily achieved with several authorised anti-caking agents.

Who should avoid ferrous hexacyanomanganate?

• Consumers who prefer to avoid anti-caking agents can choose salts labeled “additive-free” or those using agents they are comfortable with.
• If you are following advice to limit sodium or processed foods, selecting minimally processed options remains a straightforward approach.

Myths & facts

• Myth: “If it has an E-number, it must be synthetic or unsafe.” Fact: An E-number simply means an additive has been evaluated for specific uses in the EU; many E-numbered additives are identical to substances found in nature (for example, ascorbic acid).⁵
• Myth: “You’ll find E537 on EU food labels.” Fact: Ferrous hexacyanomanganate is not on the EU’s Union list of authorised food additives, so it should not appear on compliant EU labels.²

ferrous hexacyanomanganate in branded foods

Major EU and U.S. brands generally use authorised anti-caking agents with published specifications (e.g., silicon dioxide or calcium silicate). Given that E537 is not on the EU Union list and is not listed by FDA as an approved food additive, it is unlikely to appear on current mainstream products in those markets.²³

References

At a glance

• What it is: a complex salt containing iron, manganese, and cyanide ligands (a class of “cyanometallates”).
• Typical role: reported historically as an anti-caking agent to help table salt pour freely.
• Where it shows up: modern EU and U.S. foods seldom list it; other anti-caking agents are used instead.
• Regulatory status: not on the EU’s Union list of authorised food additives and not listed by the U.S. FDA as an approved food additive.
• Safety notes: no established food-use specifications or acceptable daily intake specifically for E537; assessments available for related ferrocyanides do not automatically apply.

Why is ferrous hexacyanomanganate added to food?

Anti-caking agents keep powders such as table salt free-flowing by preventing crystals from sticking together. For example, the EU has assessed and authorised ferrocyanide anti-caking agents (E 535–E 538) for use in salt because they coat crystal surfaces to limit clumping.¹ Ferrous hexacyanomanganate (E537) has been described for a similar purpose, though it does not appear on the EU list of authorised additives.²

What foods contain ferrous hexacyanomanganate?

Mentions of E537 are most often linked to table salt and other dry, free-flowing foods. In current practice, you are unlikely to find it on EU labels because it is not listed in the Union specifications for food additives.² It is also not included on the U.S. Food and Drug Administration’s Food Additive Status List.³

What can replace ferrous hexacyanomanganate?

Manufacturers commonly choose other anti-caking agents with established approvals and specifications, such as:

• silicon dioxide
• calcium silicate
• Tricalcium phosphate (tricalcium phosphate)
• Calcium carbonate (calcium carbonate)
• The authorised ferrocyanides in some markets (e.g., sodium, potassium, or calcium ferrocyanide)

How is ferrous hexacyanomanganate made?

Because E537 is not included in the EU specifications for food additives, no food-grade manufacturing specification is published there.² In general terms, cyanometallate salts are produced by reacting metal ions with hexacyanometallate complexes to form stable coordination compounds, but process details for E537 as a food additive are not provided in EU specifications.²

Is ferrous hexacyanomanganate safe to eat?

There is no established EU specification or authorisation for E537, so its use in food is not allowed in the EU and no acceptable daily intake (ADI) specific to this compound has been set there.⁴ By contrast, the EFSA Panel re-evaluated the ferrocyanides (E 535–E 538) and concluded they are safe at permitted levels when used as anti-caking agents in salt; that conclusion does not automatically extend to E537 because it is a different compound.¹ In the United States, E537 does not appear on FDA’s Food Additive Status List, indicating it is not an approved food additive.³

Does ferrous hexacyanomanganate have any benefits?

It does not provide nutritional benefits. Its intended role is purely technological—helping powders like salt stay free-flowing—an effect that is readily achieved with several authorised anti-caking agents.

Who should avoid ferrous hexacyanomanganate?

• Consumers who prefer to avoid anti-caking agents can choose salts labeled “additive-free” or those using agents they are comfortable with.
• If you are following advice to limit sodium or processed foods, selecting minimally processed options remains a straightforward approach.

Myths & facts

• Myth: “If it has an E-number, it must be synthetic or unsafe.” Fact: An E-number simply means an additive has been evaluated for specific uses in the EU; many E-numbered additives are identical to substances found in nature (for example, ascorbic acid).⁵
• Myth: “You’ll find E537 on EU food labels.” Fact: Ferrous hexacyanomanganate is not on the EU’s Union list of authorised food additives, so it should not appear on compliant EU labels.²

ferrous hexacyanomanganate in branded foods

Major EU and U.S. brands generally use authorised anti-caking agents with published specifications (e.g., silicon dioxide or calcium silicate). Given that E537 is not on the EU Union list and is not listed by FDA as an approved food additive, it is unlikely to appear on current mainstream products in those markets.²³

References

Footnotes

1. Re-evaluation of ferrocyanides (E 535–538) as food additives — EFSA Journal (2018). https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2018.5364 ↩ ↩² ↩³ ↩⁴

2. Commission Regulation (EU) No 231/2012 laying down specifications for food additives listed in Annex II to Regulation (EC) No 1333/2008. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

3. Food Additive Status List — U.S. FDA. https://www.fda.gov/food/food-additives-petitions/food-additive-status-list ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

4. EU Food Additives Database (authorised additives and uses) — European Commission. https://webgate.ec.europa.eu/foods_system/main/?sector=FADE537 — ferrous hexacyanomanganate — is a coordination compound that has been cited historically as an anti-caking aid, particularly for salt. Today it is rarely seen on labels and is not listed as an authorised additive in either the European Union or the United States. ↩ ↩²

5. Food additives: How the EU works with E-numbers — European Commission. https://food.ec.europa.eu/safety/food-improvement-agents/food-additives_en ↩ ↩²