The Science of Cupcakes

I have been in a bit of a baking mood lately, and after watching a couple episodes of DC Cupcakes, I decided to do another molecular gastronomy post. So today, we are going to learn about substitutions in baking. Since this is everydaybiochemistry, why are not just going to learn about the possible substitutions. We are going to learn WHY and HOW they work. For example, why can you substitute vinegar for eggs in a cupcake recipe?

So to start out, let’s look at a basic chocolate cupcake recipe:

  • 13 cups flour
  • ¼ teaspoon baking soda
  • 2 teaspoons baking powder
  • ¾ cup unsweetened cocoa powder
  • 1 dash salt
  • 3 tablespoons softened butter
  • 1 ½ cups sugar
  • 2 eggs, beaten
  • 1 teaspoon vanilla
  • ¾ cup milk
  1. Heat oven to 350°F.
  2. Put cupcake liner in muffin tin OR grease very well muffin tin.
  3. sift flour, baking powder, baking soda, cocoa and salt.
  4. The in another bowl beat together the butter and sugar and then add the eggs beating very well then mix in the vanilla.
  5. Add the flour mixture alternately with the milk to the sugar and be sure to beat well each time.
  6. Spoon batter into the muffin cups 2/3 full.
  7. Bake for 15 to 17 minutes oven, or until a toothpick inserted into the cake comes out clean.
  8. It really depends on how full you fill the muffin tin to decide on the yield. If you want really domed cupcakes fill them almost full.
Now let’s look at some substitutions:
Flour: We’re not going to screw with this one, as I can’t find any substitutions for flour on the internet. You can, however, make flourless chocolate cupcakes. It looks like you remove the flour, baking powder, baking soda, and milk. And add a ton more chocolate 🙂
Baking soda: Baking soda is commonly used as a leavening agent. Also known as sodium bicarbonate, it is alkaline and also used to balance out acidic ingredients, such as vinegar, citrus juice, sour cream, chocolate, etc.). In the case of our cupcakes, my bet is that it balances the cocoa powder, which is acidic. Since the recipe we are working with also includes baking powder, I think that the baking soda is being used less as a leavening agent and more as a balance to acidic ingredients. Since there is no vinegar in this recipe, no volcano.

While most sites say that baking soda can be replaced with baking powder, I do not think that would be the case for our cupcakes. Baking powder, though also a leavening agent, has a neutral pH and cannot balance the acidity of the cocoa powder. According to this site, it does alter the taste much if you do not balance the acidity of cocoa powder. In conclusion, you probably do not need to substitute baking soda with anything when baking chocolate cupcakes. Another option would be to use alkalized, or Dutch cocoa powder.

Baking powder: Baking powder is a commonly used leavening agent composed of baking soda, cream of tartar, and starch. The cream of tarter is acidic, which counteracts the basic baking soda. Starch acts as a drying agent. In a recipe such as our chocolate cupcakes which calls for both baking soda and baking powder, the baking powder is likely the main leavening agent. Substituting baking powder is pretty easy, as long as you have baking soda and cream of tartar. The basic recipe is 2 parts cream of tartar to 1 part baking soda. No starch is needed if you are immediately using your homemade baking powder. Other recipes  for baking powder use alternative acidic ingredients such as buttermilk or yogurt. TLC has a great post about baking powder and how it works. Baking powder does not react with vinegar to create carbon dioxide, as is the case for baking soda. Instead, the baking soda in baking powder reacts with the cream of tartar to produce carbon dioxide.

NaHCO3 + KHC4H4O6 —-> KNaC4H4O6 + H2O + CO2

NaHCO3 + KHC4H4O6 —-> KNaC4H4O6 + H2O + CO2

Most baking powder is double-acting. This means that some bubbles of CO2 are produced when the baking powder gets wet, and the rest of the bubbles are produced when the baking powder gets hot in the oven. One last note about baking powder: the reason why recipes tell you to sift or whisk in the baking powder (which I NEVER do) is to prevent big holes caused by carbon dioxide bubbles.

Unsweetened cocoa powder: If you don’t have unsweetened cocoa powder, you can use Dutch cocoa powder. Of course, then you would not need the baking soda either to balance the cocoa powder, since the Dutch cocoa powder is neutral! Another suggested substitution is unsweetened chocolate. When using unsweetened chocolate, the fat in the recipe should be reduced by one tablespoon. “Why is that?” you may ask. I am beginning to realize that baking is all about balance.

Unsweetened chocolate, or baking chocolate, is made of chocolate liquor plus some type of fat, which makes the chocolate solid. Therefore, you do not need as much fat in your other ingredients. For our cupcakes, we could reduce the butter.

If you don’t want to use any type of chocolate in your substitution, there are some other options. Some healthy chocolate substitutes include carob, chocolate sapote (AKA black persimmon), and acai berry.

Chocolate Sapote

Salt: According to The Cake Bible, the function of salt is to accentuate or heighten flavor. Without salt, the cupcakes would have a “flat” taste. When looking up the use of salt in baking, I found this interesting article about the obstacles bakers face in trying to make healthier, low-sodium sweets. Salt substitutes are often used to reduce the amount of salt while maintaining flavor in food. While normal salt is sodium chloride, salt substitutes are usually a mix of potassium chloride and sodium chloride. Be careful, however, when using salt substitutes. Certain diseases and drugs reduce the body’s ability to excrete potassium. If you have this condition, eating potassium chloride could lead to hyperkalemia = not good.

Butter: Oh, butter. You make the world go round. According to In the Sweet Kitchen, butter, a solid fat, acts as a leavener when creamed with sugar. The granular sugar traps air as it is creamed into the soft butter. When the batter is heated, these bubbles expand, causing the cupcake to rise. With this in mind, it is easy to see why oil as a butter substitute could be a problem, as it will not trap air like the more solid butter. Second, oil is 100% fat while butter only contains 80% fat. When oil is being used to replace butter, less should be used. So fat is the ingredient that we really care about. Other sources of fat include shortening and lard. Another explanation that I have found for using fat in baking cakes and cupcakes is to prevent gluten from forming a network. When gluten forms this network, the cupcake can get tough or chewy. How this process actually works, I am uncertain, as I could not find good primary sources on the topic. There are some other alternatives to butter that are healthier, such as applesauce or any other type of pureed fruit.

Sugar: As mentioned previously, sugar assists butter to leaven the cake batter. Because of this, fine grained sugars are not recommended for baking cupcakes. Another nice thing about sugar is that it is hygroscopic–that is, it absorbs water. Because of this property, sugar prevents baked goods from drying out. Possible substitutions include agave nectar, Splenda, honey, maple syrup, and brown rice syrup. Agave sugars are about 11/2 times sweeter than normal sugar, so that should be taken into account. Cupcakes baked with honey will probably be more dense, with a higher moisture content, and may brown faster. When replacing sugar with a liquid sweetener, you may need to reduce the other liquids in your batter. Many baking websites that I have visited do not recommend artificial sweeteners, as they do not contribute the same amount of tenderness, moisture, or browning as real sugars. This is a great post explaining what type of sugar substitutes work well, and which don’t, when baking cupcakes.
Eggs: Egg whites act as a drying and leavening agent, while the yolk is an emulsifier. Vinegar and baking soda may replace eggs in cupcake batter, as the reaction mimics the leavening that the eggs provide. So NOW we can have our volcano!
Silken tofu, banana, and flax seed are commonly found substitutions. I cannot find much more detail on why eggs are used in cupcakes, or how the egg white acts as a leavening agent.
Vanilla: It appears that vanilla is only here to add flavoring. So substitute it with any extract you want (within reason)!
Milk: The primary function of milk in our cupcakes is to act as a liquid to lubricate all the dry ingredients and bind them together, along with the egg. Because of this, soy milk and other non-dairy “milks” can certainly be used. I bet even water would work.
So there you have it! The how and why behind all the ingredients in chocolate cupcakes. I am slightly tempted to make a batch of normal cupcakes and a batch of cupcakes with every single ingredient replaced…I’ll let you know the results if I do!

Author: ilovebraaains

I am a neuroscientist using zebrafish to study mechanisms of neuroregeneration.

2 thoughts on “The Science of Cupcakes”

  1. Substituting gluten-free flours would be an interesting topic but probably is a science in itself!

    The butter/oil thing is really cool! I always wondered what the deal was with that.

    I know that overmixing causes gluten networks to form. This is great if you’re making bread (that’s why all that kneading is necessary) but not so great for things like cupcakes and pancakes.

    What about using only egg whites and leaving out the yolks? I know a lot of people do this because it’s “healthier” but does that affect the final product?

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