E503(II) · Ammonium Bicarbonate
- WHO
- Safe in moderation
- FDA
- Safe in moderation
- EFSA
- Safe in moderation
- FSANZ
- Safe in moderation
- Japan
- Safe in moderation
- UK FSA
- Safe in moderation
- Health Canada
- Safe in moderation
What is E503(II)?
Ammonium bicarbonate, also known as baker's ammonia or hartshorn, is a leavening agent used in crisp, flat baked goods like cookies and crackers. Unlike baking soda, it decomposes completely into gases (ammonia, carbon dioxide, and water vapor) during baking, leaving no salty aftertaste, though a temporary ammonia smell can occur if the product isn't baked thoroughly or is very thick.
Also appears on labels as: Ammonium bicarbonate, E503(i), E503(ii), E 503(ii), E-503(ii), INS 503(ii), ABC, Ammonium hydrogen carbonate, Carbonic acid, ammonium salt, Ammonium acid carbonate, NH4HCO3, Ammonium carbonate (basic).
What the evidence says
- Generally recognized as safe at typical food levels once fully baked off.
- Can produce a strong ammonia odor during baking that may be irritating if inhaled directly in an enclosed space, though this dissipates as baking completes.
Frequently asked questions
Is E503(II) safe?
Our overall verdict for E503(II) (Ammonium Bicarbonate) is “Safe in moderation”, based on the most cautious of the major regulators’ positions — FDA: safe in moderation; WHO: safe in moderation; EFSA: safe in moderation; FSANZ: safe in moderation; Japan: safe in moderation; UK FSA: safe in moderation; Health Canada: safe in moderation.
Is E503(II) vegan, halal or gluten-free?
According to our ingredient data for Ammonium Bicarbonate — vegan: yes, vegetarian: yes, halal: yes, kosher: yes, gluten-free: yes, dairy-free: yes. Manufacturing sources can vary between products; check the label if it matters to you.
What is E503(II) and why is it used?
Ammonium bicarbonate, also known as baker's ammonia or hartshorn, is a leavening agent used in crisp, flat baked goods like cookies and crackers. Unlike baking soda, it decomposes completely into gases (ammonia, carbon dioxide, and water vapor) during baking, leaving no salty aftertaste, though a temporary ammonia smell can occur if the product isn't baked thoroughly or is very thick.
Does E503(II) contain allergens?
No known allergens are recorded for Ammonium Bicarbonate.
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This page summarises publicly available regulatory assessments and research. It is general information, not medical advice. Sources: EFSA, FDA, WHO and the studies linked above.