08/18/2024
We did a research article into common problems with meringue. Meringues:
If the transformation of eggs by heat seems remarkable, consider what beating can do! Physical agitation normally breaks down and destroys structure, but beat eggs and you create structure. Begin with a single dense, sticky egg white, work it with a whisk, and within a few minutes you have a cupful of snowy white meringue. A cohesive structure that clings to the bowl when you turn it upside down, and holds its own when mixed and cooked. Thanks to egg whites we’re able to harvest the air, and make it an integral part of meringues and mousses.
With all the trouble creating a meringue we can sometimes forget how marvelous the egg really is. Remember the slogan, “The incredible edible egg.” Literally they are miracles in a shell. Almost all the questions presented ask about the pesky weeping problems with meringue. I spent some time going over my notes and a few resources so I hope this helps in the understanding of why meringues weep and how to keep them stable.
So many times you will need to read a whole article to get to the highlights or pro tips. We are going to list them now. Avoid any type of fat, especially egg yolk. Even fat leftover in a bowl will kill your meringue. Use glass or metal freshly cleaned bowls wiped with vinegar. Plastic bowls can retain fat even after bring washed, avoid using plastic bowls. Add your acid at the beginning of whipping, add your sugar after the egg whites have begun to foam. Adding a starch or gelatin with the sugar will help to control liquid. Place the meringue on a hot filling and bake in a low and slow oven, temps between 275 and 325 degrees.
Let us get started, what do you do about the water weeping? We will review the steps that have a tendency to cause the most problems and offer solutions. It will help to understand a bit about the science of how an egg white transforms into a foam or meringue.
Egg whites are 90% water, which alone should give you an idea why it is so hard to control the weeping. The other 10% are an assortment of proteins and other elements. Here are the three main proteins and one small protein that do most of the work in creating a meringue. It doesn’t matter if you, or I, can pronounce them; we just need to know how to put them to work in our meringue.
Percentage of the 10% of the egg white that is not water:
Ovalbumin 54% - is resistant to the whipping but is sensitive to heating. When the meringue is heated this protein more than doubles the solid protein reinforcement in the bubble walls. At the same time, much of the free water in the meringue evaporates. Heating thus allows this component of the meringue to transform from a transient semi liquid foam into a permanent solid foam.
Ovotransferrin 12% - is the protein that allows the egg white to foam. It attracts the water and the air during whipping.
Ovomucoid 14% - is heat resistant and helps the bubble wall structure within the foam.
Ovomucin 2% - this protein is the glue that holds most everything together.
These 4 proteins play a delicate dance in helping to create meringue foam. To make the foam, Ovotransferrin protein needs stress from the whipping action, but too much stress will break the foam down to a watery mess. Do not whip the eggs past a stiff peak stage but I am jumping ahead of a few important steps. Stress alone can make foam but there are ways to help the egg whites. Adding an acid, a starch or gelatin, sugar, and using a squeaky-clean glass or metal bowl can add to the stability of the egg foam.
Glass or metal bowls are better than plastic because one thing that can inhibit foam development is oil and fat. Plastic has a tendency to retain oil and fats even after washing. Squeaky-clean glass or metal bowls will give you the base environment to create a good meringue. After washing your bowl wipe the bowl out with vinegar, this will clean out any missed oils. Vinegar is also an acid.
Why are we asked to add an acid to egg whites for meringue, most commonly lemon juice or Cream of Tartar? Why and how does cream of tartar increase the volume and stability of our meringue? A little acid helps control the hydrogen and sulfur molecules that are the key to gaining meringue volume. A little acid will help, a lot. Sulfur-sulfur (S-S) bonds form when the sulfur-hydrogen (S-H) groups on two different protein molecules shed their hydrogen molecule causing a sulfur-sulfur (S-S) connection with each other. Sulfur-sulfur bonds slow the development and volume of the meringue. By preventing as many sulfur-sulfur (S-S) bonds as possible, the greater the volume of foam you will have. The addition of an acid boosts the number of free-floating hydrogen (H) ions in the egg whites, which makes it much harder for the S-H groups to shed their own H molecule, and so slows the sulfur bonding down to a crawl. A good dose is 1 ⁄8 teaspoon/0.5g cream of tartar or 1 ⁄2 teaspoon/2ml lemon juice per egg white, added at the beginning of the beating. It is important to add the acid at the very beginning of the whipping of the egg whites.
Sugar both hinders and helps meringue making. Added early in the process, it delays foaming, and it reduces the foam’s ultimate volume and lightness. The reduction in foam comes from the sugar’s interference with the unfolding and bonding of the egg white proteins.
Sugar is usually incorporated into the meringue after the egg whites have begun to foam, when many proteins are already unfolding. The helpful thing about sugar is that when added at the right time it improves the meringue’s stability. By slowly adding in the sugar, 2 tablespoons per egg white, after the egg whites have begun to foam the sugar greatly slows drainage of liquid from the bubble walls helping to reinforce their structure. In the oven, the dissolved sugar hangs onto the water molecules and so delays their evaporation in the heat until after Ovalbumin has had time to coagulate and reinforce the meringue’s bubble structure. Very fine sugar works better than regular sugar. The finer sugar dissolves better. This is also where baking low and slow helps by allowing the bubble wall structure to develop and evaporate as much of the water as we can. We will visit about weeping and oven temp shortly.
Adding cornstarch or a gelatin will help control any water that does not evaporate. Heat a combination of water and cornstarch on the stove, heating and stirring until the mixture turns clear. Let the mixture cool and add it slowly to the meringue with your sugar. You can also add clear gelatin or a modified cornstarch such as brand Instant Clear-Jel and Regular Clear-Jel. Gelatin and Instant Clear-Jel should be added with the sugar. Regular Clear-Jel should be prepared as cornstarch.
An oven temp between 275 and 325 works well. Personally, I have good success at 300 degrees. The goal is to bake the meringue top, middle and bottom at the same time. Placing the meringue on a hot filling will help the bottom and a cooler oven will help not to over bake the top. I have read some suggest a hot oven of 400 degrees to quickly brown the meringue. Unless you are making a Baked Alaska, I don’t recommend the high temperature. If the top over-bakes, the egg white proteins that build the bubble wall structure coagulate to quickly not allowing the water to evaporate causing weeping on top of your meringue. Similar weeping problems happen on the bottom and the middle of the meringue when it does not finish baking properly. By not allowing the protein Ovalbumin to properly coagulate slowly and allowing the water to evaporate you will get water build up between the meringue and filling and beading on top of the meringue.
Moisture is all around us. Humidly will affect your meringue, sugar naturally attracts moisture so the sugar we use in the meringue will eventually draw moisture to it. Even with taking all the precautions to dry out your meringue, it inevitably will attract moisture to it. It would be best to enjoy your pie same day or the next.
This article is about regular or French meringue but I would like to note two other popular meringue options. Swiss meringue is prepared by gently heating egg whites and sugar in a pan that sits above boiling water, without touching it. When the mixture reaches 120 to 130 degrees and the sugar is completely dissolved, the mixture is pulled off the heat and beaten vigorously to increase and attain full volume. Then beaten at a lower speed until cool and very stiff. Swiss meringue is smoother, silkier, and somewhat denser than French meringue and can often be used as a base for buttercream frostings.
Italian meringue is made by drizzling 240-degree sugar syrup into whites that have already been whipped to hold firm peaks. Whipping continues until the meringue is fully voluminous, satiny, stiff, and cool. Italian meringue is often used to frost cakes (alone or as a base for buttercream frostings), to top filled pies, or to lighten ice creams, sorbets, and mousses. When either Swiss or Italian meringue is used for pie some of the cooking of the meringue and evaporating of the moisture is done by heating the meringue mixture or pouring hot sugar into the fluffed egg whites.
Meringue highlights: No fat especially no egg yolk, fat will kill your meringue. Squeaky-clean glass or metal bowls, plastic bowls can retain fat. Add your acid at the beginning of whipping, add your sugar after the egg whites have begun to foam. Adding a starch or gelatin with the sugar will help to control liquid. Place the meringue on a hot filling and bake in a low and slow oven, temps between 275 and 325 degrees. Enjoy your pie within a day or two.
In researching this project I would to acknowledge gathering information for this article from my own experiences, American Test Kitchen, The Pie Book by Louis P. De Gouy, Professional Baking by Wayne Gisslen, Let’s Talk Science web site, On Food and Cooking by Harold McGee and a number of sources not noted but used for cross checking information. This is meant for help readers create wonderful meringues.
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