Ammonium Carbonate
What it does
Raising agent (baker's ammonia).
How it's made
Manufactured.
Ammonium carbonate (and the closely related ammonium bicarbonate) is a traditional raising agent, sometimes called baker's ammonia or hartshorn, used especially for thin, crisp baked goods such as some biscuits and crackers. It leavens powerfully and leaves no salty residue, which suits low-moisture bakes.
It is manufactured by combining ammonia and carbon dioxide with water under controlled conditions, which produces ammonium carbonate and bicarbonate. The gases are passed together so they react and the product condenses or crystallises out, then it is collected and purified.
The result is a white crystalline solid with a sharp ammonia smell. When heated in the oven it breaks down completely into ammonia, carbon dioxide and water vapour — all gases — which is what makes baked goods rise and then escape entirely, provided the item is thin enough for the ammonia to bake off. In thick, moist bakes it would leave an ammonia taste, so it is reserved for crisp, dry products.
Possible reactions
Generally safe in baked foods.