E515I - Potassium sulphate

At a glance

• What it is: a potassium and sulphate salt (K2SO4), also called potassium sulfate/sulphate
• What it does: helps regulate acidity, stabilise formulations, and act as a processing aid
• Where it’s found: a range of processed foods; listed on labels as “potassium sulphate,” “potassium sulfate,” “E515,” or “E515i”
• Taste and texture: neutral taste; stable under heat
• Dietary notes: mineral salt, vegan-friendly, gluten‑free by nature
• Regulation: carries the E‑number E515i in the EU, with defined identity and purity specifications

Why is Potassium sulphate added to food?

Potassium sulphate is added because it is a simple, stable mineral salt that helps manage acidity and ionic balance in recipes. It can stabilise certain gels and mixes, act as a carrier for nutrients or flavours, and support processing without adding sodium. In the EU it is an authorised food additive with a defined E‑number (E515i) and official specifications, which confirm its identity and purity for food use.¹

What foods contain Potassium sulphate?

You may find potassium sulphate across different processed foods where a neutral, potassium‑based salt is needed—for example, in some beverages, dessert mixes, or specialised diet products. Actual permissions vary by country and product type, so the best way to know is to check the ingredient list for “potassium sulphate,” “potassium sulfate,” “E515,” or “E515i.” In the EU, its authorisation and purity specifications are set in law.¹

What can replace Potassium sulphate?

Possible substitutes depend on the job it is doing:

• For a similar mineral salt role: sodium sulphates, calcium sulphate, or magnesium sulphate may be options (mind taste, sodium content, and regulations).
• For acidity control: citric acid or phosphoric acid may be used, depending on the recipe and local rules.
• For processing needs: technologists may adjust the process or switch to other approved carriers or stabilisers.

How is Potassium sulphate made?

Food‑grade potassium sulphate is typically produced by neutralising sulphuric acid with a potassium base such as potassium carbonate or potassium hydroxide, followed by purification and crystallisation.² In the EU, it must meet identity and purity criteria (for example, limits for insoluble matter and certain impurities) set out in Commission Regulation (EU) No 231/2012.¹

Is Potassium sulphate safe to eat?

The European Food Safety Authority (EFSA) re‑evaluated sulphuric acid and sulphates, including potassium sulphate (E 515), and concluded there was no safety concern at the reported uses and use levels in foods.³ Like other sulphate salts, very high intakes can have a laxative effect, but the amounts used in foods are much lower than the levels linked to such effects.³

Does Potassium sulphate have any benefits?

Potassium is an essential mineral that supports normal nerve transmission, muscle function, and fluid balance.⁴ Potassium sulphate can contribute small amounts of potassium when used, although food additives are typically present at low levels and are not intended as nutrient supplements.⁴

Who should avoid Potassium sulphate?

• People who must limit potassium (for example, those with kidney disease or on certain medicines like potassium‑sparing diuretics or ACE inhibitors) should follow their healthcare provider’s advice about total potassium intake from all sources.⁴
• Anyone who notices digestive discomfort from sulphates should be aware that high doses can have a laxative effect; this is unlikely at typical food additive levels but can occur with large sulphate intakes (for example, from water).[^\2]

Myths & facts

• Myth: “Sulfates are the same as sulfites.” Fact: Sulphates (like E515i) are different from sulphites (such as sulphur dioxide), which are preservatives and a common allergen statement.
• Myth: “It makes food taste salty.” Fact: Potassium sulphate has a neutral taste and is used for function, not flavour.
• Myth: “It’s just fertiliser in food.” Fact: Food‑grade potassium sulphate must meet strict purity standards for use in foods.
• Myth: “It’s banned.” Fact: It is an authorised additive with specifications in the EU.

Potassium sulphate in branded foods

On labels, look for “potassium sulphate,” “potassium sulfate,” “E515,” or “E515i.” Placement is in the ingredient list, usually near other salts, acids, or stabilisers. If you are managing potassium intake, compare similar products and choose the one that fits your dietary plan.

References

Footnotes

1. Commission Regulation (EU) No 231/2012 — Specifications for food additives. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0231 ↩ ↩² ↩³

2. Potassium sulfate — PubChem (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Potassium-sulfate ↩

3. Re-evaluation of sulfuric acid (E 513), sodium sulfate (E 514), potassium sulfate (E 515) and calcium sulfate (E 516) as food additives — EFSA Journal. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2018.5369 ↩ ↩²

4. Potassium Fact Sheet for Health Professionals — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/ ↩ ↩² ↩³