Chemistry plays a role in cooking your eggs

"Why do eggs get hard when you boil them?," asked David Appelbaum, 14, an eighth-grader at Aptakisic Junior High School in Buffalo Grove.

Cooking is basically a chemistry experiment. Everything is made up of atoms, and groups of atoms are molecules. Cooking means applying heat to food, and when you apply heat to the molecules in food, they change.

"There are molecules inside egg whites and yolks called proteins," said chemistry professor Andy Kidwell at Harper College in Palatine. "Proteins are combined amino acids and you need these proteins to make cells for biological functions." Amino acids drive the reactions that help the body with metabolism and nutrition.

The liquid insides of the egg change when heated, forcing the molecules to change. The runny white and yolk become solid.

"When you add heat, you force a reaction where you are reworking the structure and connectivity of the proteins by removing water molecules," Professor Kidwell said. This is called denaturing the proteins.

Food science is only one area of chemistry, Professor Kidwell said.

"Almost anything you can see and can't see can be understood from chemical principles," he said. "Once you start thinking about it, there are many things around you that come directly from chemical processes."

Professor Kidwell uses eggs in his chemistry experiments to show students how to measure density.

"It's called the floating egg experiment," Professor Kidwell said. "We use sodium chloride solutions to measure the density of eggs dropped in those solutions."

A knowledge of chemistry is useful in many careers, including plastics, the manufacture of oil, gas and ethanol, the pharmaceutical industry, medicine, agriculture, mechanics, nanotechnology and environmental science.