Question

What is ‘baking powder’? How does it make the cake soft and spongy?

Answer 1

Hint: Baking powder is a mixture of carbonate and weak acid or bicarbonate and weak acid. A buffering material is added to prevent the reaction of acid and base before their required use. Cornstarch is a buffer which can be added to baking powder. It increases the volume and lightens the texture of the cakes which makes them soft and spongy.

Complete answer:
Baking powder is a leavener which is used to improve texture and appearance of the baked things. The fluffy texture appears due to the creation of air pockets in the batter of the material which is to be fluffed. Baking powder produces gas bubbles in two stages. An initial set of gas bubbles is produced when baking powder is mixed with wet ingredients and the second set is produced after being heated. Heating the batter expands the bubbles thus creating a light texture. Baking powder releases carbon dioxide which get dissolved in the batter’s mixture. After saturation the carbon dioxide gas evolves into the air bubbles causing them to expand. This helps in setting a firm structure and thus spongy and fluffed cakes are baked by using baking powder.
The premature reaction of acid and base is prevented by adding a buffer or filler known as cornstarch.

Note:
A balance is required between batter and the leavening agent to maintain the correct pH value otherwise it can result in bitter taste of the recipe and cracks might appear making the overall texture dull. Baking soda and yeast are other examples of leaveners.