Science Can Explain Why Your Cookies Don't Come Out Looking Identical

Though the sweet itself is seemingly simple, a chocolate chip cookie recipe actually calls for a fair bit of complex cooking. The recipe involves creaming, sifting, and scraping — and that's all before your dough even begins to bake. If you do try your hand at making a homemade dough, when you're pulling a fresh batch of cookies from the oven, you might notice that a few have taken on a peculiar shape during the baking process. You could use a drinking glass to manipulate them back into a perfect spherical shape, a cookie hack suggested by TikTok user @whatsgabycookin.

However, it's possible that the reason your cookies turned out imperfect is chemical in nature, and not merely cosmetic. There are a lot of factors at play while a cookie is sitting in the oven. Examining the science behind how and why your cookies rise could help you avoid the mistakes that made your sweets lopsided in the first place.

A number of heat-induced scientific reactions take place within a baking tray of cookies, per WFAA. The butter that you incorporated into your cookie dough melts at 92 degrees Fahrenheit, and its water content evaporates into steam. The cookie flattens, but stops at 212 degrees Fahrenheit, when the steam boils off and the newly made air pockets solidify. Baking soda helps to introduce extra air. Then, at 310 degrees Fahrenheit, the Maillard reaction occurs.

According to Science of Cooking, the Maillard reaction takes place when a sugar and an amino acid come together and are heated. The Maillard reaction is the reason why your chocolate chip cookies brown slightly while baking. Science of Cooking also tells us that at around 320 degrees Fahrenheit, your cookie will caramelize, losing even more water and developing extra flavor as the sugar's structure is warped.

With all these processes taking place inside your cookie, it's no wonder that there are inconsistencies across the batch. Fortunately, there are a number of potential solutions.

NPR, citing University of California, Los Angeles food scientist Liz Roth-Johnson, explains that your cookie's width can vary wildly depending on the temperature of the butter you use. Melted butter will develop smaller air pockets, leaving your cookie wide and flat.

The thickness of your cookies is also affected by the degree to which you mix your ingredients, per Insider. Over-mixing dough is one of the most common baking mistakes. As you mix, you add air to the batter, and over-aerated cookies have a tendency to fall flat. Undermixing, on the other hand, could leave essential ingredients unincorporated and result in an unsuccessful bake. C&H Sugar tells us that it is also important to thoroughly scrape dough from the sides of your mixing bowl, in order to make sure that no ingredients are left stuck to the sides, where they would be rendered useless in the impending bake.