May 13, 2016

MacKenzie Masten

Take a Bite Out of Science: National Apple Pie Day!

Topics: Learning Through Play


Apple Pie - Sliced Apples

I love cooking, ask anyone who knows me and they’ll tell you that food is a passion of mine. Now I don’t love cooking solely because I love food and the way it tastes. I love cooking because I really learned to appreciate food and how it works after learning the science behind cooking. Cooking is essentially an edible version of chemistry. There are chemical reactions that take place in your food as you heat them or add certain seasonings that change the complexion of the dish. You can take flour and transform it into a fluffy sweet cake thanks to the chemical reactions that happen when you add certain ingredients together. Cooking and baking are just tasty science experiments!

So why are we writing about food? To make you hungry? No! The reason we are writing about cooking is because for the next week we will be doing posts about how you can teach your kid some basics about science through cooking. And the best part about this is that once you’re done learning about how cookies are made, or why a cake rises, you get to eat scrumptious treats!

To celebrate it being Friday and National Apple Pie Day, we’ve got a great recipe and an explanation of the science behind what makes apple pies so tasty. (Photos courtesy of Katie Vincento @ktvincey).


For this experiment you will need the following

  • 4 to 4 ½ pounds of Golden Delicious, Braeburn, or a baking apple of your choice; peeled, cored, and sliced into ¼-inch slices
  • 3 quarts boiling water
  • 10 tablespoons granulated sugar, plus 1 tablespoon for sprinkling over the crust
  • ¼ teaspoon of cinnamon
  • ¼ teaspoon salt
  • 2 to 4 tablespoons cornstarch
  • 2 ½ cups all-purpose flour
  • 2 tablespoons of sugar
  • 1 teaspoon of salt
  • 2 ½ sticks unsalted butter, cut into ¼-inch sections
  • 6 tablespoons cold water
  • 1 egg white, lightly beaten


  • Preheat the oven to 425°F.
  • Place the apple slices into a large bowl and pour boiling water directly over top. Cover the apples and set aside at room temperature for ten minutes.
  • Drain the apples and wait until they are completely dry, about 10 minutes.
  • Transfer the apples to a large bowl and add sugar, cinnamon, salt and cornstarch. Toss until apples are evenly coated and then set the mixture aside until the pie crust is ready.

Apple Pie Crust Ingredients

  • For the pie crust, combine 2/3 cup of flour with sugar and salt in the bowl of a food processor. Pulse twice to incorporate. Spread butter chunks evenly over surface. Pulse until no dry flour remains and dough just begins to collect in clumps, about 25 short pulses.

Make Apple Pie Dough

  • Use a rubber spatula to spread the dough evenly around the bowl of the food processor. Sprinkle with remaining flour and pulse until dough is just barely broken up, about 5 short pulses. Transfer dough to a large bowl.
  • Sprinkle the crust with water and then, using a rubber spatula, fold and press the dough until it comes together into a ball. Divide the ball in half. Form each half into a 4-inch disk. Wrap the disks tightly in plastic wrap and refrigerate for at least 2 hours.
  • Roll one disk of pie dough into a circle roughly 12 inches in diameter. Transfer the crust to a 9-inch pie plate and add the filling. Make sure to discard any excess juices in the bottom of the bowl - they will make your crust soggy.
Peeled and Sliced Apples
  • Roll the remaining disk of pie dough into a circle roughly 12 inches in diameter. Transfer it to the top of the pie and trim the edges of both pie crusts until there’s about a ½ inch crust overhang around the edges, then tuck the edges around the pie pan. Cut 5 slits in the top of the pie with a sharp knife for proper ventilation.
Apple Pie Dough and Filling
  • Use a pastry brush (or a fork) to brush an even coat of lightly beaten egg white over the entire top of the pie. Sprinkle the tablespoon of sugar evenly across the top of the pie. Place the pie in the middle rack of the oven and bake for about 20 minutes, or until golden brown. Then reduce the heat to 375°F and continue baking for about 25 minutes longer, or until a deep golden brown. Remove from the oven and allow to cool for 2 hours before serving, (We know it’s hard, we’re sorry).

Apple Pie Slice

 The Science Behind Pie:

Have you ever wondered what makes a pie crust so flakey and crisp? Do you think it is a result of baking it at a high temperature for a long period of time? Or maybe it’s something that you just thought happened because it’s supposed to. Well, pie crust develops flaky layers due to the combination of flour, butter and cold water.  The key to a successful pie crust is the balanced interaction of gluten and fat. When you combine the butter and flour mixture, you create pockets of buttery goodness, otherwise known as fat.

When you combine the flour and butter mixture with water, you are creating gluten, which allows you to stretch and form the pie crust as you like. Gluten is the network of proteins that lend structure to baked goods. It makes the crust malleable, but the butter and the fat that comes from the butter is the true star in creating a perfectly flaky pie crust. When you roll out the pie dough, you stretch out the fat pockets that separate the sheets of gluten filled dough. Then, as you bake the pie crust, the fatty layers melt and allow the floury layers to separate from each other, solidify, and form the layers you see in a flakey pie crust.

Applie Pie Filling Ingredients

There’s more science to a pie than just in the crust. Pouring boiling water over apples seems a bit odd right? The reason we pour boiling water over the apples is to make sure the apples retain their shape when baking. When you place raw apples into a pie and bake it, you run the risk of creating a pie that has a mush like filling. This is because when you cook apples, they cell walls within the apple slices expand and release the heated air within them, creating a translucent and soft apple filling.

This all sounds great right? Unfortunately, while your pie filling is ready to eat after about 25 minutes in the over, your pie crust is still pale and uncooked. So you have to bake the pie longer in order to create an edible crust, but that makes the apples lose any form of structure that was once holding them together. Boiling the apples essentially cures them—similar to how the mortar in between bricks needs to cure in order to fully harden. By cooking the apples in boiling water, you are able to heat the apples and prepare them for the pie without ruining the filling or pie crust. Apple_Slice__bite.jpg


Want to learn more about food and science? Keep an eye out for our next post on Sunday May 15, in honor of National Chocolate Chip Cookie Day! Photos courtesy of Katie Vincento @ktvincey.

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