A very important topic for Penn State students is chocolate chip cookies.  We talk about where to get the best ones and occasionally argue about it (Redifer’s are decent, the ones in the back of Pollock are good, and West’s are legendary).  We debate whether to eat another one and complain that we are all going to get fat if we don’t cut back on our cookie intake.  Yet we are still delighted when our parents send us chocolate chip cookies.

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The chocolate chip cookie is a legend in and of itself.  According to the New Yorker, it was created by Ruth Wakefield in the late 1930s.  She ran a restaurant called Toll House and, on March 20, 1939, gave Nestle the right to use her recipe.  This is the recipe on the back of bags of Nestle chocolate chips, and it’s the one my mom usually uses.  The New Yorker says that there are many stories explaining how Wakefield invented the chocolate cookie, but “the more believable, if somewhat less enchanted, telling” is the explanation food writer Carolyn Wyman gives.  She believes that the new invention came from Wakefield’s hard work and talent.

After the discovery was shared with the world, the chocolate chip cookie-making business took off.  The New Yorker mentions Famous Amos, Chips Ahoy, Mrs. Fields, and David’s cookies as some of the new cookie businesses.  And somehow, none of these cookies tasted quite the same, even though they were all categorized as chocolate chip cookies.

There is a surprising amount of science that has been done concerning the cookie.  Although  most of the experiments that I found were not on scholarly websites given that it is not the most serious topic, many people have been interested in the topic and have experimented to find the perfect cookie.  There appear to be many different techniques to making different variations of the cookie.

A  website called bakepedia.com had heard “a lot of anecdotal evidence that leaving chocolate-chip cookie dough in the refrigerator for up to 48 hours will improve the cookies.”  So they decided to do an experiment to provide more substantial evidence to the anecdote.  They mixed one batch of dough and baked part of it after chilling it for 0 hours, 1 hour, 6 hours, 24 hours, 36 hours, and 48 hours.  I am assuming that by baking only one batch of dough, they were attempting to control the levels of variability.  They found that, while one hour did not make a noticeable difference, they started to notice a change in the results after six hours.  By the time they reached the 48-hour batch, the cookies were noticeably different.  Bakepedia believes that there is a mechanism behind this.  They say that the longer the dough sits, the more time the flour has to soak up the liquid.  Although this causes the dough to become drier, the flour itself is hydrated, so once the cookies are baked they are chewier.

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There are many other cookie “tricks,” according to a website called The Salt.  Apparently more flour makes cookies more gooey (I’m guessing this is for a similar reason as the one above- the flour soaks up liquid) and bread flour makes them more chewy.  If you add baking powder and baking soda, the cookies come out crispy with a soft inside.  For more tips, visit the site.

Now, I’m sure many people have heard before that baking is science; it’s like chemistry.  So what is the science behind the actual baking of the cookie?

The Salt provides an explanation for each aspect of the cookie.

When the dough begins to warm, the butter inside it melts.  The ball of dough begins to soften and lose its form, expanding into a circle.  The time of expansion will determine the diameter of the circle.

Mixed into the cookie dough is water and occasionally baking powder or soda.  As we know, heat turns water into steam, and steam rises.  This causes the cookie to rise as well.  And if there is baking powder or soda, it will create carbon dioxide gas which also contributes to the rise.  The holes that the gases leave as they escape the cookie help create the texture of the cookie.

The Serious Eats website explains that when the cookies reach a certain temperature, the egg proteins and starches become structured, helping to finalize the shape of the cookie.  The author of the Serious Eats’ article actually conducted experiments to find out what each of the ingredients did.  She baked the different batches without an ingredient to see what changed each time.  These experiments, though, had a high chance of variability since even when you bake the same recipe, dishes will continuously turn out to be different.

The final chemical reactions help affect the flavor of the cookie as well as its color.  When the sugar in the cookie caramelizes, it turns into a brown liquid that lends flavor and color to the cookie.  The other reaction is the Maillard reaction, which Food Science TV describes as the reaction of sugars with amino acids.  As they break down due to heat, the sugars and acids begin to bond, forming new compounds that give flavor and aroma to foods.

So.  Every time you eat a cookie, you’re actually eating a chemical reaction.  And when you’re following a recipe, you’re following the perfected instructions of experiments that were tested over and over again- and are still being tested as people search for the perfect chocolate chip cookie. There are so many ingredients and factors that go into making a cookie and so many ways to manipulate the outcomes.  In fact, my final conclusion is that chocolate cookies are way more complicated than I ever would have guessed.