E519 - Copper sulphate

At a glance

• What it is: A salt of copper and sulfate, most often used as the blue pentahydrate crystals (CuSO4·5H2O).
• What it does: Provides copper as a nutrient, and is used in winemaking to remove “reduced” sulfur smells.
• Where you’ll see it: On labels as “copper sulphate,” “cupric sulfate,” or “E519”; rare in everyday foods, more common in mineral premixes, supplements, and winery operations.
• Safety notes: Copper is essential in small amounts but can cause stomach upset at high intakes; regulators set strict purity criteria and maximum levels.

Why is Copper sulphate added to food?

Manufacturers use copper sulphate as a permitted source of copper when fortifying foods or making dietary supplements, because copper is an essential trace mineral for human health.¹ In wineries, it may be used as a processing aid to bind hydrogen sulfide and other sulfur compounds that cause “rotten egg” aromas; the European Union allows this practice with a strict limit on residual copper in the finished wine.²

It is also used upstream when producing certain green color additives, such as the copper complexes of chlorophylls and chlorophyllins, though those colors are separately regulated as E141.

What foods contain Copper sulphate?

• Fortified foods and dietary supplements may list copper sulphate as the mineral source, within the categories and forms authorized by the EU for copper addition.¹
• Wines treated with copper sulphate during cellar work can contain trace amounts of copper; in the EU, the residual copper in wine must not exceed 1.0 mg/L.²

Outside of these uses, you’re unlikely to see E519 commonly listed on everyday packaged foods.

What can replace Copper sulphate?

• For copper fortification: Other permitted copper salts (for example, gluconate or citrate forms) are often used as alternatives, depending on taste, solubility, and formulation needs.
• For winemaking sulfur issues: Non-additive techniques such as controlled aeration, racking, or managing fermentation can reduce sulfur off-odors.
• For green color: Makers typically use approved color additives like copper complexes of chlorophylls and chlorophyllins, rather than adding copper sulphate itself.

How is Copper sulphate made?

Industrial copper sulphate is typically produced by reacting copper metal, copper oxide, or copper hydroxide with sulfuric acid, then crystallizing the distinctive blue pentahydrate (CuSO4·5H2O).³ When used as E519 in the EU, it must meet official identity and purity criteria set for food additives.⁴

Is Copper sulphate safe to eat?

Copper is an essential nutrient, and small amounts from food and allowed additives are part of normal intake. However, too much copper at once can cause nausea, abdominal pain, and diarrhea. The U.S. National Institutes of Health lists a tolerable upper intake level (UL) of 10 mg/day for adults from all sources combined.⁵ To help ensure safe use, the EU sets strict specifications for E519 purity,⁴ and in winemaking specifically, caps residual copper at 1.0 mg/L in finished wine.²

Does Copper sulphate have any benefits?

Yes—when it supplies copper, it helps meet the body’s need for this trace mineral. Copper supports enzymes involved in energy production, iron metabolism, connective tissue formation, and nervous and immune system function.⁵

Who should avoid Copper sulphate?

• People with Wilson’s disease (a rare genetic disorder that causes copper to build up in the body) should avoid extra copper unless advised by their doctor.⁶
• Anyone told to limit copper by a healthcare professional should review labels and avoid copper-containing supplements or fortified products.

Myths & facts

• Myth: Copper sulphate is a “pesticide” in your food. Fact: While copper sulphate can be used in agriculture, food and drink uses are tightly controlled and involve very small amounts that meet food-grade specifications.
• Myth: Wine treated with copper is unsafe to drink. Fact: When used legally as a processing aid, strict limits on residual copper protect consumers.
• Myth: All copper additives are the same. Fact: Different copper salts have different properties; copper sulphate is just one of several permitted forms used for fortification or processing.

Copper sulphate in branded foods

You might see it on an ingredient list as:

• Copper sulphate
• Cupric sulfate
• E519

It most often appears in mineral premixes, fortified foods, or supplements. In wine, it may be used as a processing aid and not appear on the label, but residual copper is regulated.

References

Footnotes

1. Commission Regulation (EC) No 1170/2009 — Permitted vitamin and mineral substances for use in foods and food supplements (includes copper sulphate). https://eur-lex.europa.eu/eli/reg/2009/1170/oj ↩ ↩²

2. Commission Regulation (EC) No 606/2009 — Oenological practices and applicable restrictions (copper sulphate treatment; residual copper limits). https://eur-lex.europa.eu/eli/reg/2009/606/oj ↩ ↩² ↩³

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

4. Commission Regulation (EU) No 231/2012 — Specifications for food additives (includes E519 Copper sulphate). https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩²

5. Copper — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Copper-HealthProfessional/ ↩ ↩²

6. Wilson disease — NIH Genetic and Rare Diseases Information Center. https://rarediseases.info.nih.gov/diseases/5938/wilson-disease ↩