What is cheese exactly? -Mark 11

Dear friends,

Cheese is delicious. At least, that’s this cat’s professional opinion. For the more scientific answer, I visited the cheese makers here at Washington State University.

Cheese is the fat and protein from milk, said my friend John Haugen who runs the WSU Creamery where they make Cougar Gold cheese.

At the creamery, students test milk from the dairy to make sure its fat and protein ratio is just right for cheese. They also heat up the milk to get rid of any bad bacteria—it’s a process called pasteurization. Not all bacteria are bad, though. In fact, some bacteria are really helpful for making foods, including yogurt, pickles, and cheese.

All cheese is made with a kind of lactic acid bacteria. These tiny little organisms are so small you would need to use a microscope to see them. They eat the sugar in the milk and make acid. The acid gives the cheese its tangy flavor.

There are even certain kinds of bacteria that are in charge of making the holes in Swiss cheese.

As Haugen explained how they add bacteria into the milk, I wondered how the liquid mix becomes a solid.

Haugen said that we need an enzyme, a protein that has a very special job to do. In cheese, enzymes work on protein in milk to break the bonds that keep it together. The protein opens up and sticks to other proteins around it to create a solid. If the enzyme does its job, the liquid will thicken, or coagulate.

“It’s almost looks like thick yogurt,” he said.

After that, the cheese makers will cut up the coagulated milk. When it starts looking a bit like cottage cheese, a machine pumps the mix onto a metal table.

This mix is partly made up of whey, which is mostly water. The other part of the mix is the soft, fresh curds. You can eat the cheese curds. They are tasty. Trust me. But they aren’t quite officially cheese yet.

First, the student cheese makers will pack the curds together into big loaves. They will flip the loaves over several times in a process called “cheddaring.”

If you wanted your cheese to be stringier, softer, crumblier, or harder, you might treat it a little differently. But at the creamery, Cougar Gold gets cheddared, chopped up, and salted to kill off some of the remaining bacteria and to keep it from liquefying.

The cheddaring process is actually named after the place where cheddar was first invented—Cheddar Gorge in England.

During the 12th century, people kept their cheese in caves. The temperature and humidity was just right for storing cheese.

At the WSU Creamery, cheese is also stored at just the right temperature, but inside tin cans.

“It’s almost like its own little cheese cave,” said Haugen. The cheese will stay in the can one full year before we eat it. Aging the cheese helps bring out the flavors.

After my visit to the creamery, I learned cheese is not just delicious. It’s milk, bacteria, enzymes, and salt. It’s science.

Sincerely,

Dr. Universe

•••

Why do volcanoes “die”? -Loretta, 11, Mexico

Dear Loretta,

Each volcano’s life is a little different. Many of them are born when big chunks of the Earth’s crust, or tectonic plates, collide or move away from each other. The moving plates force hot, liquid rock, or magma, to rise up from deep within the Earth.

When things get super hot and lot of pressure builds up in the magma chambers, volcanoes can erupt. Some volcanoes can spew ash and lava several miles into the sky. Others will slowly ooze out lava.

Just as each volcano is unique, so are the reasons they go extinct. Generally, though, if a volcano doesn’t have a source of magma, it won’t erupt.

That’s what I found out from my friend John Wolff, a geologist at Washington State University. To explore more about how volcanoes lose their magma, Wolff and I headed to the plains of southeast Idaho. There, the remains of really old volcanoes are buried underground.

Millions of years ago, we would have been able to see these volcanoes at the surface. They might have been spewing out lava and ash. But now, they no longer have their source of life.

If you are anything like me, you might be wondering what on Earth happens to the magma. Wolff is really curious about this, too.

He explained that volcanoes, and all of us, are riding on pieces of the Earth’s crust.

These pieces of crust move very slowly—just about as fast as our fingernails grow. They move over heat sources, zones of hot, upwelling rock from deep in the Earth’s interior. It melts the crust when it gets near the surface to fuel the volcano.

“It’s burning a hole in the plate,” he said. “Just like if you passed a plastic sheet over a candle flame.”

Eventually, when volcanoes have rafted away from the heat source, they falter and die.

As the Earth’s crust moved, slowly but surely, over millions of years, the magma that was under old volcanoes in southeast Idaho ended up in Wyoming—under a big super volcano.

Never having seen a super volcano before, I imagined a huge mountain erupting tons of lava. You can imagine my surprise when Wolff explained that this super volcano was actually Yellowstone National Park.

Millions of years ago, the Yellowstone super volcano erupted and collapsed. There is still magma under Yellowstone, but we don’t expect it to erupt anytime soon.

While a volcano may need to have magma to stay alive, there are still volcanoes that have a magma supply and can sleep for millions of years—and you thought us cats slept a lot.

Some scientists are really curious about how the landscape changes, both above the ground and below it. In fact, they ask questions that are a lot like yours, Loretta. Who knows, maybe one day you could help us investigate the lives of volcanoes.

Sincerely,

Dr. Universe

Which of these volcanoes would you most like to see?

•Mauna Loa in Hawaii

•Mt. St. Helens in Washington State

•Yellowstone Caldera (Yellowstone National Park)

•All of the above!

Vote in this week’s question, explore more topics or ask a question at https://askdruniverse.wsu.edu/.