Chemistry of Cooking

Chemical Reactions in Baking 

After all this research, it still did not explain why cake batter rises and stays risen once it is cooked and cools back down.  It would seem that the vibrational energy of the heat would slow down as it cooled and the cake would flatten.  How did it stay expanded?  After much investigation, the information was revealed. The answer was…a chemical reaction occurs.  This was the piece of information that I had been missing to complete this research puzzle.  It was not just applying heat to a state of matter; there had to be a chemical reaction.  So, why does cake batter rise and hold its shape?  It is because of the molecules and how they interact with each other…scientific magic.  Now, there is a big difference between making the cake from scratch and using a boxed cake mix. It is much simpler and cheaper to pick up a boxed cake mix but the scholars identify more of the ingredients if you make it from scratch.  The magic of cake’s chemistry will be explained from the perspective of making it from scratch.  

Let’s begin with the flour.  The flour you chose to use makes an impact on what you are creating.  You need cake flour if you are making a fluffy cake from scratch.  However, if you are making a pie crust then you use all-purpose flour.  The protein count in the cake flour is lower which provides a lighter texture and the all purpose flour has a higher count which creates a more dense texture.   The proteins in flour are gliadin and gluten.  These proteins are made up of amino acids that when mixed with sugar will later create the Maillard reaction when they are exposed to heat.  The Maillard reaction is the source of browning and heightened flavor of the cake.¹³ Once moisture is added to flour it allows these two proteins to intertwine.  This process creates a webbing of proteins which with another ingredient of the flour creates the structure.  What is this additional ingredient in flour besides those vital proteins?  It is starch.  “Starches are made up of two compounds, amylase and amylopectin”.¹⁴ Basically, they assist in thickening a mixture.  They can be used to gelatinize a mixture such as gravy or meringue, as well.  This one ingredient, cake flour, is primed and ready to create this magic.  It awaits vital ingredients to activate its chemistry.     

Next, we add in the baking powder which is the main ingredient to creating baking magic.  Baking powder and soda are responsible for creating carbon dioxide in the mixture.  This is vital because the carbon dioxide is what creates the bubbles that give cake its light and fluffy texture.  If you forget to add this to your mix, then you will have a hard brick-like cake.  Please, note that baking powder and baking soda are different ingredients.  Baking soda requires acidic ingredients like buttermilk or lemon juice to active the chemical reaction.  If your recipe does not have an acidic ingredient then the baking soda will never do its magic.  Baking powder, however, has acidic chemicals added into the mix that allows it to complete its magic.  Double-acting baking powder has two levels of reactions.  One, when it is mixed with wet ingredients, and another, when it is introduced to heat.  Finally, we mix in the salt to this dry mixture of ingredients.  Salt assists in masking bitterness and enhancing flavors.  There are flavor nuances that our senses would never register if the salt molecule did not bind with them to allow them to be experienced.  It is extraordinary how the simplest molecule can make such a huge difference in a mixture!

Now, it is time to discuss the wet ingredients.  The dry ingredients are left in their own container and a new container is used for wet ingredients.  The sugar, which is sucrose, is the first ingredient to be measured.  Sugar’s role in cake is twofold. First, it sweetens the mixture and second it works with the amino acids to achieve the Maillard reaction.  Fat is the first ingredient to mix with the sugar.  This is called creaming the sugar.  The fat in a cake recipe is the butter or shortening.  Also, it needs to be room temperature instead of chilled.  Chilled butter is for recipes such as pie crusts.  Temperature plays an important role in how fat mixes with other ingredients.  Chilled butter coats other ingredients while room temperature butter mixes with other ingredients.  Promptly begin mixing the butter into the sugar with a whisk.  This process will continue until the two ingredients cannot be distinguished separately.  The process of creaming the sugar with butter traps the air into the mixture.  The more air bubbles that are in the cake the less the result will be like a rock. 

Next, the eggs are added into the mixture one at a time.  The eggs’ role is to bind the ingredients together and assist in trapping the air into the cake’s structure.  Egg whites can become mechanically leavened if they are whisked and air is trapped within the denatured proteins.  This applies to recipes such as a meringue pie not to a cake.  These wet ingredients are whisked until all are evenly mixed.  Last, the milk is added.  Milk provides moisture to the cake as well as assisting the flour proteins in forming their crosslinks. 

Finally, it is time to mix everything together.  The dry ingredients are slowly mixed into the wet ingredients.  This allows all the ingredients to be saturated and evenly mixed.  The baking powder is producing carbon dioxide.  The flour, sugar, and eggs are trapping the gases, and the structure is being strengthened.  If you do not mix the ingredients correctly, then the mixture is doomed.  If you do not mix it enough then it cannot form the bonds needed to strengthen the structure to trap the gases.  However, if you over-mix it then the bonds that were formed become broken.  If the recipe calls for 50-70 strokes then 30 or 100 strokes is not going to create an ideal cake.  Also, it states that an electric beater can be used but you must pay close attention to the speed and length of time.   Pour the batter into the appropriate container and apply the required heat.  Cakes can successfully be baked in all three of the listed forms of heat.  The baking powder will produce more carbon dioxide causing the cake to rise.  The bonds formed will maintain the structure as the cake rises.  The sugar and amino acids cause the Maillard reaction and the cake browns as the flavor heightens.  The magic of chemistry is occurring and your delicious potion will soon be ready to eat.