When to use baking powder vs. baking soda

I like to experiement in the kitchen, and am sometime daring enough to try a little baking, which is generally less forgiving. Where I often get stuck is not knowing when to use baking soda, and when to use baking powder. It is clear enough when following a recipe, but when messing around, which should I use when? What is the difference?

I know that baking soda is a single compound – sodium bicarbonate – and that baking powder is a mixture which includes baking soda and some other things. But functionally, what is the difference?

This page explains it more concisely than I can:

According to pulykamell in this thread, baking powder is

“Sodium bicarbonate and cream of tartar. When moisture is added, the tartar forms an acid which reacts with the baking soda, forming bubbles which makes whatever you’re cooking rise. If what you’re making already has an acidic substance in it, usually only baking soda is called for, since your acid (beit lemon juice or whatever) will act as cream of tartar would.”


Rule of thumb:

For things that rise up (cakes) - baking powder

For things that spread out (cookies) - baking soda

Thanks all for your definitive answers. I just figured out how to use the SDMB search function correctly,:smack: and see now that this was already discussed earlier. Sorry for the repeat.

Now, to hijack my own thread, can anyone explain to me how yeast fits into this picture?

From that site mentioned:

I’ver never heard the rise-up/spread-out distinction, but I do have a question: Most cookie recipes I’ve seen do use baking soda, but what acid is it reacting with? The only suspects I see are milk (not soured,though) and brown sugar (is this acidic)?

pulykamell: Brown sugar and milk are both acidic. Brown sugar is probably the more important one here.

Chocolate & cocoa are both mildly acidic; I know of at least one chocolate cookie recipe that doesn’t use any baking powder at all.

yeast has to be active, that is, alive. You give it some liquid and sugar to live in and eat and it starts giving off gas bubbles.

When you bake something, these gas bubbles get trapped in the structure of the dough creating little spaces, these spaces are what you see when you tear apart a piece of bread and see airholes.

Beaten eggs play the same role in cakes. The egg traps air and as the dough cooks and stiffens, you get little spaces where the air bubbles were.

Otherwise you’d have flat, dense hard bricks that would break your teeth.

Thanks White Ink. When would yeast be used, as opposed to baking soda or baking powder?

Baking soda will also outgass CO2 when heated.

If you really want to get to the bottom of this I recommend that you have a look at On Food and Cooking, by Harold McGee. (that’s probably the fifth time I recommend that book this week.) He has a very good chapter on baking, where he describes what goes on in a dough as well as a batter, all the way from grinding the grain to the bread going stale.
Simply: a yeast-containing dough utilizes gelatinized starch, reinforced by gluten, to keep in the CO[sub]2[/sub] which the yeast generates over the hour-long ‘proving’. As the process takes rather long, the structure has to be rather sturdy and impermeable.
A baking powder/soda containing batter, on the other hand, doesn’t need the gluten, as the gasses are created much quicker, and the starch sets straight away. A lot of the gasses are produced while the cake is in the oven.

As pointed out earlier, baking powder is baking soda mixed with an acid, normally cream of tartar. The baking soda gives out CO[sub]2[/sub] when exposed to water and acid (and heat). If the batter is acidic enough, you might not need the 'powder. In fact almost all usual ingredients are acidic - but maybe not acidic enough. (In fact, the only alkaline things you’ll find in a kitchen are egg whites and baking soda.)

Again, Try to find that book. If you’re into ‘experimenting in the kitchen’, it’s worth its weight in, maybe not gold, but at least sugar.

Thanks Popup, for the explanation and the reference. The book looks totally awesome, and I am going to put it right on the top of my Christmas list!

Isn’t cocoa basic, also? I know that this is contrary to what MikeS said, but I think that was a typo (especially considering his statement that it can sometimes replace baking soda). And certainly cocoa tastes bitter. I didn’t know about the egg whites, though.

pulykamell, you may not have known this, but molasses is what makes brown sugar brown. So since molasses is acidic, so is brown sugar.

It seems that chocolate is acidic from the info I could find.

From here.

Thanks for the bit about brown sugar. I could have sworn I’d read that somewhere but had completely forgotten.

This is worth highlighting. Many people believe that brown sugar is somehow ‘more natural’, and less refined. In fact, nowadays, brown sugar is simply normal white sugar that has been flavoured with some molasses.
I’m out on a limb here, but I would have thought that (a solution of) sucrose (white sugar) by itself is slightly acidic. I can’t find any good reference right now though, so don’t quote me on that.

If you want to make your own baking powder, the recipe is 1/2 cup of cream of tarter and 1/4 cup each of baking soda and cornstarch.

Chronos: No, I’m pretty sure that chocolate, at least, is acidic. Try melting a square of baker’s chocolate sometime and stirring in a quarter-teaspoon of baking soda; you’ll find that the chocolate becomes light and sponge-like. (I did this once while I was preparing a chocolate cake, and was surprised at the result.)

What I was driving at in my previous comment was that the only candidates for leavening in this particular cookie recipe are the cocoa and the baking soda; judging from the comments above, though, it may be that the 3/4 c of brown sugar in the recipe adds more acid than the 1/4 c of cocoa.