Gluten develops in dough when two wheat proteins found in flour (glutenin and gliadin) are mixed with water. Because parts of these proteins don’t like to interact with water, the proteins begin to stick to each other much in the same way oil droplets come together when suspended in water. As a flour-water dough is mixed, the glutenin and gliadin molecules interact to form a protein network.
These networks give structure and stability to dough. Although dense networks are great for chewy bread dough, they are less than ideal for flaky, tender pie crust. An ideal pie dough has as just enough gluten to hold everything in the dough together. And while gluten development can be minimized by adding only scant amounts of water and handling the dough as little as possible, this is easier said than done.
What flour is the best flour for pie crust? This is a contentious question that has a variety of answers depending on personal preference, but the type of flour you use can have a major effect on the final texture of your crust. The protein content of flour, based on the type of wheat the flour was made from, will affect the extent of gluten formation in your dough. Bread flour has particularly high protein content, which can make pie crust dense and tough. Flours with lower protein content, such as pastry flour or cake flour, will create less extensive gluten networks and can produce a more tender crust.