Baking powder
Baking powder is a dry chemical leavening agent used in baking. There are several formulations; all contain an alkali, typically sodium bicarbonate (baking soda), and an acid in the form of salt crystals, together with starch to keep it dry. When dissolved in water the acid and alkali react and evolve carbon dioxide gas, which forms bubbles and leavens the mixture. Most modern baking powders contain two acid salts, one which reacts at room temperature, producing many small bubbles as soon as the dough is prepared, and another which reacts at a higher temperatures, expanding the bubbles during baking.
Common low-temperate acid salts include cream of tartar, calcium phosphate, and citrate. High-temperature acid salts are usually aluminium salts, such as calcium aluminum phosphate. However, aluminum is now believed to be detrimental to human health at much lower levels than formerly thought, and many baking powders now omit these.
Baking powder was invented by Eben Norton Horsford, a student of Justus von Liebig, who began his studies on baking powder in 1856. Rudolf Oetker, a German pharmacist, made baking powder very popular when he began selling his mixture to housewives. The same recipe he invented in 1893 is still sold as Backin in Germany. Oetker started the mass production of baking powder in 1898 and patented his technique in 1903.
