From the brains behind brains on, this is the moment of um.

Answering those questions that make you go, um, um, um, moment of um come. Moment of Um comes to you from APM Studios. I'm Sebastian Finch Fletcher and I'm a very famous chef.

Um.

I don't know if you know this, but I'm a really big deal in the food world.

Gordon Ramsey once called me, a guy I think I met once in an elevator.

And Julia Child, the Julia Child, once said of me, huh, never heard of him, but he's got a great name.

Thank you, Julia.

I do have a great name.

Anyway, I just opened a new restaurant called Don't Apple My Leg.

Get it?

Apple, my leg? It's a brilliant name dreamed up by a brilliant chef, me. And this new restaurant is truly groundbreaking. All the dishes are made of

apples and all the waiters tell jokes. They're appalling everyone's legs constantly.

It's hilarious. As a famous celebrity chef, my specialty is serving raw fruits and vegetables.

Don't get me wrong. These foods really pack a nutritional punch. Here's the problem, though.

When you slice up apples, they turn brown after a while. I can't be serving brown apple slices in my soon-to-be Michelin-starred restaurant.

Why do sliced apples turn brown anyway? Caleb and Luke want to know too.

My name is Caleb, and I'm Luke. We're from Princeton, New Jersey. Our question is, why do apples turn brown when we cut them?

So apples turn brown when you cut them up because they go through a process called oxidation.

My name is Lee Kelsits.

I'm an associate professor and endowed chair of environmental tree fruit physiology at Washington State University.

Some apples will oxidize really quickly. If you cut it open, it'll turn brown within a few minutes.

As the compounds in the apple interact with oxygen in the air, they'll turn brown.

...