The Chemistry Behind Cookies

Abstract

For our project we made cookies and found out why certain ingredients affect the cookies and how they affected it. We used a basic recipe for cookies and took out one ingredient at a time flour first, then unsalted butter ,then baking soda , and lastly eggs we found out that the flour makes it a dough, the butter makes it thinner and crispier, the eggs make it fluffier, and the baking soda causes a reaction twice to make it expand more.

Introduction

Learning chemistry can be as easy as pie, or even a piece of cake. Ever wonder what the chemistry behind cookies is? Each ingredient has its own special job to help turn itself and the other ingredients into a delicious treat. For example, baking soda helps the dough rise by releasing carbon dioxide, flour acts as a binder for all the wet ingredients, eggs help create structure and a chewy texture. There is a lot that goes on behind your cookies, thousands of chemical reactions are happening while your cookies are baking. Proteins are uncoiling, sugars are melting, salmonella is being killed, and even the aroma from your cookies is a chemical reaction.

Procedure

Preheat oven to 350 degrees. Line the cookie pan with parchment paper . Microwave ¼ cup of butter in a heatproof bowl for 15 seconds, being careful to just soften the butter. Next, add ¼ cup of brown sugar, 6 tsp of white granulated sugar, and ½ tsp of vanilla extract. Now, in a small bowl, whisk a large egg and pour one half into the mixture and stir until evenly mixed. Then in a large separate bowl whisk together ¾ cups of flour, ¼ tsp of baking soda and ¼ tsp of kosher salt. Lastly, pour the wet ingredients into the dry bowl and mix until the wet ingredients are fully absorbed. Now evenly scoop the cookie dough onto the pan that was prepared earlier and bake for 10-11 minutes. Repeat the recipe, removing one different ingredient for each time you bake the cookies.

When baking the batch without butter you may need to put in a small amount of water to help the dough stick together, do not worry the water will evaporate during the baking process. The batch without flour turned into a dark caramelized mess and the butter pooled around the pan because there was no flour there to absorb it. Also, when this batch was removed from the oven the dough was boiling because the sugar had reached its melting point. And the taste of these cookies was like burnt caramel.

The batch without eggs came out flat. They were crisp and crumbly. Eggs help give structure by bonding with the starch and protein from the flour. The cookies were crisp because the protein in eggs is what gives eggs their chewy texture. The batch without baking soda came out flat and crumbly, similar to the eggless batch, they were also extremely sweet.

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This batch was harder to mix, because there was less wet ingredients to help stick the dry ingredients together. So, a small amount of water had to be put into the dough as a substitute for the eggs. As a result, the finished product had bigger, more visible air holes. And the dough was squishy.

Discussion of Results

When you slide the pan into the oven, you're setting off a series of chemical reactions that transform one substance, dough, into another, cookies. When the dough reaches 92 degrees the butter inside melts causing the dough to start spreading out. Butter is an emulsion, or mixture of two substances that don't want to stay together, in this case, water and fat, along with some dairy solids that help hold them together. As the butter melts, its trapped water is released. And as the cookie gets hotter, the water expands into steam. It pushes against the dough from the inside, trying to escape through the cookie. Your eggs may have been home to salmonella bacteria. An estimated 142,000 Americans are infected this way each year. Though salmonella can live for weeks outside a living body and even survive freezing, 136 degrees is too hot for them. When your dough reaches that temperature, they die off.. At 144 degrees, changes begin in the proteins, which come mostly from the eggs in your dough. Eggs are composed of dozens of different kinds of proteins, each sensitive to a different temperature. In an egg fresh from the hen, these proteins look like coiled up balls of string. When they're exposed to heat energy, the protein strings unfold and get tangled up with their neighbors. This linked structure makes the runny egg nearly solid, giving substance to squishy dough. Water boils away at 212 degrees, so like mud baking in the sun, your cookie gets dried out and it stiffens. Cracks spread across its surface. The steam that was bubbling inside evaporates, leaving behind airy pockets that make the cookie light and flaky. Helping this along is your leavening agent, sodium bicarbonate, or baking soda. The sodium bicarbonate reacts with acids in the dough to create carbon dioxide gas, which makes airy pockets in your cookie.

Now, it's nearly ready for a refreshing dunk in a cool glass of milk. One of science's tastiest reactions occurs at 310 degrees. This is the temperature for Maillard reactions. Maillard reactions result when proteins and sugars break down and rearrange themselves, forming ring-like structures, which reflect light in a way that gives foods like Thanksgiving turkey and hamburgers their distinctive, rich brown color. As this reaction occurs, it produces a range of flavor and aroma compounds, which also react with each other, forming even more complex tastes and smells. Caramelization is the last reaction to take place inside your cookie. Caramelization is what happens when sugar molecules break down under high heat, forming the sweet, and slightly bitter flavor compounds that define caramel. Flour is important because it bonds to the other ingredients.

Future Expansion

If someone were to do this experiment in the future then it would be a good experiment to try a different recipe and see if the results are better or worse. We could test the recipes that are meant to have ingredients move and/or substituted.

After this experiment it is possible to use this experiment in many different ways such as eggless cookies, or another ingredient that someone is allergic to so that you can figure out how much that ingredient is important to the cookies and if there's a different ingredient to use instead

Conclusion

The batches did come out with different textures depending on which ingredients was removed from the recipe. But not all the ingredients made changes as drastic as we thought they would be. For example the eggless batch tasted normal and looked normal. The only thing that really changed was that they were very crispy.

Bibliography

1. https://www.npr.org/sections/thesalt/2013/12/03/248347009/cookie-baking-chemistry-how-to-engineer-your-perfect-sweet-treat
2. https://ed.ted.com/lessons/the-chemistry-of-cookies-stephanie-warren
3. https://www.fifteenspatulas.com/the-perfect-chocolate-chip-cookie/
4. https://www.seriouseats.com/2015/12/cookie-science-how-baking-soda-works.html
5. https://facty.com/network/how-to/how-to-make-ten-classic-cookies/?style=quick&utm_source=adwords&utm_medium=c-search&utm_term=%2Bcookie%20%2Brecipes&utm_campaign=FN-USA_-_Search_-_how_to_make_ten_classic_cookies_-_Desktop&gclid=CjwKCAiA_MPuBRB5EiwAHTTvMVy8jZoUrGj9Te8H1x2pl7uhrhzHyEuEBavbd2y-zdIpkCR8jCj5jhoCTXoQAvD_BwE
6. https://www.npr.org/sections/thesalt/2013/12/03/248347009/cookie-baking-chemistry-how-to-engineer-your-perfect-sweet-treat