This week I have a great question -- and hopefully a great answer! -- for you: What is the difference between baking soda and baking powder? Can you substitute one for the other?
Well, we can tell you from experience: no, you cannot substitute one for the other, gram for gram! Mixing up the two is probably the most common mistake in the kitchen here, and we know what the problem is as soon as we pull the product from the oven! If you do need a fast answer for how to handle a substitution, just skip to the end of this article.
So I think we all know baking soda and baking powder, besides their unfortunately similar names, share their action as leavening agents in common. But let's talk about the differences.
Actually, let's first take a good long look at some Muddy's cupcakes, made with good, old-fashioned double-acting baking powder. Mmm, Pucker Ups!
Now that you are back from your quick trip to Muddys, back to the question at hand! The quick answer is: baking soda is a carbonate. When a carbonate is combined with an acid, it releases carbon dioxide bubbles which cause the trademark texture of most of the baked goods you know and love. Baking powder is baking soda, a carbonate, already mixed with a dry acid so a secondary acid (such as buttermilk or lemon juice) is not required by the batter to create a rising effect.
And now the long answer, to help it stick in your head and mine!
Baking Soda came first. The chemical name is sodium bicarbonate (I'm sure we've all heard that somewhere, right?). The sodium element explains the somewhat salty taste of baking soda. Bicarbonate involves carbon atoms joined to oxygen atoms (and some hydrogen thrown in for good measure). Is it any wonder then, that when exposed to an acid, sodium bicarbonate releases carbon dioxide bubbles, causing yummy things to rise?
For a majority of the history of mankind, baking soda has not been available to bakers in the pure form granted us by Arm & Hammer. It first became available to the public in 1846, and there was much rejoicing among Victorians throughout the Western world! The REALLY old cookbooks call it 'saleratus,' but obviously that term has fallen out of fashion. The fabulous new saleratus allowed the invention of a variety of new recipes that would have been impossible before, including the modern day scone and cookies of a texture we would recognize today.
Victorians and American colonists did use a much inferior (in taste and effect) alternative to baking soda known as pearl ash. Prior to learning the process of making it from Native Americans, however, yeast was the only leavening agent known in Europe!
Like baking soda, pearl ash is a carbonate that must be combined with an acid to cause a rising reaction. Unlike baking powder.
Be thankful you're a baker now and not before Baking Powder became available in the 1860s! Before that, if you weren't relying on yeast for your leavening, you had to combine a carbonate (pearl ash or baking soda) and an acid. Your acids were usually homemade vinegars or 'clabbered' (or spoiled) milk, neither of which had a reliably consistent pH. Recipes could turn out differently each time! And we all know what happens when you combine vinegar and baking soda: volcano! The carbon dioxide is released immediately when a wet acid combines with baking soda, so a batter relying on the combination of the two needs to be baked relatively quickly before all the carbon dioxide is completely released.
Chemists saw bakers' need for a reliably consistent acid and, if possible, a dry one that would not react with a carbonate/baking soda until it was heated. And so baking powder was born! Baking powder is baking soda mixed with a dry acid, or two or three! Fast-acting baking powder is made with an acid that dissolves into a liquid and causes an immediate release of carbon dioxide into a wet batter. A slow-acting acid does not allow any release of carbon dioxide until the cake goes in the oven and is exposed to heat. A double-acting baking powder includes both slow-acting and fast-acting acids to provide two separate rises and thus, reliably fluffy baked goods. That's why we only use double-acting baking powder at Muddy's! One frustrating morning when we realized we had run out of our usual baking powder led to us discovering the hard way that single-acting baking powder just doesn't cut it!
As for substitutions:
If your recipe calls for baking soda and you only have baking powder: You already have an acid in your powder, so you really just need the carbonate component of the baking powder. With all the acidic ingredients in baking powder, you will have to use much more of it to get the amount of carbonate you need. You will need 2-3 times as much baking powder as your recipe dictates for baking soda, but remember those extra ingredients will affect the taste of your product! You can counter this by leaving out (or at least dramatically reducing) the salt, but you may or may not be satisfied with your finished product.
If your recipe calls for baking powder and you only have baking soda: No amount of baking soda alone will replace baking powder! A recipe containing baking powder does not contain enough acid to cause a reaction to plain old baking soda, so you must use a combination of baking soda and a dry acid. Just combine one part baking soda with two parts cream of tartar, and use the amount of your homemade baking powder called for by your recipe! So easy! Remember this will be a fast-acting, single-action baking powder, so it may act like your usual baking powder. Just get your cake or biscuits into the oven quickly, and it shouldn't be an issue!
And that should be all you ever wanted to know (and probably more) about baking soda and baking powder!