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Due to an offhand comment, I managed to get myself embroiled in a local pie baking contest. They say that careless talk costs lives, but it apparently bakes pie as well. Given that I need to concentrate on the subject at hand, I figured I would ask if anyone had any pie related questions. Although a couple of people mentioned Shoefly pie, as apparently today is Shoefly Pie Day in Pennsylvania, but most people wanted to talk about pie crust.
Because of the pie crust demand, we talk pie crust. We may even chat a bit about vodka, as that ranked at least as high as Shoefly Pie.
Because all of the questions dealt with flakiness and/or vodka, we know that the specific type of pie crust being asked about is the pastry crust. Pies can have other types of crust, especially the crumble-style crust, which is usually a cookie or similar that's been turned to crumbs to application of force and bound together with some fat. That kind of crust is not flaky, and as you'll soon see, there's no need for vodka with that kind of crust.
Therefore: pastry crust. Pastry crust is made by the biscuit method: take some flour, mix it in with fat, add some liquid, let sit, form and bake. Simple, right?
Any time we mix water and flour, especially if we mix it, we get gluten. If you're not familiar with gluten, go back and read about Which Flour Is Best with Pasta, and you'll know the basics. In short, flour contains two proteins, glutenin and gliadin. When combined with water, glutenin and gliadin join together and form gluten. Gluten is the muscle of dough, so more gluten makes a tougher dough.
Pie dough is graded on a continuum of tender to flakey. At one end, you have a crust that will offer no resistance to fork or teeth, and will simply melt upon the tongue and add a counterpoint of flavor to the pie in question. At the other end, you have a flaky crust that can not only last for days with a moist pie filling sitting on it, but that could hold the weight of the filling if you pick it up by one end.
What type of dough you need depends on the pie your making and your personal preferences. Generally, the serious pie aficionados lean towards something in the middle, that is both tender and flaky. Why? Oh, people will say it offers the right balance of blah and blah, but we all know the real reason: because it's hard, and it gives them bragging abilities when they do it well.
Fear not! Just because it seems difficult doesn't mean that a little knowledge and a decent amount of practice won't get you a long way. The knowledge can come from a number of sources, my two favorite on this subject being Bakewise, by Shirley Corriher (naturally), and The Pie and Pastry Bible by Rose Levy Beranbaum, but you may have your own sources. There is much pie knowledge in the world.
To make a pie tender, you need to reduce the amount of gluten being formed. To do that, you reduce the amount of water that contacts the proteins in the flour. There are four standard ways to do this:
- Use a low-protein flour. Flours from southern climates are generally "softer", meaning there's less protein. Flours from northern climates are generally "harder", with more protein. Cake flour has the least amount of protein, but has a distinctive flavor. All Purpose (AP) flour has a middle amount of protein, and bread flour has the most. In general. A pastry flour is in-between AP and cake, and you can approximate it by mixing AP with cake flour. Rose Levy Beranbaum likes to use the pastry flour.
- Coat the flour with fat. Fat doesn't mix well with water, so water is repelled from the flour, and thus reduces gluten formation. Using butter, which has a low melting point, will help this along, because the butter melts while you're working it. There are various tricks along these lines to increase or decrease gluten formation, but they're all about either keeping the dough chilled or allowing a good coating of potentially liquid oil, respectively.
- Reduce the water content in the liquid. This is the technique that Cooks Illustrated has used with Pie Crust, as mentioned above, and I've also seen it used in fish batter. If you use a liquid that will bring the dough together without increasing gluten formation, then you can have a crust that is more tender. Alcohol is a great liquid for this, when used in moderation. Vodka is a relatively neutrally-flavored and -colored spirit, so it's popular. You could also use a more flavored spirit if it goes with the flavor in your pie. Experimentation is a good thing here.
- Minimal physical agitation. The less moving the dough does, the fewer opportunities the glutenin and gliadin have to meet up. If they can't meet up, they can't join. This means that if you make a mistake in the rolling and have to fold it back up and start over, you're going to have a tougher crust. That doesn't mean it will be a bad crust, it just might not be as tender as you were hoping.
In the case of flakiness, there's something a bit different going on. Flakiness happens when you have whole chunks of fat, flatten into sheets, between your floury parts of the crust. If the fat doesn't melt before you bake, then you have the opportunity for flakiness. See, the floury parts of the dough will start to bake while the fat starts to melt. This causes the floury bits to form their own islands, while the fat keeps it separated from the other islands. Thus, when you bite or cut into the dough after it cooks, it breaks off in flakes, which are those baked islands of crust.
To promote the flakiness, you need to prevent the fat from melting while you're working it. If you have a fat that has a relatively high melting point, then you have an easier job of it. Shortening has a high melting point compared to butter, but butter tastes better than shortening. Some people like butter-flavored shortening as a compromise, which is certainly an option.
Of course, if your pie can handle it, lard is the way to go. The perfect combination of high melting point and flavor. Health concerns? Piffle. Lard is currently* far healthier than shortening, and people are not as afraid of the lard bogeyman as once they were.
You can also use a combination of butter and shortening. How you cut the fat and how you combine it also contribute to the equation, and it doesn't make sense to overwhelm you with those now. However, you should now have everything you need to be able to look at a pie crust recipe and determine if it's going to be flaky, tender, or some combination. Get some practice in, and you'll have a tender and flaky crust in no time to shame everyone who buys a pie crust from the store.
*- That's right, currently. Are eggs good for you? Is butter healthier than margarine? Scientific opinion changes as time goes on, but flavor is forever. Don't overdo it, and you'll be fine.