Baking powder is a dry chemical leavening agent used in baking. When it comes in contact with acidic ingredient, it releases carbon dioxide gas, which forms bubbles and leavens the mixture it is in.

Common baking powder formulations include:

• sodium bicarbonate and cream of tartar
• calcium phosphate and sodium bicarbonate
• sodium bicarbonate and citric acid

Until as recently as the 1980s, many baking powders contained calcium aluminum phosphate or other aluminium salts. These have been phased out, as aluminum is now believed to be detrimental to human health at much lower levels than formerly thought.

See also: Baking soda