The Chemistry of the Perfect Brownie

It’s the night before Valentine’s Day and you realize you don’t have anything prepared for that special someone. You make haste to the kitchen in hopes to find something to make for that special someone. You stumble upon ingredients to make brownies, but you wonder whether it should be cakey or gooey. Nevertheless, you push on and try to find recipes to suit your special someone’s taste. Now here you are, reading this article. We’ve whipped up history bits and chemistry tips just for you.

  • Brownies date back to 1893 when Bertha Palmer requested Joseph Seyl to make a dessert that wasn’t messy to eat. And after a few mentions from cookbooks and the Kansas City Journal, it spread all around the world.
  • There are two types of brownies: cakey and gooey.
  • Cakey brownies are fluffy and crumbly and contain a higher flour ratio over oil.
  • Gooey brownies are soft and slightly sticky and have a higher oil/fat content in them.
  • Leavening agents are agents that cause your batter to expand and release gas in a form of steam. Example of organic leavening agents are eggs and yeast while chemical leavening agents are baking powder and baking soda.
  • The Maillard reaction occurs at 125 Celsius (257 Fahrenheit) which breaks down amino acids and rearrange them to ring-shaped compounds responsible for browning your food.
  • Caramelization is a similar process but the pyrolysis of sugar, which means sugar is being heated without the presence of oxygen and  broken down which releases steam.
  • You can either use chocolate or cocoa powder for your brownies just make sure to adjust the fat content for gooey brownies or flour content for cakey brownies. 

So, how did the brownie we all know and love come to be? This delightful treat dates back to 1893 at Palmer House Hotel when Bertha Palmer, an American businesswoman, philanthropist, and socialite, wanted to create a dessert that would be easy to transport and convenient  to eat. At the time, she was head of the Board of Lady Managers for the 1893 World’s Columbian Exposition and ordered Joseph Seyl, the head chef of the Palmer House, to create this treat. But why is it that the chef, who created the brownie, isn’t the one given credit for his work? Well, Seyl preferred to be at the back of the house and give all the credit to his employers, the Palmers. Even after Seyl’s creation, the first ever mention of the brownie was in Fanny Farmer’s cookbook “The Boston Cooking School Cookbook” in 1896. However, the recipe didn’t have any chocolate at all; rather it contained molasses. Then Sears and Roebuck published a catalog in 1897 and later on in an issue from 1898 of the Kansas City Journal advertised chocolate brownie from a local bakery–a brownie with chocolate in it! From there, it spread all around America and the world.

Cakey vs. gooey

Brownies are divided into two categories: cakey and gooey. Gooey brownies tend to be slightly sticky and soft, while cakey brownies are fluffy and crumbly. When making fudgy brownies you would use either more oil to increase fat content to give its fudgy texture or more chocolate. Both are effective because chocolate actually contains oil which is a factor in its fudgy texture. While cakey brownies have a higher flour ratio, decreasing the amount of oil content in your recipe would give you a cakey brownie. 

Baking Brownies

Now, the magical process of baking brownies. You first preheat your oven to approximately 180 degrees Celsius (or 356 degrees Fahrenheit). Then, cream or melt your butter and sugar together. For cakey brownies, cream the two ingredients together. For gooey brownies you have to melt the butter and sugar together (and chocolate if you will use it). Afterwards, add in your other dry ingredients, sift them into the bowl, and mix them all together until well combined. An optional step is to add in your mix-in, whether it be more chocolate or nuts, even fruits if you like. Then pop it in the oven for 25 to 30 minutes. After it is baked, let it cool.

It’s already obvious what happens in the oven—the brownie rises and the liquid batter becomes the gooey or cakey brownie you’ve been waiting for. Fun fact: there are chemical reactions that happen when we bake a brownie, even as we make the brownie itself. Let’s break down the chemistry.

Leavening Agents

Anything that causes your batter to expand and release gas is called a leavening agent. Eggs and yeast, which are used in making brownies are an example of natural leavening agents, while baking powder and baking soda are chemical leavening agents. These agents are used to help shape your favorite treats, like cakes, breads, and even brownies. 

Maillard Reaction

This reaction occurs in almost all foods as long as heat is being introduced to the food, specifically at the temperature of 125 degrees Celsius (257 degrees Fahrenheit). This non-enzymatic reaction: a reaction that doesn’t involve enzymes, breaks down sugars and proteins and rearranges them to ring shaped compounds which darken the surface of the brownie. Though it may not be obvious due to the batter being brown, you can see the difference more on steaks or lighter colored batters. Thus, this contributes to the toasted flavor and the fragrant aroma coming from food.


If you’ve made leche flan, then you’ve seen first hand the caramelization of sugar. Though it may not be noticeable in cakes, caramelization happens when you bake cakes or anything you’ve added sugar to. Caramelization normally occurs at 180 Celsius (356 Fahrenheit) and is the last reaction to occur during the baking process. When high heat is added to sugar, the molecules of sugar break down and release water which comes out as steam–also giving a hint of flavor. While caramelization is the pyrolysis (heating of an organic material with the absence of oxygen) of certain sugars, the Maillard reaction involves the rearrangement of amino acids. 

Cocoa powder vs. chocolate… or both?

Last but not the least, cocoa powder or chocolate? Maybe even both? As mentioned earlier, chocolate contains more fat while cocoa powder has less fat. Meaning, this wouldn’t require you to use more flour. Since chocolate would give moisture to your brownie, you need more flour to balance it out as no one wants a very moist brownie. Though the quality of cocoa powder may affect the taste of your brownie, the taste you’d get in the final product will be worth it. You may even use cocoa powder for gooey brownies, but you need to make sure you add more fat to get a higher fat content to get the gooey texture you want.

Behold, the brownie you’ve worked hard on is done! Courtesy of your amazing baking skills and an array of chemical reactions, you have created such a decadent treat. Whether you prefer a cakey or gooey brownie, you will certainly see the different chemical reactions unfold. Through the leavening agent that allows your brownie to expand, the Maillard reactions that cooks your brownie, and caramelization that gives it flavor and toastiness, this delicious treat should put a smile on that special someone’s face. Thanks to the delicious ingredients and love that it was made with. 



Beal, J. (2021, December 13). The chemistry of baking brownies. LEAFtv. 

Colby, T. (2018, August 31). Taste the Palmer House brownies for a bit of Chicago history. Forbes. 

Chemistry on Tumblr. (n.d.). Relating it back to chemistry: Baking brownies. 

Do You Want Science With That? (2014, April 22). Fudgey, cakey or chewy? The science of brownie baking. 

Geschenke2015. (2022, August 27). The birth of the brownie. Dannwoellertthefoodetymologist. 

Gillespie, C. (2019, March 2). Chemical reactions involved in baking a cake. Sciencing. 

Jampel, S. (2020, March 10). Cocoa Powder is the Secret to Superior Brownies. Bon Appetit. 

Kitchen Aid team. (n.d.) Types of leavening agents in baking. Kitchen Aid. 

Scienchef. (2022, July 26). The science of brownies – Exploring cakey vs. gooey. FoodCrumbles. 

USDA ARS. (n.d.). What is Pyrolysis?

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