E224 - Potassium metabisulphite

At a glance

• What it is: A sulphite salt used as a preservative and antioxidant (also called potassium metabisulfite).
• What it does: Controls microbes, prevents oxidation and browning, stabilizes flavor and color in foods and drinks.
• Where it’s found: Common in wines and ciders, dried fruits, fruit juices/concentrates, syrups, and pickled products.
• E-number: E224 (European Union).
• Typical label names: “Potassium metabisulphite,” “Potassium metabisulfite,” “E224,” or “sulphites/sulfites.”

Why is Potassium metabisulphite added to food?

Food makers use E224 because it protects foods in two ways: it suppresses the growth of certain bacteria and yeasts, and it slows oxidation that leads to browning and stale flavors. In solution it forms bisulphite/sulphite ions and releases traces of sulphur dioxide, which deliver the preservative effect.¹

Winemakers rely on it to keep wine stable during production and storage. It helps preserve aroma and color and reduces the risk of spoilage organisms taking hold.¹

What foods contain Potassium metabisulphite?

You’ll most often see E224 in:

• Wines and ciders (and some other fermented beverages)
• Dried fruits (for example, apricots), jams, and fruit preserves
• Fruit juices and concentrates, cordials, and syrups
• Pickles, chutneys, and certain processed vegetable products¹

In the United States, many wines must declare “Contains sulfites” when total sulphur dioxide is at or above 10 parts per million (ppm).² More broadly, U.S. food labels must declare added sulfiting agents at 10 ppm or more.³

What can replace Potassium metabisulphite?

Depending on the food and the goal (antimicrobial vs antioxidant), makers may use:

• Other sulphites: sulphur dioxide, sodium metabisulphite, or potassium bisulphite
• Non-sulphite preservatives: potassium sorbate, sodium benzoate
• Antioxidants/acidulants: ascorbic acid, citric acid

Choice depends on taste impact, pH, product type, and local rules.

How is Potassium metabisulphite made?

Industry prepares E224 by reacting sulphur dioxide with a potassium base (such as potassium carbonate or hydroxide) to form potassium bisulphite, then removing water to yield potassium metabisulphite crystals.⁴

Is Potassium metabisulphite safe to eat?

Regulators evaluate sulphites as a group (E220–E228). The current health-based guidance value used by major bodies is an acceptable daily intake (ADI) of 0.7 mg per kilogram of body weight per day, expressed as sulphur dioxide. Some high-consuming groups (especially children who eat many sulphite-containing foods) can exceed this level in worst‑case scenarios, so authorities continue to monitor exposure.¹

Does Potassium metabisulphite have any benefits?

For consumers, the benefit is fresher-tasting food and drink with better color and a longer shelf life. In wine, it helps prevent oxidation and controls spoilage microbes so the wine stays stable from bottling to glass.¹

Who should avoid Potassium metabisulphite?

• People with sulphite sensitivity (including a subset of individuals with asthma) may experience wheezing, hives, or other reactions and should avoid sulphites or use medical advice to guide choices.⁵
• Labeling can help: in the European Union, “sulphur dioxide and sulphites” at 10 mg/kg or 10 mg/L (as SO2) or more must be indicated on the label; similar thresholds trigger disclosure in the United States.⁶³

Myths & facts

• Myth: “Sulfites are banned.” Fact: Sulphites are permitted in many foods and drinks, but their use is controlled and they must be declared when present at set levels.²⁶
• Myth: “Everyone reacts to sulphites.” Fact: Most people do not. Reactions occur in a small subset of people, especially some with asthma.⁵
• Myth: “Sulfites are just one chemical.” Fact: They’re a family, including sulphur dioxide and several sodium and potassium salts (E221–E228), such as E224.

Potassium metabisulphite in branded foods

How to spot it:

• Ingredient list: Look for “potassium metabisulphite,” “potassium metabisulfite,” “E224,” or “sulphites/sulfites.”
• Wine labels (U.S.): Bottles with 10 ppm or more must say “Contains sulfites.”²
• Food labels (U.S.): Added sulfiting agents at 10 ppm or more must be declared on the ingredient list.³
• Food labels (EU): “Sulphur dioxide and sulphites” are mandatory to declare when present at or above 10 mg/kg or 10 mg/L (as SO2).⁶

References

Footnotes

1. Re-evaluation of sulfur dioxide (E 220) and sulfites (E 221–228) as food additives — EFSA. https://www.efsa.europa.eu/en/efsajournal/pub/4438 ↩ ↩² ↩³ ↩⁴ ↩⁵

2. Mandatory label information; “Contains sulfites” — 27 CFR 4.32(e) (TTB/eCFR). https://www.ecfr.gov/current/title-27/part-4/section-4.32 ↩ ↩² ↩³

3. Food labeling; exemptions — 21 CFR 101.100 (eCFR). https://www.ecfr.gov/current/title-21/part-101/section-101.100 ↩ ↩² ↩³

4. Potassium metabisulfite — PubChem (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/516952 ↩

5. Sulfite sensitivity — MedlinePlus (NIH). https://medlineplus.gov/ency/article/002507.htm ↩ ↩²

6. Food Information to Consumers, Annex II (allergen list) — Regulation (EU) No 1169/2011 (EUR-Lex). https://eur-lex.europa.eu/eli/reg/2011/1169/oj ↩ ↩² ↩³