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The Chemistry Behind a Chocolate Chip Cookie

You might have heard the phrase “baking is a science” a lot, but have you ever wondered what that science is? Well, read on for a delicious post on the chemistry of cookies with a bonus chocolate chip cookie recipe!

Baking cookies seems simple, especially if you cook ready-made cookie dough, but it's really a series of chemical reactions. If your cookies never turn out perfect, understanding the chemistry that is happening may improve your chances.

Chocolate Chip Cookie Recipe:

  • 3/4 cup granulated sugar (sucrose)

  • 3/4 cup brown sugar (caramelized sucrose)

  • 1 cup unsalted butter (a fat)

  • 1 large egg (consists of water, protein, fat, and emulsifier)

  • 1 teaspoon vanilla extract

  • 2-1/4 cups all-purpose flour (contains gluten)

  • 1 teaspoon baking soda (sodium bicarbonate, NaHCO3, which is a weak base)

  • 1/2 teaspoon salt (NaCl)

  • 2 cups semi-sweet chocolate chips/add-ins

Pre note: To achieve the best results, you may want to use room temperature ingredients. This helps the dry and wet ingredients mix into the recipe more evenly, creating a well-incorporated cookie dough. The butter (fat) in the recipe affects the texture of the cookies and browns them, which contributes to the flavor as well as color. If you use a different fat than butter, such as oil, affects the flavor of the cookies and also the texture since other fats have a different melting point from butter.

1. Preheat oven to 375 degrees Fahrenheit. It's important to preheat the oven, as this affects the thickness of the cookie, its texture, and how evenly it browns.

2. First, mix together the sugar, brown sugar, butter, vanilla, and eggs. This is to blend the “wet” part of the recipe and create a well incorporated dough. No chemical reaction occurs at this point. Mixing the sugars with the eggs dissolves some of the sugar in the water from the eggs, so the crystals won't be as large in the cookies. Brown sugar adds caramelized sugar flavor to the cookies and adds a nice shade of brown. You don't want to over-mix the ingredients because beating eggs for too long affects the peptide bonds in proteins, which can break and deform it’s nature. Vanilla Extract, also known as V. planifolia, is derived from plants. This means it is also vegan/vegetarian friendly!

3. Next, sift the dry ingredients (flour, baking soda, salt) into the wet mixture. The flour contains gluten, which holds together the cookie so it doesn’t become sticky and runny. Baking soda, when combined with any acid, will produce carbon dioxide gas and water. The carbon dioxide bubbles get trapped in the cookie and cause the cookie to rise. However, if you are like me and love cookies that are chewy on the edges and gooey in the middle, these won't rise as much. The secret savior is salt. It slows down the activity of baking soda, so the bubbles don't get too big and the cookie stays chewy and yummy!

                                 2NaHCO3 → Na2CO3 + H2O + CO2

4. Stir in the chocolate chips. The chocolate chips are flavoring and are pure chocolate, which comes from the cacao plant. If you don’t like chocolate, add in some m&ms or any other candy!

5. Drop about two tablespoons of the dough fairly spread apart onto an un-greased cookie sheet. The space between the cookies matters! If you put the cookies too close together, the interior of the cookie isn't don't by the time the bottom and edges brown. 

6. Bake the cookies for 10 to 12 minutes or until they are light golden brown. They should be cooked in less than 15 minutes. 

Aftermath: When you take the cookies out of the oven, the new water gases within the cookie contract. The chemical changes that occurred during baking help the cookie keep its shape. This is often why undercooked cookies (or other baked goods) fall within the center.

The chemistry doesn't end with baking. The environment affects cookies after they cooled. If the air is extremely dry, moisture from the cookies escapes, making them hard. In a humid or hot environment, cookies can absorb vapor, making them soft. For best results, keep the cookies in airtight containers so that no air can enter into the jar and harden the cookies. 

I hope you enjoyed this post on the science of baking cookies! The next time you decide to bake chocolate chip cookies, come back to this post to achieve the best, chewy, and science infused cookies!


BY: Wafa Akbar


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