The scientist's view of the kitchen world
After my quite serious and long post on scientific vs. religious mindsets, how about a nice, fluffy post on flour?
If you are anything like I was a few months ago, there was white flour and whole-wheat flour. End of story. Well, let me tell you that there is a much deeper story and it all revolves around chemistry.
You see, wheat is full of proteins. When these proteins get wet, they bind together into clumps. This is called gluten. Since no one likes eating dense, clumpy things, we like to stretch out our gluten through a process called kneading. Kneading also (to a lesser degree) helps introduce small air bubbles which expand when heat is applied, (think back to our ideal gas law, PV=mRT, as temperature increases, so does volume).
Fun fact: I discovered that rather than knead, one can pull the dough to achieve the same results! Pretty neat!
We run into a problem though, what about foods that aren’t very good when dense? Sure, a hearty bread is delicious (it needs to stand up under the weight of a hearty sandwich after all) but what about cakes, cookies, PIES? Here we introduce bread flour, all-purpose flour and pastry flour.
Basically, bread flour is full of protein (and gluten once it is wetted), all-purpose flour has less protein, and pastry flour has less still. This means that these three flours will make decreasingly less dense goods. And, what’s super handy, is their names pretty much tell you exactly what they are used for so there is no confusion at the store.
So yesterday I decided to make some apple pies. What’s more American than that? And since I didn’t have a pie pan, I used my large muffin tin instead for individual pies.
Pie crust doesn’t hold much flavor on its own and, frankly, I don’t think it should. The flavor comes from the filling, the job of the crust is to add that tender but flakey texture. And for that, we need to talk a bit about thermodynamics.
Pie crust recipes are easy:
That’s it. The trick to pie crust making is in the temperatures. You see, what we want to achieve is a suspension of large chunks of fat in a delicate mesh of gluten. We achieve that delicate mesh by using a low gluten flour – pastry or cake flour.
1. If you really want a perfect crust, measure out your flour and sift the flour and salt into a bowl. Then put about a cup of ice water, the flour, and the shortening in the back of the refrigerator and let it rest there for an hour. If you don’t chill your flour, you must at least chill your shortening. We need our shortening to be well solid so that it remains in its big-chunk state as we mix our ingredients.
2. When you are ready to mix, cut in the shortening to the flour mixture with only the tips of your fingers (which carry the least amount of heat). You can add the water when your shortening resembles about 0.5″ diameter chunks. If the shortening begins to get too soft, stick everything back in the fridge. Do NOT make a homogenous mixture – we still need those chunks of fat in there.
3. Then let it rest for 4 hours minimum. This rest allows the gluten to develop into that tender mesh. The low protein content of the cake flour ensures that our crust will turn out nice and light.
Time for some filling, eh?
My apple pie filling is pretty simple:
Honestly, these are all guesses on my measurements. I just mix everything together until it tastes right. Right, in the uncooked stage, should taste a touch too cinnamony. The cooking process will melt the sugar and release juices in the apples so if they are perfectly sweet prior to cooking, they will be too sweet once they are done. Also, the citrus can be mixed to taste. I like it because it adds a subtle brightness to the food.
Cook at 350 degrees F for 30 minutes covered with aluminum. The cooking process melts the fat in the dough. The empty cavities left behind by the fat chunks give you that extra flakey texture when the pies are done. Also, always cook with the dull side of the aluminum facing the pie. It doesn’t make too much difference but the shiny side reflects more heat than the dull (we’ll get to radiative heat transfer in another post). Good rule of thumb: shiny side means crispy, dull side means soft. After 30 minutes, remove the foil until the crust is brown on top.
Now, I did an adorable lattice top for my pies (cut rolled out pie dough into strips using a pizza cutter and weave over the tops of your pies) and I would love to show you but somebody decided to jump up on the counter last night and eat the tops right off of my last two pies:
So you will just have to trust me that they were delicious. Here is the aftermath:
I guess I’ll just have to bake them again!