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 emit carbon dioxide gas, which expands existing bubbles to leaven the mixture. Most modern baking powders are double acting, that is, they contain two acid salts, one which reacts at room temperature, producing a rise as soon as the dough or batter is prepared, and another which reacts at a higher temperature, causing a further rise during baking. Baking powders that contain only the low-temperature acid salts are called single acting. Most recipes call for a mixing procedure that is designed to introduce many tiny air bubbles, for example, "cream the butter and sugar", which the leavening gas from baking powder will expand.

Common low-temperature acid salts include cream of tartar, calcium phosphate, and citrate. High-temperature acid salts are usually aluminium salts, such as calcium aluminum phosphate. They can be found not only in many baking powders, but also in many non-dairy coffee creamers. While dietary aluminium is not known definitively to be detrimental to human health, baking powders are available without it for people who are concerned, and also for those sensitive to the taste.

While various baking powders were sold in the first half of the 19th century, our modern variants were discovered by Alfred Bird. Eben Norton Horsford, a student of Justus von Liebig, who began his studies on baking powder in 1856, eventually developed a variety he named in honor of Count Rumford. August Oetker, a German pharmacist, made baking powder very popular when he began selling his mixture to housewives. The same recipe he created 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.

Usage

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Baking powder is most often found in quick breads like pancakes, waffles, and muffins. Generally, one teaspoon of baking powder is used to raise a mixture of one cup of flour, one cup of liquid, and one egg. However, if the mixture is acidic, baking powder's additional acids will remain unconsumed in the chemical reaction and often lend an unpleasant chemical taste to food. High acidity can be caused by ingredients like buttermilk, lemon, yoghurt, citrus, or honey. When excessive acidity is present, some of the baking powder is replaced with baking soda. For example, one cup of flour, one egg, and one cup of buttermilk requires only ½ teaspoon of baking powder -- the remaining leavening is caused by buttermilk acids reacting with ¼ teaspoon of baking soda.

Substituting in recipes

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Baking powder is generally just baking soda mixed with an acid, and a number of kitchen acids may be mixed with baking soda to simulate commercial blends of baking powder. The most common suggestion is to use two parts cream of tartar with one part baking soda. However, nutritionists such as Erica White caution against excessive consumption of cream of tartar, claiming that it is highly toxic. Where a recipe already uses buttermilk or yoghurt, baking soda can be used without cream of tartar (or with less). Alternatively, lemon juice can be substituted for some of the liquid in the recipe, to provide the required acidity to activate the baking soda.

English inventions | Leavening agents

Backpulver | Levure chimique | אבקת אפייה | Bakpoeder | ベーキングパウダー | Bakepulver | Proszek do pieczenia | Leivinjauhe