The secret behind a flaky pie crust!

It's no secret, it's science!  Take a tip from our guest blogger Helen, a former chemist -

The following are some lessons learned with my recent pumpkin pie. The most amazing part is the crust did not turn soft till the third day - when I polished off the last piece and the bottom was just starting to soften.

Here's the secret. After rolling out the dough and transferring it to the pie pan, refrigerate for 40 minutes, then freeze for 20 minutes. Bake with pie weight (I use pennies) till almost done, then add hot pumpkin filling while the crust is still hot from the oven and finish baking. (I had some angst as the pie plate is pyrex and I had to move it from freezer to hot oven)

The LONG scientific explanation is "Gluten is formed when water is added to flour. During rolling the strands of gluten get stretched and if not allowed to rest they will snap back when baked. Resting does not occur if the crust is placed immediately in the freezer after rolling as the water freezes and holds the gluten in place... Frozen crust is much flakier than refrigerated crust... Dough and fat have different heat tolerances. For frozen dough the dough heats up and starts to set relatively quickly compared to the time the frozen butter takes to melt and then vaporize. By the time the water in the butter turns to steam, the dough has started to set and hold the shape, rather than allowing the soft dough pockets to collapse and hence make the dough denser..." If you have the book Baking Illustrated from the Cook's Illustrated, a more detailed explanation is on the section on “Pies and Tarts”.

A few other tips gleaned from the book:

1.      Crisco shortening makes flakier crust, as “the oil has been hydrogenated, when hydrogen gas is pumped in to incorporate air and to raise the melting point… Crisco is 10% gas and does a good job of lightening and tenderizing”. However if hydrogenated oil is worse or as bad (healthwise) than butter, I’d prefer to use butter. But that means revamping my 15 year old tried and true pie dough recipe.

2.      “Some liquid ingredients tried included buttermilk, milk, cider vinegar, etc. and none were deemed better than water”. I have however experimented with vodka as the liquid, with the rationale being that it evaporates during baking and hence I can make the dough softer and easier to roll out.  I’ll try this the next time, as “less water means a more tender dough”.

3.      When rolling out dough, “make sure it is well chilled before rolling, and add a minimum of flour to the work surface…If the dough seems too soft to roll, it’s best to refrigerate rather than add more flour”

4.      For pumpkin or custard-like pies, “pre-bake pie crusts…make sure that both shell and filling were hot when assembling the pie, so the custard could begin to firm up almost immediately rather than soaking into the pastry…Bake on bottom shelf, where the bottom of the crust is exposed to the most intense  heat”

Enjoy your baking adventure!