E923 - ammonium persulfate

At a glance

• What it is: an oxidizer and flour treatment agent used to improve dough handling
• Also called: ammonium peroxydisulfate; INS 923
• Where you might see it: wheat flour and some bakery items in places where it’s approved
• Label names: “ammonium persulfate,” “ammonium peroxydisulfate,” or “E923”
• Notes: authorization and use levels vary by country

Why is ammonium persulfate added to food?

Food makers use oxidizing flour treatment agents to improve the baking quality of flour and dough. In that role, ammonium persulfate helps condition dough so it handles better during mixing and can bake more consistently.¹

INS stands for International Numbering System, a list maintained by the Codex Alimentarius Commission (a joint program of the Food and Agriculture Organization, FAO, and the World Health Organization, WHO) to harmonize names and functions of food additives worldwide.¹

What foods contain ammonium persulfate?

Where its use is authorized, E923 may appear in wheat flour and some bakery products as a flour treatment agent. If present, it is typically listed as “ammonium persulfate” or “E923” on the ingredient label.¹

What can replace ammonium persulfate?

Bakers and millers have several alternatives, depending on recipe and local rules:

• Ascorbic acid (vitamin C): ascorbic acid
• Enzymes: glucose oxidase
• Reducing/conditioning agents: L-cysteine
• Mineral improvers: calcium sulfate
• Other oxidizers used in some markets: azodicarbonamide, potassium bromate

The best choice depends on the flour type, dough process, and the regulations where the food is sold.

How is ammonium persulfate made?

Industrial production typically uses electrolysis: ammonium sulfate is oxidized in an acidic solution to form ammonium persulfate crystals, which are then purified and dried.² The compound is a white, odorless solid and a strong oxidizer.²

Is ammonium persulfate safe to eat?

Food-grade use is limited to very small amounts when authorized, and international specifications exist to control identity and purity. Codex Alimentarius lists ammonium persulfate (INS 923) as a flour treatment agent in its database of food additives, which countries may use when setting their own rules.³

Outside of food use, persulfates are well-known irritants and sensitizers. Occupational exposure (for example, to hair-bleaching powders) has been associated with skin and respiratory irritation and allergic responses.⁴⁵ These hazards concern handling concentrated powders, not the tiny levels used as a flour aid, but they matter for anyone who works with the pure substance.

Does ammonium persulfate have any benefits?

As a flour treatment agent, its purpose is to improve the baking quality of flour and dough, supporting more reliable processing and finished bread quality.¹ Manufacturers typically select it, or an alternative, to achieve consistent dough strength and texture in a given recipe.

Who should avoid ammonium persulfate?

• People with known sensitivity or allergy to persulfate salts should avoid exposure to the pure powder and products containing it.
• Workers who handle persulfates (for example, in salons or manufacturing) should follow workplace safety guidance to prevent skin contact and inhalation.⁴⁵
• Consumers with concerns can check labels for “ammonium persulfate” or “E923.”

NIOSH stands for the U.S. National Institute for Occupational Safety and Health; ECHA is the European Chemicals Agency. Both provide hazard information relevant to occupational exposure.⁴⁵

Myths & facts

• Myth: E923 is the same as “sulfites.” Fact: Persulfates are different chemicals from sulfites; they belong to different families and behave differently in food and the body.
• Myth: If it’s on the label, bread will contain lots of it. Fact: Flour treatment agents are used at very low levels to adjust dough properties.
• Myth: It’s either globally allowed or globally banned. Fact: Authorization and maximum levels vary by country and food category; always check local regulations.

ammonium persulfate in branded foods

You may see E923 on some flour or bread labels in markets where it is permitted. Look for “ammonium persulfate,” “ammonium peroxydisulfate,” or “E923” in the ingredient list. If you want to avoid it, choose products that do not list it or that use alternatives such as ascorbic acid or glucose oxidase.

References

Footnotes

1. Class names and the International Numbering System for Food Additives (CAC/GL 36-1989) — Codex Alimentarius. https://www.fao.org/fao-who-codexalimentarius/sh-proxy/en/?lnk=1&url=https://workspace.fao.org/sites/codex/Standards/CXG%2036-1989/CXG_036e.pdf ↩ ↩² ↩³ ↩⁴

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

3. General Standard for Food Additives (GSFA) Online — Codex Alimentarius. https://www.fao.org/gsfaonline/ ↩

4. NIOSH Pocket Guide to Chemical Hazards: Ammonium persulfate — CDC/NIOSH. https://www.cdc.gov/niosh/npg/ ↩ ↩² ↩³

5. Ammonium persulfate: Harmonised classification and labelling (respiratory and skin sensitiser, irritant) — European Chemicals Agency (ECHA). https://echa.europa.eu/registration-dossier/-/registered-dossier/15595 ↩ ↩² ↩³