Why Does Cooking Eggs Make Them Hard? | The Science of Cooking | SciShow Kids

Hi there! It's snack time here at the fort, so Squeaks and I are having a quick break from our busy day to eat. Oh, I brought something new for a snack today, Squeaks. I brought some hard-boiled eggs. I can crunch up the shell a bit and then peel it off with my hands. And then a little sprinkle of salt for flavor. And yum! Oh, that's true, Squeaks. Hard-boiled eggs are quite a bit different from raw ones. They may 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? 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. Oh, 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? Yeah, it is a tough question, but how about this? What do we know about eggs? They are really yummy, and they're also really good for us. Do you remember why? That's right! They are full of protein, and proteins are a kind of nutrient that we need. That's right, Squeaks! Proteins can help people 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? 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. Ooh, but what if I took the egg out earlier, like just after 5 or 6 minutes? Oh, 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 middle of their eggs to be a bit runny. They call them soft-boiled eggs. Ooh, they do sound yummy, don't they? Do you want to try making some? 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, Mr. Brown, and all of our friends, make sure to hit the subscribe button, and we'll see you next time here at the Fort!