E503: Ammonium hydrogen carbonate

What is E503?

Ammonium hydrogen carbonate, also called ammonium bicarbonate or baker's ammonia, is a white crystalline salt. Listed as E503(ii), it breaks down when heated into ammonia, carbon dioxide and water, all of which escape as gases.

Origin and production

It is manufactured by reacting ammonia with carbon dioxide in water; a similar salt was once distilled from deer antler, hence the old name hartshorn.

Why is it used?

It is a raising agent prized for thin, dry baked goods such as crackers, flat biscuits and crisp cookies, where the gases escape fully during baking and leave a light, crunchy texture. It is less suitable for thick, moist products, where the ammonia smell could remain.

Vegan, vegetarian and halal

Modern ammonium hydrogen carbonate is made synthetically from mineral raw materials and is suitable for vegans and vegetarians. It is not normally a concern for halal or kosher diets, though product certification gives the final answer.

Safety and regulation

It is authorised as a food additive in the EU without a numerical limit for its permitted uses. Because it decomposes almost completely during baking, very little of it remains in the finished product.

Common in