Ammonium Carbonate in Baking

Close up of white powdery substance in a measuring spoon


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Ammonium carbonate is used for leavening in cookies, flat biscuits, or crackers. In German baking, it's known as hirschhornsalz or hartshorn, and it is also called baker's ammonia. It is not used for cakes since the gaseous ammonia given off during baking cannot escape the thicker, higher batters and would make the baked goods smell bad. It leaves no salty or soapy taste residue as baking powder sometimes does since it completely decomposes into ammonia and carbon dioxide.

Advantages of Ammonium Carbonate in Baking

Ammonium carbonate lends a distinctive crispness and lightness to the baked good, which why it is still listed in certain recipes, despite the overwhelming use of baking powder and baking soda in modern baked goods. You can substitute baking powder for ammonium carbonate in a pinch, but the final baked product may not have the same texture. The designs on molded cookies are also said to keep their shape much better when ammonium carbonate is used.

Using Ammonium Carbonate

Usually, ammonium carbonate is mixed in with the liquid before adding to the dry ingredients, so that it dissolves well and mixes thoroughly. It must be stored dry, in a well-sealed container, because it absorbs moisture easily and clumps, To tell if it is still active, place a small amount in hot water. If it bubbles vigorously, you can use it in your recipes.


If ammonium carbonate is not available, baking powder can be substituted in a 1-to-1, 1-to-2, or 1-to-3 ratio. You can also add some baking soda together with the baking powder.

History of Ammonium Carbonate

Hirschhornsalz was made in the Middle Ages by burning or dry distillation of keratin-containing materials (keratin is a structural protein found in the animal kingdom). They did this by heating shredded horns, hooves, antlers, skin, and even decomposed primate urine in lime kilns (Kalköfen), which were ovens built for heating limestone (calcium carbonate). This is a manufacturing process which goes back to Greek and Roman times to make quicklime, a building material. 

The residue was collected after the ovens cooled off. Since wood ash was often boiled in water and used as a leavening agent, it is possible that these ashes were used in the same way. Hartshorn was used to treat diarrhea, dysentery, fevers, and many different types of bites. The name was of particular importance in the Middle Ages when people believed that the salt collected from burning particular parts of the animal had special, medicinal value. It was a common smelling salt in Victorian times.

Production and Chemistry

Today, the white powder is chemically produced by heating ammonium chloride or ammonium sulfate with chalk. Hirschhornsalz is a mixture of three molecules:

  • Ammonium carbonate (NH4 )2CO3 → 2NH3 + CO2 + H2 O
  • Ammonium bicarbonate NH4 HCO3 → NH3 + CO2 + H2 O
  • Ammonium carbonate (second form) NH4 NH2 CO2 → 2NH3 + CO2

These molecules break down into the gases ammonia, carbon dioxide, and (water) steam when heated to 140 F (60 C) or higher. The gases lift the dough or batter (which has air bubbles in it through creaming) before the batter is set as they rise towards the surface of the cookie. As the dough sets up, the bubbles remain but the ammonia, carbon dioxide, and steam are dispersed from the baked good and into the air in the kitchen.

Baker's ammonia can react with certain sugars and amino acids in the dough to make small amounts of acrylamide, a carcinogen.

Recipes With Ammonium Carbonate

If you want to see how this ingredient is used, try making these cookies:

  • Polish Ammonia Cookies: These rolled sugar cookies have a crisp texture due to ammonium carbonate.
  • Basler Leckerli: This Swiss-German Christmas gingerbread cookie will keep for weeks. It is dry and filled with nuts and candied orange peel.
  • Spekulatius Cookies: These are a traditional Christmas spice cookie in Germany and are also called spekulaas in the Netherlands. They are traditionally formed in a wooden mold, but you can use cookie cutters instead.

Alternate Spellings

  • ABC-Trieb (Ammonium-bi-carbonate)
  • E503ii (EU food additive)
  • Baker's ammonia
  • Hart's horn
  • Hartshorn
  • Hornsalt
  • Bicarbonate of ammonia
  • Ammonium hydrogen carbonate
  • AmBic
  • Powdered baking ammonia, bicarbonate salt of ammonia
  • Salt of hart’s horn
  • Hjortetakksalt