Pie crust, also known as pastry, is a type of dough made from flour, fat, and water that is used as a base for many types of pies. One common issue that bakers may encounter when making pie crust is shrinkage, or the crust becoming smaller in size after baking.

There are several reasons why pie crust may shrink during baking. One of the main reasons is due to the presence of gluten in the flour. Gluten is a protein that gives dough its elasticity and structure. When the dough is rolled out and placed in the pie dish, the gluten begins to relax and stretch. However, when the pie is baked, the heat causes the gluten to contract, leading to shrinkage of the pie crust.

Another reason for pie crust shrinkage is overworking the dough. When the dough is handled too much or rolled out too thin, it can become overworked and lose its elasticity. This can also cause the crust to shrink during baking.

The type of fat used in the pie crust can also contribute to shrinkage. Butter, which is a common fat used in pie crust, has a lower melting point than some other fats, such as shortening or lard. This can cause the butter to melt too quickly in the oven, leading to shrinkage of the crust.

Another factor that may contribute to pie crust shrinkage is the type of pie dish being used. Glass or ceramic pie dishes tend to conduct heat more efficiently than metal dishes, which can cause the crust to shrink more.

In conclusion, there are several reasons why pie crust may shrink during baking. These include the presence of gluten in the flour, overworking the dough, the type of fat used, and the type of pie dish being used. To prevent shrinkage, it is important to handle the dough gently and use a pie dish that conducts heat less efficiently.