For me, Autumn doesn’t start with the first chill in the air or the changing leaves or paper cut outs of pilgrims and turkeys covering grade school walls. It starts with pie – pumpkin pie. I can get behind apple pie as the all-American pie and will commit unspeakable acts for a well made cherry pie; but for seasonal deliciousness, you can’t beat pumpkin pie.
There are a few secrets to perfect pumpkin pie. Maple syrup and bourbon are the easy ones. Adding maple syrup and bourbon to anything is like adding a double dose of awesome. You should seriously question the baking qualifications of anyone who leaves out the maple syrup and bourbon (I’m looking at you Betty Crocker).
The other secret is pretty easy too – the crust.
The secret to good pumpkin pie – to good any pie, in fact – is the crust, flaky, golden, crisp, melt in your mouth crust. The ingredients – flour, salt, fat, and liquid – may be simple, but the science of pie crust is still pretty interesting. As we examine the science of the flaky pie crust, we are also going to answer the long-standing debate over the best fat for pie making. Let get baking.
I’m going to take us through this recipe a little differently than I usually do. Normally, I would go step by step, examining the science of each step and the importance of the ingredients. With pie making, the ingredients can vary a bit, highlighted by the three-way debate between butter, shortening, and lard. We have all seen many variations on the basic pie crust recipe. We are going to discuss these variations, how varying the ingredients affects the crust. This week’s recipe does very specific ingredients, simply because my version is best. We’ll explore why my way is the best as well. To do that, we’ll start by walking through the basic pie crust technique, which will be used no matter the tweaks in ingredients. With that basic framework in mind, we can then talk about the different ingredients and what science can tell us about what they will do to our crust.
Hopefully, we all know what flaky pie crust feels like, but what is its basic structure? Flaky pie crust is really separate, thin, overlapping pieces of dough. Imagine the crust as a pile of playing cards swirled around on a table top. While you may have a solid-looking surface of cards with no gaps, it is actually individual pieces (flakes) overlapping each other. The ideal flaky crust has the same structure. The fat forms a barrier between the flakes of dough preventing them from sticking together and allowing the overlapping pattern. The same principle is used to create puff pastry and flaky croissants. Pie crust is just less time intensive.
Here’s how we achieve delicious overlapping flakes of dough and fat. First, we start with a solid fat, either our butter, shortening, or lard. A liquid fat, like oil, will mix with the dough and create a uniform product rather than the disparate flakes we are looking for. We cut the solid fat into small pieces about ¼ – ½ inch cubed. This is easy to do with cold fats. Refrigerating butter or freezing shortening and lard will give you cuttable consistency. We add the fat cubes to the dry ingredients (flour and salt) and lightly toss to get everything evenly distributed. Now we flatten the fate. That’s right I said FLATTEN the fat, not “cut it in”. Whatever gremlin is responsible for insinuating pastry blenders in to pie cookery should found and held under a bright light.
We want disks, not crumbs. And, yes, “pea-sized” pieces are crumbs.
Crumbs aren’t going to do us any good in creating flakiness. Crumbliness, yes. Flakes, no. Let’s use the deck of cards example again. Imagine that those cards spread over the table are the ones you’ve been using for poker night for the last several years. They’ve lost their slippery, glossy coat. They’ve had beer spilled on them a few times…maybe some nacho cheese. Much like the dough flakes of our crust, the cards are going have the tendency to stick a bit. Now imagine that we added a bunch of slippery new cards into the mix. Suddenly, the old cards aren’t sticking together, because the new cards are preventing contact between the sticky, old cards. This only works because the new cards and the old ones are the same shape (ie, flat). It would be much harder to try to mix something round like marbles into the cards. When we try this with dough, not only do the fats get smaller, but the dough pieces do as well, crumbs instead of flakes.
So, put down the pastry blender or pair of butter knives or whatever fiendish device that gremlin recommended. The only tool we need is attached to our arm just below the wrist. With the chunks of fat distributed through the flour, we are now going to get our hands dirty and start smashing the fat flat. Simply pinch the fat pieces between thumb and finger so that they are flat disks roughly the size of a quarter.
That’s it. Done. Stop playing with it.
I mean it. If you keep playing with it you’re going to break it.
Remember, we want the fats to be solid. If they become liquid, they will mix into the dough and destroy our flakes. All of our fat types will soften and some will melt (especially butter) from body heat. So, it is important to work fast. This is also why starting with cold ingredients – cold fats and cold liquids – is important. Now that we have flattened disks of fat evenly dispersed through the flour, it is time to add the liquid.
You will notice that, like many pie crust recipes, our recipe has a range for the amount of liquid. This is because the amount of liquid your flour can take will depend on the day. The starches and proteins in flour want to bond with water. In fact, they are so desperate for water that they will actually pull moisture out of the air. On a wet or humid day, the flour has more access to water in the air and will pull more out of the air. Because the flour now has added moisture to it, we will have to add less liquid when we make our dough. Unfortunately, there is no great way to predict how much liquid your flour is going to take on any particular day. We are just going to have to add the liquid slowly and look for our dough to tell us.
We’ll start adding the liquid by drizzling about 1/3 of it over the flour/fat mixture. Then, with our hands, we will toss the mixture like a salad. Light hands. We don’t want to mix the fat into the flour anymore, just distribute the liquid throughout. Again, think dressing a salad. After that first third, we continue to slowly add more liquid until the dough is in ragged clumps. These will be big chunks that almost stick together when pressed, but don’t end up holding. At this point, we need to let the dough rest before doing anything else. This resting time will let the glutens relax making for easier rolling, allow the water to more evenly distribute itself through the dough, and let the butter chill down again. So we pat our dough into a disk, wrap it in plastic wrap, and place it in the fridge for one hour.
At the end of that hour, our dough is ready to roll and bake. With pie crust there are three different types of baking that we could do. Baking the raw crust and filling together, is one that I almost never use. The moisture of the filling never really allows the bottom crust to bake thoroughly and become flaky and crispy. Fully cooking the crust (known as blind baking)can give a better crust. I typically only use blind baking for an unbaked filling. While we don’t want soggy undercooked crust, we also don’t want the crust to overcook and burn on the edges. Partially cooking the crust (known as par-baking) is a good compromise, and our choice for our pumpkin pie.
To par-bake (or blind bake) our crust, we are going to roll out the dough, form it into the pie dish, trim off excess dough and then line the inside of the dough with parchment paper1. We then want to fill the crust completely with pie weights2. It is very important to fill the pie completely, not just the bottom. The weights not only hold down the bottom of the crust, but also hold up the sides. Remember, we’ve got a lot of fat in the crust that tends to melt. Fill the crust with pie weights or risk melting the sides of your crust. Now, put your crust into the oven at 350F. After 20 minutes, we can remove the weights and paper (for both blind and par-baking). Our crust is ready for the pumpkin filling. To continue blind baking our crust, all we have to do is place the crust back in the oven for another 10 minutes.
To finish off our pumpkin pie, mix all of the filling ingredients together. No secret chef trick here or crafty science – everything in a bowl and whisk. The mixture pours into the par-baked crust and back into the oven at 325F for about 45 minutes. We can tell when it is done by tapping the pan. Liquidy waves in the center equals not done. Jello-like shimmy in the middle equals done.
Now that we know how to make our pie no matter the fat or liquid we choose, let’s talk about which ones are the best.
As we’ve already discussed, the purpose of the fat is to separate the flakes of dough. It is doing this job both before it hits the oven and while it bakes aways. However, it is the time in the oven that really makes a difference in flakiness. This all comes down to melting temperature. Quite simply, we need a fat to stay solid long enough for the dough flakes to cook into crust flakes.
The higher the melting temperature, the longer the fats stay solid. The longer the fats stay solid, the longer the dough is held apart. The longer the dough is held apart, the more flakes in our crust.
If high melting temperature were our only criteria, shortening would be our fat of choice. Thanks to the engineering prowess of Proctor & Gamble, we have a solid fat that melts at a high temperature, making it ideal for creating a flaky crust and greasing squeaky hinges. There is, however, a dark side to such a high melting temperature fat: mouthfeel. One of the reasons butter crusts are so popular is mouthfeel. Whenever you hear someone mooning over how buttery a crust is, what they are really experiencing is a “melt in the mouth” quality. Because butter melts well below body temperature, it melts away when we eat it, giving a smooth, clean feel. Shortening, on the other hand, with its high melting temperature, will not melt in the mouth. This tends to leave us with a greasy feeling in the mouth and a drier texture to our crust. A lot of chefs and home cooks compromise by making their crusts with half butter and half shortening. A common, if not ideal solution. But there is another contender, the Rocky Balboa of the fat world: lard.
A few generations ago lard was the fat of choice for pie crusts. And guess what? Great-grandma was right. Despite the fact that lard is hardly ever used anymore, it will make a better crust every time. Lard’s melting point is midway between that of butter and shortening, and still below body temperature. This means that lard will last longer in our crust than butter (more flakiness) and melt in your mouth, giving the “buttery” feel. Magic? No. Just another example showing that pigs, not sliced bread, may be the greatest culinary invention ever.
I can hear some of you cringing at the thought of putting lard in your crust. No, it will not make your pie taste like bacon. Even if it did, bacon is tasty. But, no, lard is refined to remove any kind of pork flavor. Even more common is the comment, “But lard is so bad for you”. First, we are making a pie. This is not exactly health food. This is a delicious, delicious indulgence. Enjoy in moderation. Second, just how bad is bad compared to our other options? Is lard better or worse than butter?
If you guessed better than butter, you win. A tablespoon of butter contains 12 grams of fat. Of those 12 grams, 50% (6g) is saturated fat and only 30% (3.6g) is monounsaturated fat. Compare that to lard’s 13 grams of fat, composed of 39% (5g) saturated and 45% (5.9g) monounsaturated fat. With lower levels of the saturated fats we’ve all been told to avoid, lard turns out to not be as bad as butter for you. Again, not a healthy option, just not as bad. So, why does lard get the bum rap? The advertising campaign from Procter & Gamble, makers of Crisco, when they first developed their vegetable shortening, may have helped put a black mark on lard for generations to come.
With lard our winner in the fat debate, let’s move on to the liquid and answer the question, “Why wouldn’t you just use water?”
Recipes for pie crust almost universally choose ice water for the liquid component. More savvy recipes call for water with a little added vinegar. The problem with the ice water option is that it doesn’t account for the dual role of the liquid in the recipe. These recipes assume that the liquid is only there to bind the dough. But the liquid can also help separate the flakes. As the dough heats, liquid evaporates, creating steam. The increasing volume of steam pushes against the fat separated flakes and holds them apart on a cushion of air. Water is not a very good liquid for this job. By the time water reaches its boiling point, the flakes are mostly set.
This where the vinegar comes in. As one of our savvy patrons has pointed out, vinegar actually has a higher boiling point than water, raising the water from a 212 degree boiling point to a 213 degree boiling point (dramatic, I know). This pretty much debunks the kitchen myth of the vinegar solution creating more “puff” between the flakes. The belief behind the vinegar creating more flakiness likely arises from the fact that vinegar acts as shortener for glutens, reducing how tight and tough they bind. Great in theory, but I’m a little skeptical on how much good the vinegar really does. Let’s remember, that we have quite a bit of fat going into this crust, which happens to be the best gluten shortener on the block. The vinegar is like the outfielders at a pee-wee tee-ball game. Great back up, I guess, but really unnecessary. Besides, we don’t want our pie tasting like vinegar, right? (Thank for the contribution Trent).
The solution? Vodka.
Yes, vodka. Not to drink away our sorrows, for our pie. Mostly for the pie. Alcohol has a low evaporation point. In fact, at room temperature, alcohol will be merrily evaporating away. With its high alcohol content, vodka provides an early and consistent vapor source throughout the pie baking, pushing apart our dough flakes. Because vodka is essentially flavorless, it will also not contribute negative flavors to the pie. And, as a kicker, vodka will stay liquid in the freezer. This means that we can use ice-cold vodka to help the fats stay cold and solid. Perhaps not grandma’s recipe, but it gets the job done.
THE SECRETS: A POETIC RECAP
For those of you keeping score, the secrets to pumpkin pie number four: maple syrup, bourbon, lard, and vodka.
Happy eating, and drinking, if you have any “secrets” leftover.
1. Large coffee filters work particularly well for this too.
2. Dried beans also work, but are not ideal. After a few bakes, they start to give off beany smells into the crust. If you like making pies, invest in some ceramic pie weights.