What makes popcorn pop?

Popcorn is a special type of corn. Of the four types of corn, popcorn is the only one that can pop. It is different from other types of corn in that its hull, or outside covering, is just the right thickness to allow it to burst open.

Each kernel of popcorn contains a small drop of water stored inside a circle of starch. The starch is surrounded by the hard hull. The hull does not allow water in or out of the kernel. When you heat popcorn in the microwave, the drop of water in the kernel starts to heat up too. Once the water gets hot enough, it changes into steam inside the kernel. The steam makes the starch heat up and expand. Once the starch has expanded to the hull, it continues to push against it until the hull explodes. The starch rapidly cools when it comes into contact with air, creating the familiar white puff that you eat. The kernel swells to 40 to 50 times its original size.

Why does Swiss cheese have holes in it?

To make cheese from milk, the milk is slowly exchanged with bacteria. The bacteria makes lactic acid, which is essential to the production of cheese. Different types of cheeses are made using different bacteria, which is responsible for the different flavors.

Swiss cheese is made by adding a certain bacteria to milk after it has been warmed. The bacteria forms curds in the milk, which are pressed into heavy molds forming a cheese wheel. The Swiss cheese is densely packed with a very thick rind. As the Swiss cheese ages the bacteria inside continues to eat away at the cheese. The bacteria “breathes” out carbon dioxide gas. Since the rind is so thick, the carbon dioxide cannot escape and makes the holes for which Swiss cheese is known.