You don’t have to be a chemist to spot a certain pattern in the names of chemical leavening agents. Potassium carbonate. Potassium bicarbonate. Sodium carbonate. Sodium Bicarbonate. All are compounds that release CO2 when they’re either reacted with acids and/or degraded by heat. The logical question at this point is: are there any other carbonate salts out there that do the same job and that you can also safely eat?
Yes there is: ammonium carbonate (or sometimes bicarbonate) also known as “baker’s ammonia”. You mean people use ammonia in baking?? Well, sort of. A carbonate (or bicarbonate) salt of ammonia. If you’re German or Scandinavian you’ve probably heard of it: baker’s ammonia, also called hartshorn or “salt of hartshorn.” It gets that name because the original source of the compound was the antler of the male deer (hart). These days it’s industrially produced.
The interesting thing about baker’s ammonia is that it really does make your kitchen smell of ammonia during baking. However if you’re using it right all of the chemical evaporates out leaving nothing but the finished goods behind. What sort of goods? Usually very thin, crispy cookies like German springerle and/or Scandinavian ginger cookies, which owe part of their flavor to the shade of ammonia that the hartshorn leaves behind. I know, it sounds disgusting but don’t knock it until you’ve tried it.
If you can’t find any baker’s ammonia but want to make a recipe that calls for it, you can substitute baking soda. Since baker’s ammonia is a little more potent than baking soda you’ll need to add about 25% more soda to the mix. So, for every teaspoon of baker’s ammonia you’ll need to use 1 1/4 teaspoons of soda.
Be aware that baker’s ammonia shouldn’t be kept too terribly long as it can “spoil”, i.e. degrade into a mixture of ammonia and ammonium bicarbonate that smells pretty horrible and doesn’t do much for your cookies either.