My latest piece over at Lucky Peach is filled with very graphic information about making meringue. I feel like it should come with a warning label, since even I started to get cross eyed after writing the word “denatured protein” for the umteenthousandth time.
My friend Marc Shermerhorn took one of my baking classes and chose the recipe with the fewest ingredients, thinking it would be the simplest. Instead, he discovered that the recipes with the fewest ingredients are often the most complicated, because they rely on the precise interaction of the few ingredients involved. Meringue is right up Marc’s alley, with little more than egg whites and sugar. However, the way we combine them dictates the ultimate texture, and I’ve got every detail covered for you guys.
The kind of meringue you get from a bakery—the impossibly light cookie, so brittle that it crackles at first bite and dissolves immediately, leaving behind only an echo of flavor—is just one version of what “meringue” is. Meringue, whipped egg whites and sugar, is one of the most fundamental techniques in pastry. It’s the base for desserts like soufflés, mousses, semifreddos, marshmallows, chiffon cakes, and some cookies, to name just a few. As such, it is crucial for a pastry chef to master—and is a useful technique for every home cook to have in his or her arsenal.
First, some science. There are three generally observable states of matter in the physical world: liquids, solids, and gases. Meringue is a foam, which forms when a gas is suspended in a liquid or solid.
Combining states of matter is not particularly difficult, but encouraging them to stay combined is. When creating a stable foam, two things need to be present: a foaming agent, which traps the air, and a stabilizing agent, which keeps the air in place. In a meringue, albumen, the family of proteins in egg whites, acts as the foaming agent. Albumen has dual-action surfaces. Some elements are hydrophilic, meaning they love water, and others are hydrophobic, meaning they fear water and will grab onto anything else present to avoid coming in contact with it. When the egg whites are whipped, the hydrophobic parts of the proteins search for air, seeking refuge from water. When enough proteins cluster around an air bubble, hiding their hydrophobic parts inside it, the bubble will become completely surrounded by proteins, and in turn, trapped.
Though the hydrophobic parts of the albumen have trapped an air bubble, the hydrophilic parts are attracting water. The proteins themselves aren’t durable enough to hold the heavy water molecule steady and keep their hydrophobic parts inside an air bubble at the same time. Think of the proteins like little teeter-totters with a water balloon on one side, and a balloon filled with air on the other. If you’ve ever whipped plain egg whites, you’ll know that they will begin to deflate almost immediately after you stop the motion of the whisk.
This is why we need a stabilizing agent, and in meringue, we use sugar. The sucrose molecules act to stabilize the foam, bonding with the proteins and water, gluing everything in place and helping meringue holds it’s shape. If sugar is added incorrectly, however, it can act as a destabilizing agent, which brings us to the first tip to making a good meringue……
Add the sugar gradually
When sugar is added to egg whites, it begins to bond with the protein and water. However, it needs some time to dissolve from a sugar crystal into individual sucrose molecules, before each individual molecule can go to work. The key is to add the sugar in small increments, allowing a generous amount of time between additions to let it break down. I add two tablespoons at a time, with one minute between additions. A good meringue can take up to thirty minutes to make, but that’s less time than making and discarding ones that don’t work.
Use ultrafine sugar
In trying to dissolve sugar crystals, ultrafine sugar is your friend since the crystals are smaller. If you don’t have ultrafine sugar you can process granulated sugar in a food processor to reduce the size of the crystals. An added bonus: regular sugar crystals are heavy, and can tear through the delicate foam as they are added, partially deflating it. Lighter, finer sugar crystals reduce that risk.
Whip the egg whites to medium peaks before you add the sugar
If you add the sugar before the eggs are whipped into a foam, it will prematurely bond with the proteins and limit their ability to trap air. If this happens, your meringue will be dense like a marshmallow soup, if such a thing existed. To avoid this, whip the egg whites to full volume, trapping as much air as possible until they increase eight times their original size. Then, and only then, add your first small addition of ultrafine sugar.
Whip your egg whites at a medium speed
This is important for two reasons. First, by whipping on a medium speed, we incorporate medium sized air bubbles that are easier for the proteins to capture. At high speeds, the whip makes air bubbles too large for the proteins to fully cover. The weak foam will collapse as the large bubbles escapes. It’s tempting to want to turn the mixer to high speed to shorten the time it takes to create medium peaks, but resist this urge!
Second, if you look very closely at the proteins in egg whites, you’ll see they are long chains of tightly coiled amino acids. We want loose chains that can cross link and grab both water and air efficiently. Imagine a tangled necklace. In order to untangle it, slow and gentle pressure is best. If you tug on the chain in haste, the knot stay will stay put, eventually you’ll break the chain. The amino acids chains that make up the protein in egg whites function the same way. Slow whipping to gently coax them to change their nature, or “denature” is the solution. If you whip your egg whites quickly, the proteins unravel themselves haphazardly and break, leaving you with a weak structure prone to collapse. You won’t notice until it’s too late: egg whites go from soft peaks to dry and curdled instantaneously.
Add an acid to your egg whites
A small addition of acid (usually cream of tartar) helps denature the proteins, before we begin to whip the egg whites. Be warned: if you add too much acid you’ll either end up with a tart meringue, or worse, curdled meringue.
Adding acid directly improves stability by lowering the pH of your egg whites, thereby preventing a bond between the sulfurous ends of the amino acid chain in the egg white protein. This sulfur-sulfur bond squeezes water from the foam, resulting in crumbly, dry “over whipped” whites. A bonus: the added acid gives you a longer window of time between soft peaks and over-whipped. If you’ve ever heard that whipping meringue in a copper bowl improves it’s quality, you heard right. Copper also acts to disrupt the sulfur-sulfur bonding. It’s not a fail-safe; if you let your egg whites beat too long, even with an acid, you will eventually over whip your eggs.
Warm whites whip better than cold whites
Much like humans, protein in egg whites huddle up in cold temperatures. To encourage them to loosen up (denature), it’s best to bring them up to 75 F before whipping. You can do this by leaving them in a warm room or by stirring them over very low heat.
Do older whites whip better than newer whites?
If you’ve cracked a very fresh egg into a pan for breakfast, you’ve seen the tall white that surrounds the yolk like an emoji. Delicious! Now if you’ve cracked eggs that have been sitting in your refrigerator for a couple weeks, you’ve seen the white run wild in your pan, bleeding to the edges.
Which one do we want? The aged-egg white committee argues that time loosens the proteins makes them more willing to form a foam. The practice makes more sense for bakeries, where containers of egg whites are a common a by-product of separating yolks for other uses. At home, you can age your whites in a container in your refrigerator for a week, or use the oldest eggs you have in there (so long as they aren’t spoiled—be safe y’all).
Fresh-egg defenders that argue the proteins are strongest when the egg whites are freshest. Likewise, the pH of an egg white rises as it ages, becoming less acidic over time, therefor offering more of acids stabilizing effect the fresher it is.
So is aging your egg whites worth it at home? That’s up to you. In my own observations, aged egg whites foam much quicker and meringues can reach completion in half the time. As to the over all stability once the meringue is finished whipping? There’s not much of a difference.
Fat will deflate your meringue
This is not an optional improvement to your meringue technique, like aging egg whites. This is a deal breaker. The presence of fat will destroy your chances of whipping egg whites. If you’ve ever whipped egg whites and seen them form an opaque flat puddle, you’ve seen the effects fat has on the capture of air cells. This happens for two reasons.
First, back in this post about piecrusts (link), we talked a lot about shortening gluten chains. Now you remember, gluten is also a protein, just like our egg whites. While we wanted fat to hinder the bonding of proteins in piecrust, we really, really don’t want fat to do that to our meringue. Even what seems like a harmless drop or two of egg yolk in your bowl is enough to interfere with the protein bonding and cause complete collapse of the delicate foam.
Second, consider whipped cream. You’ll know fat also wants to form a foam. So much so that it competes with the protein for a chance to trap an air bubble. In doing so, fat pushes protein out of the way, completely ruining the chance for either the protein or fat to hold an air bubble. You know that kid at recess who got pushy and ruined the game for every one? That’s fat in a meringue. Just a few drops and suddenly no one gets to play.
Detergent will also deflate a meringue
Detergent wants to foam. It’s like fat in that way: it want to foam so much that it push the protein off an air bubble with military efficiency. So, when you wash your bowl and whip, make sure to rinse thoroughly.
Are you still with me? I know, that’s a lot to take in. But I’ll make it simple for you. To apply this long list of details, you’re going to make your meringue something like this.
- Measure clean egg whites with no trace of yolk into a washed and well-rinsed mixing bowl.
- Let the eggs come to room temperature, either by leaving the bowl on the counter for two hours, or by applying gentle heat watchfully for a few minutes, careful monitoring the temperature with a thermometer.
- Add a small amount of cream of tartar and begin whipping your egg whites at a medium low speed, leaving them alone for about 5 minutes.
- Once you see your egg whites are holding medium peaks add two spoons of ultrafine sugar. Wait a full minute before you add another two spoons of sugar, and continue waiting and adding sugar until all the sugar has been added.
- When all the sugar is added, whip the meringue for 2 more minutes, then stop the mixer, dip the whip into the bowl and extract it, marveling at the luxurious glossy peaks that are drawn from the bowl. If your eggs aren’t completely whipped, continue whipping at medium speed until they are. Now, use your perfectly whipped, stable meringue immediately!
If all this seems daunting, remember, there are two hard rules—no detergent and no fat—and then there are six details that will help orient the ingredients in your meringue towards optimal texture. If you keep these details in mind while you perform the simple act of whipping egg whites with sugar, you will be greatly rewarded all your meringue applications.