Why not just use all butter? So asks reader Victoria. Victoria, the main reason North American pie makers use shortening (or lard) in their crusts, instead of just using all butter, is to keep the moisture content as low as possible. Butter can be up to 18% water, and that can be a very bad thing for the texture of a crust.
We talk about gluten a lot on the site. That’s because North American gluten can be a real pain to work with, making pastry tough and prone to shrinkage in the oven. Gluten is always present in wheat flour, but it takes water to “activate” it, which is to say, cause the gluten molecules to bond to one another in a springy network. So we a.) minimize the amount of water that’s in the crust, and b.) try to work it as little as possible since agitation is the other thing that activates gluten.
If we were all living in France we could probably employ some of their “dry butter” for our crusts, that might solve the problem. However we aren’t in France, and making dry butter is a hassle, so we make do with whatever’s available. Normally that’s vegetable shortening, but as I said above, some bakers use lard, which is also very low moisture. Some bakers use 100% lard in their crusts, which makes for superior texture but tastes a little “piggy” for some people. Vegetable shortening offers a neutral flavor and brings no water whatsoever to the party.
My favorite crust is 50% butter and 50% lard. But the trick there is that great baking lard can’t be bought these days, it has to be made. Which I suppose is another reason most people, faced with a choice between rendering their own lard and simply buying shortening, choose the shortening. Thanks Victoria!