Behind every flaky crust, moist crumb, sticky sauce, or charred crisp produced in your kitchen are fundamental chemical concepts and fascinating reactions. Every change in ingredients undergone during cooking is produced by molecules interacting with each other and chemical bonds forming or breaking. Basic chemistry can be applied to almost any process or dish. Using these concepts, I’ll go over the chemistry behind two of my favorite dishes perfect for a bright summer meal.
One of my favorite pasta recipes is this Pepperoni Pasta from the New York Times. The crispy pepperoni provides a savory crunch perfectly harmonized with bright lemon zest and sweet fennel. The cooking process illustrates a few important chemical reactions in cooking.
Boiling Pasta
Pasta is made mostly of protein and starch from flour and egg. When cooked in water above a certain temperature, the starch granules swell as they fill with water, softening the texture of the pasta. At the same time, gluten—which is formed in the dough-making process from the proteins gliadin and glutenin—is denatured by the heat. When proteins are denatured, their structure is unraveled as bonds are broken. Gluten then reforms into a web-like structure, holding the starch. Overcooking the pasta causes the starch granules to absorb too much water, leading to a mushy texture. Starch in the pasta also undergoes gelatinization during cooking: it comes out of the pasta and dissolves in the water. This is why your pasta might stick together unless it’s stirred. The dissolved starch is also why you should add a cup of the pasta water to your sauce. As starch granules take in more water, the sauce thickens. Pasta water acts as an emulsifier, surrounding fat molecules and allowing the sauce to better stick to the pasta.
Browning Meat
To make the sauce, I started by browning pepperoni in a pan with olive oil until crisp. The chemical reactions that occur transform the color, flavor, and texture of the pepperoni to provide a crunchy and flavorful bite. These changes in aroma and appearance signal nutrient availability and that food is thoroughly cooked and safe to eat. The Maillard Reaction is a series of chemical reactions that causes the browning of food. The first requirement is heat—higher than the 212℉ of boiling water, which is why boiling food doesn’t achieve the same brown color as roasting, frying, or grilling. Given heat and some time, the proteins and sugars in food react together in complex ways, rearranging the amino acids and simple sugars into bonds that reflect light to produce the brown color we perceive. The fat in the pepperoni also causes changes during cooking. Fat is made of long carbon chains which store more energy than water. When fat in the pepperoni absorbs heat and melts, it allows the pepperoni to cook at a higher temperature, promoting the Maillard Reaction and the evaporation of water. This dehydration process leads to a crispier texture. Heat and time causes reactions in different types and ratios of molecules, resulting in a flavorful, savory dish that’s nutritious and diverse in taste and texture.
Baking Banana Bread
The same concepts from cooking pasta apply to baking but with different results. To demonstrate this, I used up some bananas going past their prime by turning them into banana bread. I followed this Sweet Potato Banana Bread recipe to make an easy and nutritious snack or dessert.
While baking banana bread may seem like a completely different process with a different result, many of the same reactions occur. The Maillard Reaction is once again responsible for the golden crust. In banana bread, the ratio of proteins to sugars is significantly lower, so while the Maillard Reaction occurs, a process called caramelization also contributes flavor. Caramelization happens when sugars react with water through hydrolysis, giving a sweet and nutty caramel flavor. In banana bread, because there is more sugar than protein, caramelization has more of an effect on the flavor than the Maillard Reaction compared to when cooking meat. Read more about sweetness in this article about the chemistry of sugar in cooking.
#SpoonTip: Turn the bread halfway through baking to achieve an even golden crust and avoid burning half like I did.
Another concept relevant to baking banana bread is leavening. This banana bread batter contains baking soda and apple cider vinegar. When these ingredients react, they produce carbon dioxide gas. The gas forms bubbles in the bread and allows it to rise, giving it its fluffy texture. (Think second-grade science fair baking soda and vinegar volcanoes.) The protein denaturation from the egg and gluten from the flour provide structure for the bread, and starch absorption keeps the bread tender and moist.
Cooking is all about chemistry, which is all about the changes in the properties of matter. The ingredients in your kitchen undergo diverse reactions to become appetizing, aromatic, and flavorful, signifying their nutritional value. Hopefully, the reactions I’ve discussed in a few of my favorite recipes have encouraged you to learn about the fundamental chemistry concepts behind your favorite dishes!