Why Does Bread Have Holes In It? | The Science of Cooking | SciShow Kids

Oh, hey Squeaks! I was just thinking about what we would have for lunch. And I know it's not for a while, but it's never a bad thing to think ahead. What sounds good to you? Sandwiches do sound good. Maybe a PB&J and what about you? One cheese sandwich coming right up. We might have a bit of a problem. We're out of bread. I have an idea. We could make our own bread. It would be fun. And baking bread is a great way to learn some science. Oh, yeah, there's a lot of science that goes into making bread. Like, did you know that our sandwich bread is soft and yummy thanks to a microscopic living thing? It's called yeast, and it's part of a special group of living things we call fungi. That's right. We've seen fungi before, like the mushrooms and toadstools we see on our hikes, or the mold that grows on food if it sits for too long. Yeast are much smaller than those fungi. A single yeast is so small that we would need a microscope to see it. But even though they're small, they're also mighty, because they are what turns these ingredients into yummy bread. Let's get started. To make our bread, we're going to need flour, salt, warm water, sugar, and some yeast. We'll start by adding just a bit of sugar to this warm water. Then we'll want to add our yeast, this brownish stuff. You're right, Squeaks. You can see these because each little tiny piece here is actually hundreds of thousands of little yeasts clumped together. Right now, they aren't very active. It's kind of like they're asleep. But when they get mixed with the warm water, they wake up. And they wake up hungry, so they start munching on the sugar we added to the water. But it's what comes after they eat that's important. You know how, after you eat, you sometimes have to burp or fart? That's because your body makes gases. Yes, you're right. Air is a mixture of gases. And when we pass gas or burp, our bodies are getting rid of extra gases that are trapped inside us. Well, these yeasts make gases when they eat, too. So you could say they fart a lot. Which is why our sweet yeast water now has bubbles in it. So now that our yeast is awake and eating, we can mix it with the flour and salt to make our bread dough. The yeast will keep eating the sugar we added as well as some of the flour. And they'll keep making gas, most of which will get stuck inside the dough, forming bubbles. And those bubbles are the little pockets of air that make our bread light and fluffy. Here's some dough I mixed up earlier. That's true, because it's not bread yet. It's bread dough. We've got to cook it to actually get bread. Now, sometimes in the kitchen, if you heat something up, you can cool it down again so it goes back to the way it was at the beginning. But that's not true of bread. Right now, it's sticky and squishy. But when it gets hot, it becomes stiffer and the outside even gets a crust on it. So it's important to make sure your dough is all ready to go before baking. In fact, those yeast are still eating and farting right now. And the more time we give them to do that, the more bubbles they'll make and the fluffier our bread will be. So we've got to let our dough sit for an hour or two before we can bake it. Let's go for a walk in the meantime. And then once it's in the oven, we can start getting everything together for our sandwiches. Oh, look! The dough is much bigger than when we left it. And it's puffier, too! This is what bakers call rising, for obvious reasons. It's full of bubbles, all thanks to those hungry yeasts. If we mix the flour, salt, and water together, we'd still get dough. But it wouldn't get nice and fluffy. It would just stay flat. It takes the yeast to get the bread to rise. It's time to put this in the oven to bake. Our bread is all done baking. It smells so good and it looks so different. Our bread dough was pale and kind of white and very soft and sticky. The baked loaf is brown and crusty on the outside. Let's cut into it so we can look inside. Check out all the little holes! Those are what's left behind from the bubbles made by the yeast. They make the inside of the bread nice and soft, but it's not squishy like it was before we baked it. And we can't separate it back into flour, water, sugar, salt, and yeast. We just get a mess of crumbs. But I would rather have a sandwich. How about you, Squeaks? Yes, let's have lunch! Hey, thanks for joining me here at the Fort! If you want to keep learning and having fun with Squeaks, me, and all our other friends, be sure to hit the subscribe button. And we'll see you next time on SciShow Kids! Bye!