baking powder 1/2 tsp

Baking powder is a dry leavening agent composed primarily of a base (usually sodium bicarbonate), one or more acids (commonly cream of tartar or sodium aluminum sulfate), and a filler (typically cornstarch) to absorb moisture. It was developed in the 19th century as a convenient alternative to yeast and soda-saleratus combinations. When combined with liquid and heat, the chemical reaction between the base and acid produces carbon dioxide gas, creating the lift and aeration necessary for baked goods to rise. Most commercial baking powders are "double-acting," releasing gas both when moistened and when exposed to heat.

Single-acting and double-acting varieties exist, with the latter dominating modern baking due to greater reliability and flexibility in preparation timing.

Baking powder is the primary leavening agent in quick breads, cakes, cookies, muffins, pancakes, and biscuits across countless culinary traditions. It provides reliable, predictable rise without the fermentation time required by yeast-based products. It is typically mixed with dry ingredients before adding wet components, allowing the baker to control rising and baking time precisely. In recipes, baking powder is often paired with acidic ingredients (buttermilk, sour cream, yogurt) to enhance its leavening action, or used alone when recipes contain non-acidic liquids.