Baking powder is a chemical leavening consisting of a mixture of an acid reacting material and sodium bicarbonate. A starch, usually cornstarch, is added to standardize the mixture and keep it dry. This prevents the acid and soda from reacting with each other in the can.
There are four types of baking powder: tartrate, phosphate, anhydrous phosphate, and sodium aluminum sulfate phosphate. All four types contain a starch and baking soda but the acid salt ingredient differs.
Tartrate Baking powders contain the acid ingredients cream of tartar and tartaric acid. The first baking powders sold were this type. These baking powders are known as single action because they are quick to react as soon as moistened. Much of the gas is given off during mixing and the remainder is released during baking. Because all of this happens as a continuous reaction, speedy handling of the batter from bowl to oven is essential so that as much of the rising action as possible takes place in the oven.
Phosphate baking powders contain calcium or sodium phosphate as the acid salt. These release a fair amount of the carbon dioxide in the cold mixture. The rest is released during baking.
Anhydrons phosphate baking powders have anhydrous monocalcium phosphate as their acid ingredient. This acid salt has been treated to slow down the rate at which it dissolves. Little carbon dioxide is released during mixing. Carbon dioxide production accelerates early in the baking period. This type of baking powder is not sold extensively on the retail market but is widely used in packaged mixes.
Sodium aluminum sulfate phosphate baking powders contain sodium aluminum sulfate and calcium phosphate, as acid salts. Since sodium aluminum sulfate reacts slowly with baking soda, the phosphate is added to speed up the reaction. Baking powders of this type are considered double action because the phosphate reacts with the baking soda while the mixture is cold, whereas heat is necessary before the sulfate reacts. About 85 percent of baking powders sold on the retail market are sodium aluminum sulfate phosphate. Unless another type of baking powder is specified, a double action product is intended in most recipes.
Baking powder is a small ingredient in a recipe yet it has great influence on the shape, volume, grain, texture, and lightness of the finished product.
Accurate level measurement of baking powder is very important. The exact amount a recipe calls for gives the product the best texture and volume. Too little baking powder makes baked foods heavy and compact. Too much can cause over rising followed by collapse, coarse loose texture, and often a lingering baking powder taste. As a general guide, one to two teaspoons of baking powder should be used for every cup of flour in a recipe.
