For baking soda, which is a common ingredient of baking powder, see Baking powder can be replaced by bicarbonate. For the stream in Montana, see Baking Powder Creek. This particular type of baking powder contains monocalcium phosphate, sodium bicarbonate, and cornstarch.

Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used instead of yeast for end-products where fermentation flavors would be undesirable, where the batter lacks the elastic structure to hold gas bubbles for more than a few minutes, and to speed the production of baked goods. Baking powder is made up of a base, an acid, and a buffering material to prevent the acid and base from reacting before their intended use. When combined with water, the sodium bicarbonate and acid salts react to produce gaseous carbon dioxide. Whether commercially or domestically prepared, the principles behind baking powder formulations remain the same. H2O The real reactions are more complicated because the acids are complicated.

The use of two acidic components is the basis of the term “double acting”. The acid in a baking powder can be either fast-acting or slow-acting. A fast-acting acid reacts in a wet mixture with baking soda at room temperature, and a slow-acting acid does not react until heated. By providing a second rise in the oven, double-acting baking powders increase the reliability of baked goods by rendering the time elapsed between mixing and baking less critical.

This is the type of baking powder most widely available to consumers today. For example, Rumford Baking Powder is a double-acting product that contains only monocalcium phosphate as a leavening acid. With this acid, about two-thirds of the available gas is released within about two minutes of mixing at room temperature. It then becomes dormant because an intermediate species, dicalcium phosphate, is generated during the initial mixing. Baking powders also include components to improve their stability and consistency. Cornstarch, flour, or potato starch are often used as buffers. Baking powder is made with two main components an acid and a base, when they are hydrated an acid – base reaction occurs releasing CO2.

The effectiveness of such leavenings varied widely. Resulting baked goods often had a sour or bitter taste. Breads were made of grain, water, yeast, and sometimes salt. Cooks also made yeast, sponge and pound cakes. Yeast cakes were similar to breads but included fancier ingredients, like sugar, spices, fruits or nuts. Sponge cakes used beaten egg whites for leavening.

The third type of leavening, pearlash, was the precursor to modern baking powder. Pearlash was a purified form of potash. It was first used as a leavening agent by Native Americans and was the subject of the first patent in the United States, issued in April 1790. Between the publication of American Cookery in 1796, and the mid-1800s, cooks experimented with a variety of acids, alkalis, and mineral salts as possible chemical leaveners. Many were already available in households as medicinal, cleaning or solvent products.

Baking soda and cream of tartar were relatively new ingredients for cooks: Soda may have been introduced to American cooking by female Irish immigrants who found work as kitchen help. Cream of tartar, also known as tartaric acid or potassium bitartrate, was a by-product of wine-making and had to be imported from France and Italy. There were recipes for a “crust” similar to modern dumplings or cobbler, several for cakes, and one for “soda doughnuts”. When the third edition of Miss Beecher’s Domestic Receipt Book appeared in 1858, it included 8 types of leaveners, only two of which could be made at home. Baking soda and cream of tartar were sold by chemists rather than in grocery stores.