After a long month's baking, we're tackling one of my favorite pies today: Lemon Meringue.
I learned how to bake this pie from my mother, who baked it frequently for my father--an ardent fan of lemon meringue. So much so in fact, that he jokes about ranking prospective brides based on their ability to execute the pie well.
Unfortunately, my mother made something we Humbles call "Lemon Meringue Pool". Tasty but structurally… well, a disaster (sorry mom). When served, the filling would be slack and form a puddle on the plate. Hence the name. I'd post photos of lemon meringue pool, but to save mom face I'll post a quick doodle of a sad pie that appears to have wet himself.
|You get the idea.|
My dad married her anyway, so I'm assuming Mother Humble's other qualities were such that my father was willing to overlook this quite grievous flaw.
Having learned how to make this pie at her side as a child, I inherited the recipe and its problems. As an adult I've had to endure the shame of delivering pies to my father with decidedly slumpy qualities.
Luckily those days are over and I can produce pies with that perfect firm, silky filling that cuts beautifully yet melts in the mouth.
|Pie made with the exact same standard ingredients as Mr. Pee Pants Pie above|
I know I'm not alone in my troubles with lemon meringue pie. I've seen plenty of soupy pies and botched meringues posted by their irritated and baffled bakers on my quest for the perfect pie recipe.
It was only after dozens of recipes that I realized that I was approaching it all wrong. It wasn't necessarily the recipe that was dooming my pie filling to get a little slumpy, it was chemistry.
You see, the elements that make up the filling for this pie don't really get along.
They hate each other.
They hate each other like those dysfunctional families on day-time talk shows, screeching and throwing chairs at each other.
|Starch Granule, Lemon and Heat|
So tasty... yet so troubled
Let's talk about why they're so unhappy together.
We rely on starch to thicken the lemon filling. After all, without it we'd be filling the pie with what is essentially lemon curd.
Typically, you will see corn starch or wheat flour being called for as a thickener. (I prefer the former, since corn starch beats flour hands down in thickening ability, flavor, and texture.) Unfortunately, the lemon juice, the heat you're cooking over, the fat and even enzymes in raw eggs can all work against the thickening ability of starch.
Let's start with the issue of acid.
Mother Humble's problem was her love of extra tart lemon meringue pies (which I admit to sharing). She would make hers with a generous amount of lemon juice. Unfortunately, out comes the dysfunctional pie family dynamic and the lemon juice gets in a hair pulling match with the starch. The acid in the lemon limits the ability of starch to capture moisture, contributing to the sad pooling in the bottom of Mother Humble's pie tin.
So when crafting and testing a lemon meringue pie recipe, we need to be sure we use enough juice to provide that bright lemon flavor, but not so much that our starch can't do its job. Using a bit less sugar is a better means of keeping things tart. This will also aid the thickening ability of the starch, since sugar too can inhibit the thickening ability of starches.
Next issue, heat!
When I began tackling this pie as a girl, I would try to solve the loose filling problem by cooking the mixture longer, figuring it would reduce the excess moisture content in the filling. This isn't an unusual approach, as many recipes call for extended cooking times. Even my copy of Martha's Pies & Tarts requires a relatively lengthy boil for her classic lemon meringue pie filling.
Why would I question Martha, right? So I just continued to boil away.
Little did I know, this isn't a good idea. I realized, once I had brushed up on a little chemistry (thank you Essentials of Food Science), that starch has limits when it comes to heat.
Let me explain...
|What happens to starch granules as you heat them in liquid?|
When you heat a mixture of starch and water, water is able to enter the starch granules. These granules swell and reduces the free water in the mixture, components of the starch are then released into the mixture, changing the viscosity of the mixture and thickening it. Gravy 101 you're thinking, right?
However, did you know that if your mixture gets and stays too hot, your starch granules can "implode" releasing their liquid back into the mixture and reducing the viscosity of your pie filling? Oh yea.
During cooking, if you vigorously stir or whisk those hot bloated starch granules it can also cause them to burst. Continuing to stir after removed from heat is also ill advised. The amylose released from the starch granules will be doing the final job of setting the pie filling. To do this it is forming a fragile network structure between the granules to gel and trapping the remaining liquid. This isn't the most forgiving network and stirring the filling as it cools will destroy the nice firm silky texture we want.
I'm trying to keep this reasonably simple. Still with me? Groovy.
So now we all know that the acid and sugar, while delicious, need to be minded in relation to the starch. Fats too, to a certain extent, since we don't want to waterproof the starch granules (even if tossing a pat of butter into the mix does make the filling more luscious). We also know that we shouldn't subject the starch to searing heat or pummel our gelling mixture during the process with vigorous stirring or whisking.
Got it? Alright, let's craft a pie recipe.
The marvelously simple cooking/tempering technique I owe to the retired chef and author of Cookfoodgood.com. It works perfectly.
Not So Humble Lemon Meringue Pie
yields one 9" pie
1 9" baked pie crust. (Brush the crust with lightly beaten egg white during the last five minuets of baking to seal it.)
1 cup plus one tablespoon granulated sugar
2/3 cup cold water
1/2 cup corn starch
3/4 cup lemon juice
2 teaspoons finely grated lemon zest (almost two lemons)
4 large egg yolks
pinch kosher salt
1 1/4 cups boiling water
4 large fresh egg whites, room temperature
1 tablespoon of cornstarch
1/4 cup water
1/2 cup sugar
1/2 teaspoon cream of tartar*
Cake crumbs, cake donut crumbs or bread crumbs (optional)
*omit if beating in a copper bowl.
In a medium heavy bottom sauce pan, combine all the ingredients for the filling with the exception of the boiling water. Whisk until starch has dissolved and the mixture is thoroughly combined.
Whisk in the boiling water and then place the sauce pan over medium-high heat. Bring the mixture to a boil stirring gently with a silicone spatula or wooden spoon. Then reduce heat to medium-low and cook for up to one minute and no longer, continuing to stir gently. (I pull the mixture off the heat at 155°F, however if you do not have or wish to use a thermometer the "up to one minute" rule will keep you within the gelatinization temperature range for this starch.)
Immediately pour the filling into your prepared pie crust. If doing a hot filling meringue* immediately top with your pre-prepared meringue and bake according to the instructions below. If opting for a cold filling*, allow the filling to cool completely and then transfer to the refrigerator.
*info and instructions provided below after a lengthy meringue discussion detour
Now, let's take a minute to talk meringue. I realize meringue can be a thorn in the side of many home bakers. Poorly made, it wrecks cakes, macarons, and soufflés before they even hit the ovens. Unfortunately, on pies like these, they can be even less cooperative.
Barely cooked, the soft French meringues we typically slather lemon meringue pies with are pretty unstable. If poorly made, or just given enough time, the structure that makes up the meringue will break down and this will allow for the release of moisture and sugar. This is the weeping that smothers your pie with sticky ichor.
It will happen to the best of us, hence the short shelf life (roughly one day) of French meringue topped pies.
There are ways to minimize weeping, a few tricks and tips. And obviously, a well made meringue will hold up longer and weep less than a poorly made meringue, so execution is important. Unfortunately there isn't much consensus on HOW to make a meringue perfectly for a pie.
Specifically, I'm referring to the hot filling/cold filling lemon meringue pie debate.
Some feel that a piping hot filling is the best method, as it provides heat to the bottom of the meringue while the heat from the oven cooks the top. This does make sense, since heat will help set the proteins and this buys you time when it comes to weeping. Still, by the time the pie fully cools, there is usually a little weeping to contend with. A sprinkling of cake crumbs between the filling and the meringue helps absorb this moisture. It does work and I do use this method. However with mile-high meringues, it can be difficult to ensure adequate heat throughout and by the time your filling cools enough to serve you may find yourself with a bit more moisture than desired.
Others feel that the meringue is best put onto a chilled pie. Simply top the chilled pie with meringue right before serving, bake and then slice and serve at its structural zenith. Basically avoiding the whole weeping business all together. This is probably the easiest means of avoiding weeping for this particular pie.
I will instruct you on how to do both, since I use both depending on my whims and when I am going to serve the pie. (I will note that the pie slice staged for most of this post was a meringue slathered on a cold filling.).
However neither of these methods will save you from the headache of weeping if you attempt to store the pie for long periods or make the meringue poorly. Under beaten or over beaten/broken meringues cannot maintain their structure or hold onto their moisture.
Before I get to that though, I will mention there is also the option of using a cooked syrup meringue like Italian, which will hold up better (and longer) with minimal weeping but one exchanges the lightness of the French meringue for a more marshmallow-like meringue.
(Italian meringue is also an option for those who are leery of eating undercooked egg whites.)
|Pie topped with Italian Meringue|
Stable, but incredibly sweet as it usually requires twice the sugar.
I prefer the etherial quality of French meringue on top of my pies and am willing to deal with the limitations that come with it.
Let's get down to making a French meringue for this pie.
I always use a cornstarch infused meringue. It seems sturdier, less prone to weeping and comes with the added bonus of a silky mouth feel and cleaner cuts. I also employ cake crumbs here (usually from a plain, unglazed cake donut) to catching any rogue moisture ensure a dry seal between my pie filling and meringue. This, in addition to 'sealing' the meringue to the crust before baking helps prevent the meringue from slipping off the top of the pie when serving.
Preheat your oven to 350°F and set a rack near the bottom of your oven.
Combine the cornstarch and water and then place over medium high heat stirring constantly until it has thickened into a gel (about two minutes) and set aside.
In a large bowl, lightly beat the egg whites and cream of tartar to dissolve. Begin beating on medium-low speed until foamy and begin slowly sprinkling the sugar in while beating, giving the sugar time to dissolve (this is very important). Continue to beat on medium speed until stiff glossy peaks form. Then add the corn starch gel and beat to combine.
Sprinkle either your chilled or freshly poured piping hot pie with crumbs (if using) and then apply a large dollop of meringue. Spread the meringue to the edges of the pie, taking care not to disturb the crumbs. Seal the pie completely by pressing the meringue against the crust. Add the remaining meringue and fluff (or smooth) with a spatula in such a way that pleases your own personal aesthetics.
Bake the pie for 12-15 minutes until golden brown. Do not over cook as this will cause beading on the top of your pie.
For the chilled filling pie, allow the pie to stand for 15 minutes before cutting (using a clean damp knife) and serving. For the hot filling method, place the pie on a wire rack and allow to cool to room temperature before serving.
Okay, so maybe not my magnum opus (just really long), but not bad for a woman waddling about her kitchen in her 9th month of pregnancy. We only have one more week until the arrival of the littlest Humble!