Basic pie dough: fat, flour, water
I don’t have much to add to the science of basic pie dough. I stand in the footsteps of giants—notably J. Kenji Lopez-Alt, who developed a newfangled way to reliably make great, flaky pie dough. His recipe eschews the traditional “cut cold butter into a mass of flour until pea-sized clumps form” method. Instead, you food-process the butter (and optional shortening) with some of the flour to make a fat-flour paste. Then you throw in the rest of the loose flour, add water, and squish to combine. Solid clumps of the fat-flour paste melt and spread out to form flaky layers. And the loose flour bonds with water to form just the right amount of gluten, the stretchy protein that gives baked goods structure (more about elasticity).
I love this recipe and I’ve used it many times. But I wasn’t sure how to incorporate pecans.
I didn’t want to just throw in loose ground pecans, because I figured they’d wreak havoc on the dough’s delicate texture. So for my first test, I substituted ground pecans for some of the flour in the fat-and-flour paste.
Failure! The crust wasn’t nearly flaky enough. At its worst, the crust had the texture of a soggy pecan sandy. (On the plus side, I did determine that the pecans should be toasted.)
In the first pie, I used all butter, which melts easily. When the fat’s too soft, you get a homogeneous, crumbly texture instead of flaky layers.
So for my next pie, I tried the same method with a lot more shortening, which stays solid for longer than butter.
Still no good. If anything this one was even more soggy and crumbly.
Maybe I was just overprocessing the dough, but I didn’t feel like making yet another pie with the same method just to make sure.
I decided to take a step back. What are pecans, anyway? As it turns out, pecans are almost 70% fat by weight. I had been treating the pecans as a substitute for flour. Maybe I should treat them as a substitute for fat?
In my next pie, I tried two very different approaches. For the top crust of the pie, I did what the facts about pecans seemed to suggest—I treated them as a substitute for fat and used less butter. I very finely ground the pecans with one tablespoon of shortening until a smooth paste formed, and I threw it in the freezer before proceeding, to ensure the pecans were as fat-like as possible.
For the bottom crust, I took the exact opposite tactic: I treated the pecans as a substitute for flour. And this time, I added them at the end, with the loose flour. So unlike all my other pies, the bottom crust’s pecans were not part of the fat-flour paste.
I did not expect the bottom crust to work. In fact, I assumed the bottom’s failure, and the top’s triumph, would prove my hypothesis: that pecans are basically fat and so should be treated like fat in a pie dough recipe.
I was wrong! Look at those flakes on the crust rim. That’s part of the bottom crust, the supposed failure, but it came out perfect. Excellent flakiness, tender texture, and intense pecan flavor. The top crust had a somewhat flakier texture than my previous experiments, but it wasn’t as flaky as the bottom, and it tasted a lot worse—almost rancid.
Pie (single crust)
|Pecans||Fat / Flour ratio||Result|
|Original recipe||None||10 tbsp / 1 ¼ cups||Flaky|
|Pie #1||Untoasted, processed with fat-flour paste||10 tbsp / 1 cup||Crumbly, needed toasting|
|Pie #2||Processed with fat-flour paste||10 tbsp (extra shortening) / 1 cup||Crumbly|
|Pie #3, top crust||Ground with 1 tbsp shortening to paste, chilled, processed with fat-flour paste||8 tbsp / 1 ¼ cups||Slightly less crumbly, weird taste|
|Pie #3, bottom crust||Pulsed in with loose flour||10 tbsp / 1 cup||Flaky|
A tale of two fats
Why had my experiment shown the exact opposite result I was expecting? I believe it has to do with the difference between saturated and unsaturated fat.
Butter is largely saturated fat, which means it stays solid at room temperature. (Shortening is made from unsaturated vegetable oil, but it’s hydrogenated—basically an artificial saturation process, which makes it solid at room temp like butter). When those bits of cold, solid fat in pie dough melt in a hot oven, they spread out between sheets of gluten—that’s where flakiness comes from.
Pecans, on the other hand, are mostly unsaturated fat, which means the fat is liquid at room temperature. It can’t melt and spread out, because it’s already liquid. So even though pecans are indeed fatty, that fat just doesn’t behave much like butterfat or shortening, nor does it play well with those solid fats in the dough’s fat-flour paste. Hence, better to treat the pecans like loose flour, rather than trying to incorporate them into the fat-flour paste.
Why don’t those loose pecans mess up the dough’s texture? Because unlike flour, pecans don’t form gluten with water. Thus, they don’t affect the dough’s balance of gluten and fat—they just sort of sit there, in the background of the equation.
So there you have it. I may not have cured cancer or found the Higgs boson—I didn’t even manage to win the pie contest, alas—but I hope I’ve at least done my part to advance the science of adding nuts to pie dough without sacrificing flakiness. (recipe here!)