Merry Christmas! I apologize for the lack of posts. Things are very hectic because I am finishing my Ph.D. and looking for jobs. Both tasks are very time consuming.
I would like to thank people who read my posts and send nice comments. I am glad to know that my ideas and explanations are having an impact in people’s understanding. Your kind notes inspire me to write more posts.
Happy 2008 to everyone!
-Dr. Dave
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In honor of Remy, the culinary genius from the recent Disney/Pixar movie Ratatouille, I will discuss the science behind cooking.
Cooking is one of my favorite forms of science because in the end, you can eat your experiment.
A great chef is both a scientist and an artist. They constantly experiment with different combinations of flavors and foods to create fantastic tasting meals. Do you remember the last time you had a really great pizza, or had a fantastic desert that knocked your socks off? What made it taste so good?
The science of heat
Cooking is the transfer of heat energy from some source to the food. In the kitchen there are three devices that are used to cook food: the stovetop, conventional oven, and microwave oven. Each of theses devices are designed around a different method of heat transfer.
The movement of heat is so important that there is a name for it: Thermodynamics. By understanding how heat moves, we can gain insight into our everyday world. It is responsible for the weather, car engines, your refrigerator, cooking, and a host of other things that you may not have even thought about.
Heat is transferred in three basic ways listed below:
Conduction is heat transfer through direct contact. When cooking on the stovetop, the heat from the flame or electric grill is applied directly to the frying pan. This means that only the flat surface of the pan is sufficiently hot enough to cook anything and we must flip and toss around the food to cook it properly.
It is important to note that most pans are made of metals, like copper, that conduct heat very efficiently and do not melt on the stovetop.
Convection is heat transfer through a fluid. The fluid can be liquid or gas and in the case of a convection oven, the fluid we care about is air.
A convection oven is a confined area that gets hot by flames or electric coils. The air inside is warmed to a desired temperature and, as a result, cooks the food from all directions. This method of heat transfer is responsible for pizzas, cakes, and other baked treats!
Keep in mind that convection ovens heat foods from the outside. The inside slowly heats up with time, and it is not uncommon to see food where the outside looks done, but the inside is uncooked. This is very important when preparing a Thanksgiving turkey, and there are special thermometers that measure the temperature of the food in the center of the turkey to show that it is properly cooked.
Radiation is the transfer of heat using electromagnetic radiation. A microwave oven uses very strong radio waves (a form of electromagnetic radiation), which are very weak and not hot. So how does it work?
Microwave ovens work by spinning water, fats, sugars and oils inside the food. This causes friction, which then heats the food and cooks it from the inside.
Please do not be confused by the word radiation or electromagnetic radiation. In science, these terms are very general and mean a lot of things. Radiation comes from many sources, some are beneficial and others are harmful. For example, solar radiation from the Sun is responsible for heating the Earth and the light we see is a form of electromagnetic radiation.
As you know, heat is very important in the cooking process. Now you have the basic knowledge of heat transfer.
Look at the world around you. Don’t be afraid to ask, “How does that work?” Be curious and seek help from people willing to help you (like me).
Let your curiosity guide you through this everyday world.
-Dr. Dave
