E-numbers / Other additives / E503
also: Ammonium carbonate · Ammonium bicarbonate · Ammonium hydrogen carbonate · Baker's ammonia
Baker's ammonia. It makes biscuits and crackers rise, then turns entirely into gas in the oven, so none is left in the food.
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Gluten Free Wholegrain Oats (72%), Cheese (15%) (Milk), Sustainable Palm Fruit Oil, Sea Salt, Raising Agents (Sodium Bicarbonate, Ammonium Bicarbonate)
Ammonium carbonates are a group of ammonium salts, mainly ammonium bicarbonate, made by bubbling carbon dioxide and ammonia through water.
UK supermarket foods that declare E503: 1,185 of the 43,325 we checked (2.7%)
Counted by its code or its name in the ingredient list.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Ammonium carbonates are a group of ammonium salts, mainly ammonium bicarbonate, made by bubbling carbon dioxide and ammonia through water. It is a white powder with a faint smell of ammonia. Its old names are baker's ammonia and hartshorn salt, because it was once made from deer antler.
Above about 60 degrees Celsius it breaks down into three gases: ammonia, carbon dioxide and water vapour. All three escape from the dough as it bakes, leaving nothing behind. The gas makes bubbles that set as the biscuit cooks, giving a light, open texture. Unlike baking powder it leaves no salty or sour taste. It is only used in thin, dry bakes, where all the ammonia can escape.
Dry biscuits, crackers, cream crackers, rich tea biscuits, gingerbread, amaretti, speculoos, and some traditional flatbreads and wafers. It is not used in cakes or loaves, because the ammonia cannot escape from a thick bake and leaves an off taste. UK labels call it ammonium carbonates, ammonium bicarbonate, raising agent (E503) or raising agent (503).
What sets E503 apart is that it breaks down entirely into gases at baking temperatures, leaving nothing in the finished food. That is unlike sodium-based raising agents.
Ammonium bicarbonate breaks down completely above about 60 degrees Celsius into ammonia, carbon dioxide and water. No ammonium salt stays in properly baked, dry products.
European reviewers looked at ammonium carbonates in 2018, as part of re-checking every additive approved before 2009. They set no numerical daily limit.
Reviewers set no numerical daily limit for ammonium carbonates.
Daily limit. None set.
People with rare disorders in how the body handles ammonia, such as urea cycle disorders, are sometimes told by their doctor to limit ammonium from all sources. Anyone told to restrict ammonium should check with their healthcare team about biscuits and crackers listing raising agent (E503) or ammonium bicarbonate.
The science is simple: it breaks down in the oven and nothing remains in the finished biscuit or cracker. The practical question is whether the ammonia escapes fully, which depends on the bake being thin and dry.
No. Ammonium carbonates are approved in the UK and have kept that approval since the UK left the EU.
In properly baked, thin, dry products such as biscuits and crackers, the ammonia escapes as a gas and is not in the finished food. European reviewers confirmed this in 2018. It is not used in thick, moist bakes like loaves, because the ammonia cannot escape and would spoil the taste.
Dry biscuits, cream crackers, rich tea biscuits, gingerbread, amaretti, speculoos, wafers and similar thin bakes. Look for ammonium carbonates, ammonium bicarbonate or raising agent (E503).
Yes. It is made from ammonia and carbon dioxide, with nothing from animals.
Last reviewed: 9 November 2026
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