Culinary Notes
The Metallic Aftertaste: In baking, more is never better. If you use too much baking powder, the chemical reaction will not consume all of the alkaline base, leaving your sponge cake tasting bitter and metallic. Always measure precisely with flat, level spoons.
The Freshness Test: Baking powder degrades over time, especially in humid environments, which is the primary cause of flat, dense cakes. To test if your powder is still active, drop half a teaspoon into a small bowl of boiling water. It should fizz violently and immediately. If it merely bubbles weakly, throw it in the bin.
The Sifting Rule: Baking powder has a notorious tendency to form hard little pebbles in the tin. You must always sift it together with your flour. A concentrated lump of unmixed baking powder in a batter will create a massive, bitter air pocket in the finished bake.
The Rest Period: Because it is double-acting, you do not have to rush your batter into the oven quite as frantically as you do when using pure baking soda. However, leaving a mixed batter sitting on the counter for too long will still cause you to lose that precious first stage of carbon dioxide bubbles.
