Questions re: Baking Powder and Baking Soda

[Shel_B]

I'm pretty new to baking, and not at all knowledgeable about the science of the art and about how ingredients, like baking powder and baking soda, work together. Asking some of the more experienced folks here seems a reasonable thing to do.

What is the difference between double acting baking powder and single acting baking powder? Can they be used interchangeably? How might results differ when using one or the other? If a recipe calls for one and I use the other, will my result suffer?

How long can baking powder and baking soda last in an unopened container? What about a container that has been opened but has been stored covered? Can either be stored in the cupboard, or is a refrigerator a better choice?

If a recipe calls for the addition of plain milk as a liquid, and I use buttermilk or yogurt in its place, might I have to change the amount of baking powder or baking soda in the recipe?

Since both ingredients cause baked goods to rise, why would a recipe call for both baking powder and baking soda? If I added more of one or the other ingredient, how would the result be affected?

Well, that's enough questions for now. Thanks for any help, suggestions, or pointers.

[keychris]

I wouldn't store them in the fridge, as when you bring them out of the fridge, water from the air will condense on the cold powder, and it will get absorbed, your powder will eventually go gluggy.

From my understanding, bicarb soda is a single chemical (sodium bicarbonate) whereas baking soda is two, usually mixed in rice flour or some other flour - sodium bicarbonate and an acid component, tartaric acid (cream of tartar). Bicarb soda is a base, cream of tartar is an acid, they react with each other when combined in baking to produce CO2 and leaven the mixture.

Double action, iirc, refers to baking powders that have a third component, which reacts when heated to produce CO2 - ie, the regular reaction of acid + base will occur when the mixture is created, but then when you bake it, another reaction occurs and you get more leavening.

Joe Pastry has some good reads:

http://www.joepastry.com/2011/why-is-there-both-baking-powder-and-baking-soda-in-this-recipe/

http://www.joepastry.com/2011/the-first-american-baking-powder/

and a few more

[Bojana]

There is a great Harvard video from the Science and Cooking series that explains exactly that:

[DianaM]

I will do my best to answer your questions point by point below.

I'm pretty new to baking, and not at all knowledgeable about the science of the art and about how ingredients, like baking powder and baking soda, work together. Asking some of the more experienced folks here seems a reasonable thing to do.

What is the difference between double acting baking powder and single acting baking powder? Can they be used interchangeably? How might results differ when using one or the other? If a recipe calls for one and I use the other, will my result suffer?

How long can baking powder and baking soda last in an unopened container? What about a container that has been opened but has been stored covered? Can either be stored in the cupboard, or is a refrigerator a better choice?

If a recipe calls for the addition of plain milk as a liquid, and I use buttermilk or yogurt in its place, might I have to change the amount of baking powder or baking soda in the recipe?

Since both ingredients cause baked goods to rise, why would a recipe call for both baking powder and baking soda? If I added more of one or the other ingredient, how would the result be affected?

Well, that's enough questions for now. Thanks for any help, suggestions, or pointers.

Difference between double and single-acting: keychris has answered this. I'll just add this: single-acting means it's activated by acid at the mixing stage. Double-acting means it is BOTH acid-activated during mixing, as well as heat-activated during the baking stage. If the recipe calls for double-acting, I would not substitute single-acting. Double-acting is widely available though, I don't think you should have a problem purchasing this one. I myself don't keep single-acting around, I just find I get the best results with double-acting and use it in all my baked stuff.

Shelf-life: baking soda will last indefinitely in an unopened, or tightly closed container. Baking powder has a shelf-life of approximately one year from the day you open it. You can also test if it's still active this way: http://www.davidlebovitz.com/2011/11/how-to-tell-if-baking-powder-is-still-good/

Buy less of both BS and BP, so you don't have to store them for long. BS in the cupboard. If I bought lots of BP, I'll keep some in the cupboard for easy access, the rest can be kept in the freezer, and you use it to replenish your cupboard stock. Bring it to room temp before opening the bag, though, to avoid the condensation problems keychris was mentioning.

Substituting buttermilk or yogurt for milk in a recipe: yes, you most definitely will have to change the amount of BS/BP in the recipe. This is a tricky one, in my experience. The acid-base equilibrium is the crux in the leavening of cakes, and I myself have not yet learned how to do this in a consistently successful manner. It might help you to know this general rule of thumb: 1/2 teaspoon BS is neutralized by 1 cup fermented milk or 1 teaspoon of lemon juice or vinegar. (McGee, p.534, and Beranbaum p. 473) Perhaps more experienced bakers can help you with this one.

Why use both baking powder and baking soda: BP is basically an alkali combined with a dry acid, plus cornstarch. The leavening power of BP comes from the reaction of the base with the acid, when the solid acid comes into contact with water. If the recipe contains too much acid (ingredients like molasses or brown sugar, cocoa and chocolate, buttermilk, yogurt, sour cream), then the base in the BP is not enough to neutralize all the acid. And that is why you also need some baking soda in the recipe.

I hope this helps you. I learned all this from McGee's On Food and Cooking (see Chapter 10, p. 515 and onwards), and Beranbaum's Cake Bible (p. 419-445, 469-478). Both are excellent resources.