So you've noticed that sometimes when you're baking something, the recipe calls for baking powder, while other times it wants you to add baking soda and something weird like lemon juice or vinegar. Other times, you're asked to add both baking powder and baking soda to the recipe…what gives!?
If you're interested in the science behind the food you love to cook and eat but have never really thought to look into it, you've landed in the right place.
My name is Jeff Potter, author of Cooking for Geeks, and today's quick lesson in gastronomy will cover some of the differences between baking soda and baking powder.
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Step 1: The Agents - How They Work
Here they are. On the left, good old-fashioned baking soda, or sodium bicarbonate. On the right, baking powder, which is a combination several different compounds.
The quick answer to how leavening agents work is that they cause the batter that we use to make cakes and breads (among other things) to rise. This is accomplished by the leavening agents creating gas (usually CO2), which when incorporated into the dough makes the dough rise and your baked goods turn out light and fluffy.
Step 2: Baking Soda
Baking soda is pure sodium bicarbonate, or "soda bic" as it is sometimes affectionately called. When placed in a glass of water, it will not cause any significant gas-like reaction. So how and why is it used in so many recipes, you ask?
In order to inspire it to do its "thing", baking soda needs to have an acid compound added to it. When it does come into contact with an acid, stand-back. This is the bubble-fest you've been waiting for.
Incidentally, this is the same technology used to create those grade school science fair volcanoes that are still making the rounds.
Step 3: Baking Powder
Baking powder on the other hand, is a self-contained leavening system. Scoop some baking powder into a cup full of water, and you will see an instant reaction.
Step 4: Which Do I Use?
In order to optimise the bubble factor and therefore, the texture of your baked goods, make sure that if you are using baking soda as your primary leavening agent, use an acid (like vinegar or buttermilk) to activate it.
Baking powder is ready to use right out of the can, and therefore it is often the more recommended leavening agent. It's quick, easy, and no-fuss.
Step 5: Check Out the Book!
If you like thinking about the science behind your food, check out Cooking for Geeks, where you can find the information in this intractable on page 243. Also, visit the Cooking for Geeks webpage by clicking here, and read two chapters for free! If you enjoyed this instructable and video, please like and subscribe to my YouTube channel for more scientifically-minded gastronomic delights!