Understanding Raising Agents

Anything fluffy, from cake to mousse, needs a raising agent. This might be chemical, e.g. bicarbonate of soda, or purely air whipped into eggs. Bicarbonate of soda (also known as baking soda) works by reacting with acid to create carbon dioxide, causing existing air bubbles to expand and your bake to rise. It needs an acid in the mix such as buttermilk, yoghurt or cocoa to help it work and neutralise its soapy taste. Baking powder is bicarb with an acid already mixed in - cream of tartar. I like to use baking powder rather than self-raising flour so I can control the amounts (add 1 teaspoon baking powder to 100g/⅔ cup plain flour to make it self-raising). The key is to ensure it is fresh. If you have a tough bake, the most likely reasons are overmixing or out-of-date baking powder that has lost its oomph.