Runny Lemon Meringue Pie

I had the same problem today.  Earlier this week I made the same pie.  Before chilling it looked and tasted fine; but upon serving it separated into liquid under the meringue.  I also used a torch to brown my meringue.  Still, I cannot figure out what went wrong.  However, there are recipes that do not require cornstarch but require baking.  I will try these out the next time.

Too much heat and/or too much acid destroy the thickening power of corn starch.  If you want to know why the filling for lemon meringue thickened, but turned runny later -- that is ALWAYS the reason. 

In Gummy's case, too much acid.  She can make her pie more sour by using less sugar.  For you other two ladies, too much heat.  That's a matter of technique, not ingredients.

There's a "no fail" technique for making the lemon filling involving tempering.

Whisk your filling mixture off the heat in a saucepan, with 1/3 to 1/2 of the total water, cold.  Meanwhile bring the remaining water to the boil  When the water boils, whisk it into the mixture until fully combined.  Put the mixture on medium-high heat, stirring slowly and continuously with a wooden or heat proof "rubber" spoon until it boils.  Immediately, reduce heat to medium low and stir for exactly one minute, and remove from heat.  

It's a very simple technique, but you must pay attention and respond to the temps -- especially when the mixture comes to the boil.  If you answer the doorbell or phone, the pie will fail.  Out of spite, if for no other reason.  Inconsistency in the temps you set on your stove, and/or the way you handled the mix as it came to the boil are most likely the reasons your results are inconsistent.

The problem is certainly not the torch.  In fact, a torch is the gentlest way to handle meringue on top of this type of filling.  Using Swiss meringue to top an American lemon meringue didn't cause your filling to break.  More, you certainly do not have to make a baked filling for a successful lemon meringue pie.  You can make a good pie that way, surely; but it's a different pie. 

You'll get less separation, less shrinkage, and less weeping if you pour the filling into the shell when it's still hot, and cover with meringue when the filling is still warm.  If the weather's particularly humid, you may want to try sprinkling a little corn starch on top of the filling before covering it with meringue.

Hope this helps,

BDL

Too much acid, huh?  That explains it - the extra shot of triple sec.

Lemon juice is an acid and it tends to break down a starch, as does anything alcohol based.. I also believe the first recipe does not have enough corn starch to liquid ratio. Also try adding a little albumin powder to the fresh egg whites , this will act as a stabilizer and it will hold up without weeping. Could be you did not cook the starch enough or eggs did not have enough heat to set. Biggest enemy of this pie is age , the longer held the more separation of liquid to solids.

Based on other recipes I've seen recently, I would tend to agree with the Retired Chef.  The first recipe he references appears to have similar proportions to Emeril's recipe for the same dessert.  It is a massive recipe where he adjusts all the ingredients upward.  I would never make a lemon meringue pie that large.  Furthermore, although he uses lemoncello in his version, I will not use neither that nor triple sec again!

add more corn flour

It may be you've thought of this, but lemon extract or lemon zest,  I use both (and other flavors) in whipped cream, pie fillings and a touch in the crust believe it or not.

BDL & Others, I tried today substituting lime juice 1:1 for the lemon -- no further adjustments to recipe -- rendering "the other LMP".  Started to set, refrigerated for a couple hours after it cooled on the counter.  Cut into it & gushed into the empty space of the pie pan.  Luckily I had baked up some peach pie w/raspberry whipped cream to serve the masses as well.  Son who's usually all over complimenting my cooking said "DAD what HAPPENED?!?!?" Response: I don't know, Nick.  I will have to find out though and redeem myself!

My question is, is there anything ingredient-wise (lime vs. lemon) that may have caused this, or does it point more to technique?  

Thanks, Steve

Sjmilone, a lemon has slightly more acid in it than a lime does and not really that much to be honest, so it should not have been the reason your LMP did not set up. It had to be some part of your technique that failed. 

Cornstarch can be a fickle thing some times, and like the other chefs keep saying it doesn't like too much heat or acid and also over stirring once its bonded with the liquid. Food scientists tell us the best way to make LMP is to add the lemon juice "after"  the corn starch, other liquids and eggs have been thoroughly cooked and have slightly cooled.  

This is the way Alton Brown does it.

1. Whisk egg yolks in medium size mixing bowl and set aside. (That denatures the yolks and gets them ready )

2. In a medium saucepan, combine cornstarch, (cold ) water, sugar, and salt. Whisk to combine. Turn heat on "medium" and, stirring frequently, bring mixture to a boil. Boil for 1 minute (No More than that). Remove from heat and gradually, one whisk-full at a time, add hot mixture to egg yolks and stir until you have added at least half of the mixture (then mix in the rest).

3. Return egg mixture to saucepan, turn heat down to "low" and cook, stirring constantly, for 1 more minute.

4. "Remove" from heat and "gently" stir in butter, lemon juice, and zest until well combined.

Thanks for your reply, tasquah.  It's funny you should demonstrate using AB's technique, that is what I was attempting to follow in the first place.  Even remember commenting "what the heck is a whisk-full" when I was reading it.  Think I figured it out though, should have made the meringue before the filling.  Instructions said to top with meringue "while filling still hot" and by the time I made the meringue, the filling was barely tepid, so I reheated it, not giving a thought to the chemistry of the corn starch, nor the instruction about no more than a minute...  Live and learn.  Salvaged it though:  Turned it into a frozen margarita:  freeze the pie, torch the meringue just to soften a bit, sprinkle lightly with Black Hawaiian Sea Salt & chase with Tequila shots.

Herein lies your problem.

Eggs contain an enzyme (extra-large have more than large) that, over time, will destroy the network of starch strands that thicken a pudding. Cooking the egg/starch mixture at a boil for 2 minutes will kill this enzyme and your custard will remain thickened.

The same hold true for the process of making pastry cream. The tendency when making starch-thickened custards is to worry about curdling the eggs with too high a heat. That will happen if you don't stir it constantly with a whisk during the short boiling time. 

Alas, if you don't bring the temp up high enough to cook out the enzyme, runny custard will result.

Shirley Corriher explains this process and the science behind it very well in her book BakeWise.

Lpool,

     When you are making a Lemon meringue pie using a meringue (egg whites) as a topping you must bake the pie otherwise you would be serving raw eggs to people. It only takes a few minutes but is an important part of the process. To keep the meringue from separating from the pie after cooled and cut you should apply the meringue immediately after placing the filling into the crust. Then place in oven to cook the meringue and help seal things. When you take it out of the oven you need to let the pie sit at room temperature for approx. 1 hour before placing in the fridge (which also helps seal and reduce the possibility of the meringue leaving water droplets). After approx. 1 hour place it in fridge for approx. 5-6 hours before serving. As far as it being runny, it could be that you did NOT cook the custard long It must be thick enough before placing it in the crust. Also, be sure to blind bake (pre-bake before adding custard) your crust to keep it from getting soggy from the custard. Hopefully this helps somewhat. Also, I use milk instead of water cause it helps to keep it from being so runny and adds a wonderful smooth texture.

LPool, also, I forgot to mention that since you are using an italian meringue you cant possibly bake it but should adhere to all the other methods.