Hi there! It's snack time here at the Fort,

so Squeaks and I are taking a quick  break from our busy day to eat.

[Squeaks squeaks.]

Oh, I brought something new  for a snack today, Squeaks.

I've brought some hard-boiled eggs.

I can crunch up the shell a bit,  then peel it off with my hands…

and then a little sprinkle  of salt for flavor, and yum!

[Squeaks squeaks]

Oh, that's true, Squeaks!

Hard-boiled eggs are quite a  bit different from raw ones.

They might look the same on  the outside, but boiling an egg

changes what we find inside the shell.

When you crack open a raw egg,  there's a clear, goopy, liquid part,

called the egg white, and a  smaller circle of yellow liquid,

called the yolk.

But take a look at my hard-boiled egg.

What do you notice about it?

[Squeaks squeaks]

Oh yeah, the egg is solid!

The egg white has turned white and firmed  up into the shape of, well, an egg.

And inside of it, we can  see that the yolk has become

a solid, yellow circle, with  a kind of crumbly texture.

[Squeaks squeaks]

Well, Squeaks, the inside of this  egg became solid when I boiled it.

Cooking food in different ways, like boiling,

can change a lot about them.

When you boil food, you're  heating that food up a lot

by sticking it into really hot water.

And that can do some really  strange things to food:

carrots get softer, butter  and ice cream melt, and eggs,

well, they get harder and tougher.

Why do you think that is, Squeaks?

[Squeaks squeaks]

Yeah, it is a tough question.

How about this: what do we know about eggs?

[Squeaks squeaks]

They are really yummy!

And they're also really good  for us. Do you remember why?

[Squeaks squeaks]

That's right! They are full of protein!

And proteins are a kind of nutrient that we need!

[Squeaks squeaks]

That's right Squeaks!—proteins can  help people to grow strong muscles.

And they're also why cooked eggs are hard!

If you had a really powerful  microscope, you could actually

zoom in and see all the proteins inside a raw egg!

They would kind of look like  folded laundry floating in water.

But when you boil the egg, the  heat makes the proteins unfold.

And the parts that unfold are really sticky —

so when the unfolded proteins bump  into each other, they get stuck!

After about 12 minutes, most  of the nicely folded proteins

end up stuck together into big, messy clumps.

And then if you zoomed back out, you'd see that

all those clumpy proteins make a solid egg.

Now, what do you think will happen to  our solid egg when it cools back down?

[Squeaks squeaks]

Ah you got it! Even though the heat is gone,

the proteins stay stuck  together, so the egg stays solid.

That means you can't "uncook"  an egg by putting it in ice.

Once it's solid, it stays that way.

Ooo, but what if I took the egg out earlier —

like, after just five or six minutes?

[Squeaks squeaks]

That's right! It takes time for the  proteins to unfold and stick together.

So, if you pull the egg out of the water earlier,

it's somewhere in between goopy and solid.

The longer we boil and heat  an egg, the more proteins

can clump together, and the firmer  the inside of the egg becomes.

Some people actually choose to  pull their eggs out earlier,

because they like the middles  of their eggs to be a bit runny!

They call them “soft-boiled eggs”.

[Squeaks squeaks]

Ooo they do sound yummy, don't  they? You want to try making some?

[Squeaks squeaks]

Let's do it!

Cooking things can make some  big changes to your foods,

so it's a great way to try  some at home experiments.

With a grown-up's help, you can try soft-boiling

and hard-boiling eggs, too, and  observe the different textures.

I wonder which you'll think is tastiest!

Good luck with your experiments!

And remember, if you'd like to  keep exploring with me, Squeaks,

Mister Brown, and all of our friends,  make sure to hit the subscribe button.

We'll see you next time, here at the Fort.

[♪ OUTRO]