Kelly McSweeney

Sep 6th 2020

Breaking Down the Science of Baking


This Thanksgiving, whether you’re making savory dinner rolls or sweet apple pie, the success of your meal will depend on the science of baking. Baking is both an art and a science. Bakers can experiment with flavors and alternative ingredients, but most of your favorite Thanksgiving baked goods start with the same basic formula. As science enthusiasts, there’s no better way to celebrate Thanksgiving than to break down the chemical and molecular interactions behind our favorite desserts.


Flour provides the basic structure for everything from the crustiest French bread to the puffiest pastry. It’s made of starches and protein called gluten. When you mix flour and water together, the proteins combine to form an elastic web called a gluten network. This gluten web traps air bubbles, while the starch sets as it heats to add support to the structure, according to The Spruce Eats. Different recipes call for different types of flour because of the protein content. Bread flour, for example, has a higher protein content, which gives it a strong gluten network and sturdy structure. Cake flour has lower protein content, which produces a weaker gluten network and fluffier end product, according to kitchn.

While gluten networks are helpful for providing structure, too much gluten formation can give your baked goods a tough texture. Mixing dough helps these networks form, which is why we knead bread dough (to make it strong and stretchy) and avoid overmixing cakes, cookies and quick breads like banana breads.

Shortening ingredients such as butter, oils and fats help limit gluten formation, because fat repels the water that gluten networks require. When you cut butter into flour, for example, it coats the flour and repels the water-based ingredients that you’ll add next. This avoids activating too many proteins at once, shortening the gluten formation so that you end up with softer, more tender pastries.

According to the Spruce Eats, fat also helps make cake fluffy. When you cream sugar and butter, the mixing process creates small pockets of air where the sharp edges of the sugar crystals interact with the fat.


Water allows ingredients such as yeast or baking soda to do their jobs. It also hydrates gluten so that the dough can take shape. Eggs serve several purposes in baking, such as binding the other ingredients together and providing structure since they start as liquid but become more solid when they are heated. Some recipes call for separating the yolk from the white because they each have different properties.

The yolks are filled with nutrients and fat, which adds to the pastry’s flavor and texture. Yolks contain an emulsifier called lecithin that brings water-based liquids and oil together, even though they usually repel each other. This process helps mix the ingredients together so that they are distributed evenly throughout the batter. It’s important to set the oven to the correct temperature because yolk proteins unfold and gel together when heated. When whipped, the water and protein in egg whites incorporates air bubbles that make a foam to lift dough and give it a fluffy, delicate texture. When whipped egg whites are heated in an oven, the air inside them will expand, further rising the dough, according to kitchn.


Leavening, or making the dough rise, is an essential aspect of the science of baking. When liquid ingredients are heated in the oven, they emit some steam that helps lift the dough. Typically, though, a specific leavening ingredient such as yeast or baking soda will be added to baked goods. This is where you must measure ingredients as precise as a chemist measuring materials for a science experiment. Too much leavening agent will make the bubbles so big that they’ll pop and leave you with a flat baked good, according to The Spruce Eats. On the other hand, if you don’t add enough leavening agents, you’ll end up with a dense end product.

A single-celled fungus called yeast is the classic leavening ingredient. It is such an ancient pantry staple that in August 2019, scientists collected 4,500-year-old yeast from ancient Egyptian pottery. Smithsonian reports that the scientists used the ancient yeast to bake a loaf of bread.

Yeast works by absorbing sugar and excreting carbon dioxide gas, which makes the dough rise according to Fine Cooking. Yeast contributes to the bread’s flavor, because during the fermentation process, yeast breaks down large starch molecules into smaller, flavorful simple sugars. Yeast helps develop the gluten network and strengthen the dough. When yeast releases gas into the dough, protein and water molecules are pushed together, which, just like kneading the dough, gives them another opportunity to form gluten.

While yeast requires patience, baking powder works instantly. Baking powder contains a dry acid and baking soda, which is also known as sodium bicarbonate (NaHCO3). According to ThoughtCo., baking soda (a salt) reacts with acidic ingredients and heat, which creates carbon dioxide as a byproduct. As soon as baking soda touches a water-based ingredient (milk, eggs, etc.), a chemical reaction occurs and gas bubbles start to release. This is why it’s important to avoid overmixing or leaving the batter out of the oven for too long.

When you bite into your Thanksgiving baked goods, think about the chemical and molecular interactions that make them so delicious. The aroma, color, flavor and texture all start at the molecular level. Recipes should be followed in order, just like you would follow the procedure of a science experiment. If you skip steps or go out of order, you’ll miss out on essential chemical reactions. This could leave you with deflated bread or dense muffins. A perfectly browned pie crust doesn’t happen by luck — it’s the science of baking.