Ammonium Carbonate Powder, Bakers Ammonia (NH4)2CO3, It is used as a leavening agent and also as smelling salt. It can sometimes be substituted with baking powder in cookies recipe, but the finished product will never be as airy, but will make cookies or crackers extra-crisp.
Recommended Uses: 0.25%--1.5%
Yes, it has a very strong smell when baking, don't worry, It totally dissipates by the time the cookies are done.
