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  • [♪ INTRO]

  • 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 bitthen 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 quitebit 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 eggthere's a clear, goopy, liquid part,

  • called the egg white, andsmaller 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 "uncookan 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 themsoft-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 friendsmake sure to hit the subscribe button.

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

  • [♪ OUTRO]

[♪ INTRO]

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B1 中級 美國腔

为什么煮鸡蛋会使它们变硬?(Why Does Cooking Eggs Make Them Hard?)

  • 16 2
    joey joey 發佈於 2021 年 05 月 07 日
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