Ammonium bicarbonate, also known as hartshorn or baker’s ammonia, is a white powdered chemical that is generally used as a leavening agent in baking recipes. A leavening agent is any chemical substance that makes batter and dough rise and prevents them from becoming dense by adding air bubbles as the item bakes. Ammonium bicarbonate was used more often prior to the eighteenth century with the inventions of other leavening agents, baking soda and baking powder.
When ammonium bicarbonate is added to batter or dough and exposed to heat from an oven, the high temperature will begin to activate the chemical and cause a reaction. After the chemical bakes, it begins to gradually produce ammonia gas within the baked good. The ammonia gas makes small bubbles and allows air into the batter or dough, making the product lighter and fluffier. Without the use of the leavening agent or other substitute, certain baked goods would have a hard texture and be overly dense.
Although ammonium bicarbonate is usually successful at giving baked goods light, flaky textures, it can also impart a strong taste if used in large amounts. The strong, bitter taste is due to the reaction of the ammonia gas. As the gas continues to heat, its flavor is significantly reduced. Baked goods that are very thick, such as cakes and loaves of bread, are most likely to retain the ammonia taste because the gas taste may not have enough time to cook out since it is spread out over a larger area. Smaller items, such as cookies, crackers, or small pastries, are more successful with the leavening agent because its smaller surface area allows the gas enough time to cook out of each individual baked good.
Ammonium bicarbonate can have an extended shelf life of several years if stored properly in an airtight container. Storage containers that can effectively keep the leavening agent include airtight jars and canisters. If the substance is exposed to warm temperatures, the heat could cause the ammonia chemicals to activate while it is being stored, which would make it ineffective if it was added to batter or dough. The effectiveness of the leavening agent can be determined by adding it to an acid, such as vinegar or lemon juice. If it is still effective and able to be used in dough or batter, it will bubble when it comes into contact with acid.