Chemistry in Cooking

“Chefs, you have 30 minutes to make a meal from these 4 mystery ingredients.  Your time starts now”, Ted Allen says to a group of professional chefs as their timer begins.  Chopped, an enjoyable, albeit stress-inducing show on the Food Network, is a fascinating, real-life cooking experiment where chefs make dishes using mystery ingredients.  Although the entertainment factor is dependent on your interest in cooking and high-intensity competition, it is captivating  to watch food chemistry play out in real time.  This got me thinking about just how much science is a part of our daily lives in the kitchen.  Whether or not you make every meal at home, it is likely that you’ve had to cook at least once in your adult life.  Cooking can come with instructions, if you choose to follow a recipe, but how that recipe works and how it was formulated are questions you don’t typically stop to ask.  Here I highlight some beginners’ chemistry reactions that occur while cooking in the kitchen.

Acid and base chemistry is one of the first concepts taught in chemistry classes, and most of us have seen or even performed the erupting volcano experiment  that exemplifies this concept.  Typical cooking applications of acids are to either soften or tenderize tough cuts of steak, such as flank or skirt steak which can be marinated in an acid mixture.  Bases, on the other hand, can react with fats and can cause a “soapy” flavor if not carefully monitored.  In cooking, bases are used to counterbalance sour profiles of the food, while in baking they are used as leavening agents in cakes or cookies.

This is not the only type of reaction we can come across in the kitchen. Cooking food in a pan on high heat, or even moderate heat for an extended period, causes browning.   For protein-containing foods, the browning is due to the Maillard Reaction, which occurs when the proteins in a dish react with reducing sugar at high temperatures.  The ‘golden crust’ that is observed on chicken and steak is due to this reaction.  If no proteins are present then caramelization occurs, which is when  sugar breaks down in the presence of heat, causing dark coloring of the food.  Dextrinization occurs when heat is applied to starches which form sugars called dextrin.  Dextrin is brown which give food the ‘toasted’ color and flavor profile seen in toasted bread.  Sticking with the heat theme, protein denaturation occurs when weak bonds in  protein molecules break down when heat is applied,  turning it into single amino acid strands.  Protein denaturation is most commonly observed when cooking an egg and the egg white turns from clear to white.

Some other techniques in the cooking chemistry arsenal include fermentation, gluten formation, and combustion.  Fermentation, or the anaerobic breakdown of carbohydrates, is what creates beer, yogurt, kombucha and sauerkraut.  When making bread, for example, the air bubbles which are created during kneading allow for fermentation of the dough allowing it to rise and giving it an ‘airy’ look and feel.  On the topic of bread, gluten formation occurs when glutenin and gliadin are added to water and mixed.   Combustion is typically reserved for flashier cooking events and involves a fuel (such as alcohol), and a heat source in the form of a flame reaction, causing a heat transfer which can be observed as light.  Hibachi grills typically perform combustion experiments when putting on the onion volcano show for diners and baked Alaska’s are dishes which employ this technique as well.

Although chemistry is associated with a laboratory with fancy glass beakers, it occurs daily at home.  The reactions we observe, but may not know the names of, allow us to create the delectable flavors in our everyday foods whether it’s in a restaurant, around a campfire, or in our own kitchens.

Peer Editor: Savannah Muron