E579: Iron gluconate

What is E579?

E579 is ferrous gluconate, an iron salt of gluconic acid. It is a greenish-grey to yellowish powder that dissolves in water and contains iron in its ferrous (Fe2+) form.

Origin and production

Ferrous gluconate is produced by reacting gluconic acid, usually obtained by fermenting glucose, with an iron compound such as iron carbonate or iron powder. It does not involve animal materials.

Why is it used?

Its main food use is in ripe black olives that are darkened by oxidation: iron gluconate fixes and stabilises the uniform black colour during processing. As a result it is found in black pitted and whole olives, and in pizzas and salads that contain them; it can also serve as an iron source in supplements.

Vegan, vegetarian and halal

E579 is mineral and fermentation-derived and suitable for vegans and vegetarians. It raises no particular halal or kosher concerns.

Safety and regulation

Ferrous gluconate is authorised in the European Union only for olives darkened by oxidation, within set limits. EFSA re-evaluated ferrous gluconate and ferrous lactate in 2015 and did not identify a safety concern at that use.

Common in