When I tell someone that I study the physics of food, they usually respond with a tilt of the head and the question, What does physics have to do with food?

Well, nothing says “Friday night” better than a warm, bubbly pizza, so let’s consider the options for a home-cooked pizza from a physics perspective to see how physics connects to our food system.

You might guess that eating a pizza made with homemade crust and fresh ingredients has less negative environmental impact than a frozen pizza. That’s true, as there is a dramatic reduction in the processing, packaging, refrigeration, and transportation energy, but that’s not where the discussion ends.

There are different energy costs associated with how the pizza is cooked—gas, electric, convection, or solar oven, for example. But what about skipping the oven completely? Heating an entire oven and its approximately 30 pounds of steel for one pizza isn’t the most energy-efficient option.

College students in my physics of energy-efficient cooking class enjoy performing a hands-on experiment comparing the energy of cooking oven-baked and range-top skillet pizzas. The oven method uses more than four times the energy of the range-top method.

The amount of energy it takes to make a skillet pizza varies with the skillet you choose. My most recent research uses infrared thermography to compare the thermodynamic properties of eight different skillet materials. It turns out that cast iron is an excellent choice for cooking a low-energy pizza. Cast iron’s relatively low thermal conductivity allows the energy from the burner to stay at the bottom of the skillet, close to the food, and its high thermal mass allows for cooking to continue after the burner is off. You can further reduce your environmental impact by considering your toppings. Pound for pound, beef is responsible for ten times more greenhouse gas emissions than a vegetable protein counterpart. My favorite toppings are caramelized onions, mushrooms, and black beans.

The bottom line: We have an enormous opportunity to reduce the energy costs and greenhouse gas emissions associated with our food. A sustainable food future requires that we think critically about our cooking and regain control of our food system. Doing so also improves our health and budgets, and gathering around a home-cooked meal is a fantastic way to improve your relationships with family and neighbors!

Here are two simple ways to get started:

1. Shop smart. When you have a recipe that calls for diced potatoes, skip the freezer section and grab them from the produce section or farmer’s market. In doing so, you’re reconnecting to the food system and becoming part of the sustainable food future.
2. Cook smart. Your kitchen is a science lab. Don’t be afraid to experiment with food preparation strategies. Did you know you can cook pasta passively? Simply turn off the burner after the water/pasta mixture comes to a boil and let the water complete the cooking as it slowly cools.

The physics of food is a rich field of study with fascinating, delicious, and practical applications. If you’d like learn more, check out my website at http://www.knowwattscooking.com. Happy cooking!

Skillet Pizza

by Carla Ramsdell, Know Watts Cooking
This is for an 8-inch pizza cooked in a 10-inch cast-iron skillet.
1. Bring skillet to medium heat.
2a. Sauté desired veggie toppings, such as onions, mushrooms, and black beans, on a cast-iron skillet. Remove the toppings and set aside, then wipe out any remaining scraps.
2b. While the veggies cook, make the dough (or make it earlier and let it rise for an hour before rolling out):

• Dissolve ½ teaspoon of yeast in ¼ cup of lukewarm water.
• Add ½ teaspoon salt and / cup flour.
• Turn out onto floured surface and knead dough until it stays together, adding more flour as necessary to avoid stickiness.
• Roll or press into an 8-inch round.

3. Heat the cast-iron skillet to medium high and coat it with a thin layer of canola oil.
4. Place the 8-inch dough round on the skillet and turn the burner down to medium low. Let the dough cook for a couple of minutes.
5. Spray the top (uncooked) side of the dough with oil and flip the dough over so the uncooked side is on the bottom.
6. Quickly top with sauce, veggies, and cheese.
7. Put a lid on the skillet, turn the burner off, and cook for 2–3 more minutes to allow the bottom to cook and the cheese to melt.
8. Remove from skillet, cut, and enjoy!