At-home STEM Activities: Kitchen Chemistry—Crazy Cakes
In a blog post last week, we explored the chemical reaction of decomposition by making honeycomb candy. The cause of the decomposition was the application of heat—so this is also an endothermic reaction.
An endothermic reaction is the absorption of energy, usually heat, that changes the chemical structure of a compound. One example of an endothermic reaction is cooking! In a recipe, how each ingredient reacts to heat affects the final product.
Let’s see what certain ingredients in a cupcake contribute to the baked good by omitting them!
Crazy Cakes
For this activity, we’ll make the following recipe for a single cupcake 4 times—once following the recipe, once omitting the egg white, once omitting the butter, and one omitting the baking powder. The cupcake that we follow the recipe for is our control.
Recipe adapted from How Sweet Eats.
Ingredients:
1 Tablespoon egg white
1 Tablespoon sugar
1 Tablespoon butter, melted
1/2 teaspoon vanilla extract
2 1/4 teaspoon milk (or milk alternative, we’re using oat milk)
2 Tablespoon all-purpose flour
Generous 1/8 teaspoon baking powder
Pinch of salt
Materials:
Cupcake pan
Cupcake liners or non-stick cooking spray
Small mixing bowl
Measuring spoons
Whisk
Food coloring
Instructions:
1. Preheat oven to 350°F. Place cupcake liners in or spray with non-stick cooking spray each corner of a cupcake pan.
2. In the small mixing bowl, whisk together the egg white and sugar until combined and a little foamy. Add in the vanilla and melted butter, stirring until combined.
egg white and sugar
whisk until a little foamy
add vanilla and butter
3. Add flour, baking powder, and salt and mix until smooth. Stir in the milk.
Add flour, baking powder, and salt
mix until smooth
Stir in milk
4. Add one drop of food coloring to the batter. This will help identify which cupcake is which after we bake them. We’ll dye the cupcakes as shown below.
5. Repeat the recipe three more times, once without egg white, once without butter, and once without baking powder.
6. Bake at 350°F for 10-12 minutes, or until the cupcakes are set. Let cool completely.
Now that our cupcakes are done, let’s be scientists and see our outcomes!
control
no eggs
no butter
no baking soda
Observe each cupcake:
How does each cupcake look compared to the control cupcake?
How does each cupcake smell compared to the control?
How does each cupcake taste compared to the control?
What are the textures like of each cupcake compared to the control?
After making your observations, scroll down to see what each ingredient we omitted contributes to the cupcake.
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Egg whites:
Egg whites are 90% water, so when they’re cooked inside a cake, they cause steam, which helps give the cake rise. The other 10% of an egg white is protein, which gives structure to a cake.
In the cupcake without any egg whites, you may have found it to be a flatter, more crumbly cake.
Butter:
Butter is a fat, and fats add moisture, flavor, and tenderness to a cake.
In the cupcake without any butter, you may have found it to be a drier, tougher, less flavorful cake.
Baking powder:
Baking powder is a combination of baking soda and cornstarch, so when it is heated, it decomposes and releases carbon dioxide (just like in honeycomb candy). The gas bubbles within the batter, cause little pockets of air within the cake and allowing it to rise.
In the cupcake without any baking powder, you may have found it to be a flatter, denser cake.
