Baking Powder vs. Baking Soda

What are they, what do they do, and how are they different?

It's a common egg substitution to add 1/4 teaspoon baking soda along with 1/2 a mashed banana, or 1/2 cup applesauce, or another fruit puree. While the fruit puree acts like the moisture in the egg, helping to hold the batter together, the baking soda is the leavening agent, causing the cakey texture.

After today's zombie cupcake incident, I started thinking more about baking soda and baking powder, and why it turned my purple cupcakes into green zombies.

I'll be the first to admit that baking powder and baking soda are used somewhat interchangeably in my conversational vocabulary. When I mean to say I'm adding baking soda, 50% of the time I'll say baking powder, and vice-versa. After a little bit of research, I found that baking powder actually is made with baking soda.

Used in the kitchen, baking soda reacts instantaneously with acid in your batter to release CO2 that causes air bubbles in your baked goods. The batter rises and becomes cake-like.

However, baking powder has this acid component built in, and does not require additional acid (like apple cider vinegar) in order to activate.

Further research told me that not only acids, but starches as well can activate the CO2 release from both baking soda and baking powder. Thus, I am inclined to think that the heavy starch content of the Okinawan Sweet Potatoes reacted with the baking soda, and something about that reaction turned the purple potatoes into green ones.