Smelly powder, the scientific name of ammonium bicarbonate, is one of the chemical leavening agents, which is used in cakes that need to be puffed. It is hardly used in bread cakes. When heated, gas is generated, and the product is ammonia. Due to the high solubility of ammonia in water (1 volume of water can dissolve 600 volumes of ammonia), if ammonium bicarbonate is used in steamed products, it will make the finished products smell of ammonia, so it is generally used in fried products, so that ammonia is easy to volatilize at high temperature.