E539 - sodium thiosulfate
Synonyms: E539sodium thiosulfate
Origin:
Products: Found in 20 products
Sodium thiosulfate (E539) is a food additive used in small amounts to protect foods from unwanted chemical changes. It acts as an antioxidant and a sequestrant, meaning it can slow oxidation and bind reactive trace metals. You will most often see it on labels as “sodium thiosulfate” or “E539.”
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At a glance
- E-number: E539; names: sodium thiosulfate, sodium thiosulphate
- Role: antioxidant and sequestrant that helps control oxidation and bind metal ions
- Appearance: colorless crystals, usually as a pentahydrate; dissolves well in water
- Where allowed, it is used in very small amounts for specific purposes
- Label reading: appears as “sodium thiosulfate” or “E539”
Why is sodium thiosulfate added to food?
Food makers use sodium thiosulfate because it helps keep flavor, color, and freshness. As an antioxidant and sequestrant, it can mop up reactive molecules and trace metals that drive oxidation, which in turn helps slow staling, off-flavors, and discoloration.1 In the EU, it is listed and defined as a food additive with these functional classes, so its use is limited to technological needs and good manufacturing practice.2
What foods contain sodium thiosulfate?
Use depends on local rules. In the European Union, sodium thiosulfate is on the Union list of approved food additives and may be used only in the food categories and at the levels set by law.2 If present, you will see it in the ingredients list as “sodium thiosulfate” or “E539.”
What can replace sodium thiosulfate?
Depending on the job it needs to do, formulators may choose:
- Other antioxidants, such as ascorbic acid
- Acidulants and chelators that bind metals, such as citric acid
- Sulfite-based antioxidants where permitted, such as sodium metabisulphite or sulphur dioxide
- Chelating agents like calcium disodium EDTA
- For salt flow and stability needs, anti-caking agents such as sodium ferrocyanide, potassium ferrocyanide, or calcium ferrocyanide
Each alternative has its own flavor impact, legal limits, and labeling rules.
How is sodium thiosulfate made?
Commercial sodium thiosulfate is commonly produced by reacting sodium sulfite with elemental sulfur in water, followed by crystallization—often as the pentahydrate form (Na2S2O3·5H2O).3 Food-grade material must also meet identity and purity specifications set out in EU law.1
Is sodium thiosulfate safe to eat?
Within the European Union, sodium thiosulfate is an authorized food additive. That means it has specifications and may be used only for technological purposes under the conditions laid down in the additives regulation.2 The additive must meet strict purity criteria before it can be sold for food use.1
Does sodium thiosulfate have any benefits?
Its benefits are technological rather than nutritional. By controlling oxidation and binding reactive metals, sodium thiosulfate helps maintain taste, color, and shelf stability in foods where its use is permitted.1
Who should avoid sodium thiosulfate?
- People who must carefully manage total sodium intake should review overall diet and check labels, as advised by their healthcare professional.
- Anyone with a diagnosed sensitivity and specific guidance from a clinician about sulfur-containing additives should discuss suitable choices with them.
Myths & facts
- Myth: “It’s a photographic chemical, so it can’t be food-grade.” Fact: Food-use sodium thiosulfate must meet official food purity specifications; industrial grades are not allowed in foods.1
- Myth: “An E-number means it’s unsafe.” Fact: An E-number means the additive is authorized for use in the EU with defined purposes and conditions set in law.2
sodium thiosulfate in branded foods
Not all countries allow the same uses, and many products do not need this additive. When it is used, you’ll see it in the ingredient list as “sodium thiosulfate” or “E539.” If you are curious about a specific product, check the label or the brand’s website.
References
Footnotes
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Commission Regulation (EU) No 231/2012 laying down specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008 — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0231 ↩ ↩2 ↩3 ↩4 ↩5
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Regulation (EC) No 1333/2008 on food additives (Union list and conditions of use) — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32008R1333 ↩ ↩2 ↩3 ↩4
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Sodium Thiosulfate — PubChem (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-thiosulfate ↩
Popular Questions
What is sodium thiosulfate used for?
As a food additive (E539), it functions as an antioxidant and sequestrant, binding trace metals and helping prevent oxidation; it’s also used to neutralize residual chlorine in processing water.
How much sodium thiosulfate to neutralize chlorine?
About 7 parts of sodium thiosulfate pentahydrate (Na2S2O3·5H2O) are needed per 1 part of chlorine (as Cl2) by weight—for example, ~7 mg/L thiosulfate per 1 mg/L free chlorine; in practice, a small excess is often used.
Is gold sodium thiosulfate in makeup?
Gold sodium thiosulfate is a different compound from food additive E539 and isn’t typically used in cosmetics; check the ingredient list if you’re concerned about gold-containing ingredients.
How many elements are in sodium thiosulfate?
Anhydrous sodium thiosulfate (Na2S2O3) contains 3 elements (Na, S, O); the common pentahydrate (Na2S2O3·5H2O) includes 4 (adds H from the water of crystallization).
What does sodium thiosulfate do?
In foods it acts as an antioxidant and sequestrant, helping prevent oxidation and off-colors by binding metals, and it can dechlorinate processing water.
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