Baking powder is a leavening agent commonly used in baking to make bread and other baked goods rise. It works by producing carbon dioxide gas when it comes into contact with moisture and heat. This gas gets trapped in the dough or batter, creating bubbles, which then expand during baking and cause the bread to rise.
Baking powder is a combination of an acid, a base, and a filler (usually cornstarch). Most commonly, the acid used is cream of tartar (potassium bitartrate), and the base is baking soda (sodium bicarbonate). These two ingredients are dry and inert when separate, but when combined with moisture (such as water or milk) and heat, a chemical reaction occurs.
The reaction between the acid and the base in baking powder is called a double-acting reaction. It happens in two stages: once when it's mixed with the wet ingredients and again when it's exposed to heat during baking.
In the first stage, when baking powder is mixed with liquid, the acid and base react to produce carbon dioxide gas immediately. This gas helps to create bubbles and give the dough or batter some initial lift.
The second stage occurs when the dough or batter is exposed to heat in the oven. The heat causes the remaining baking powder to react, producing additional carbon dioxide gas. The gas continues to expand the existing bubbles, creating even more lift and resulting in a light and airy texture.
It's important to note that baking powder should be used in the correct proportions as specified in the recipe. Too little baking powder may result in a dense and flat texture, while too much can cause excessive rising and an unpleasant taste.
In contrast to baking powder, yeast is another leavening agent used in bread-making. Yeast is a living organism that ferments sugars, producing carbon dioxide gas as a byproduct. This gas is what causes the dough to rise over time. Unlike baking powder, yeast requires time for fermentation to occur, and it is commonly used in yeast bread recipes that involve longer rising periods.
So, while baking powder does not make bread rise after it's already cooked, it plays a crucial role in the rising process during baking by generating carbon dioxide gas, resulting in a lighter and more voluminous texture.