Have you ever been left with egg whites after making a recipe that calls for egg yolks only? And not feeling like making crispy meringues from the oven, again? Good thing there are a lot of different types of meringue. Apart from the crispy variety, there are also meringues that a soft and shiny, such as this Italian meringue.
As a result, I recently decided on using those left over egg whites in my Italian meringue. It gave a smooth, sweet, but light, topping for a cheesecake I was making. I had made too much though, and a week later, the remainder of the meringue had completely collapsed. Fortunately, it was easy to revive and knowing some Italian meringue science will help you understand why!
Making Italian meringue
An Italian meringue is just one type of meringue. All meringues are made with an egg white foam and sugar to help stabilize that foam. Heat helps to stabilize the foam over time and the different types (such as Swiss and French) differ in how that heat is applied.
For the Italian meringue heat is added to the meringue by pouring in a boiling hot (121C) sugar syrup into your whipped egg whites. The high heat ‘cooks’ the egg whites and ensures the foam is sturdy enough to hold on to the air. The overall process is actually quite similar to making marshmallows.
Two types of sugar
In an Italian meringue recipe you may be asked to use two different types of sugar: granulated & powdered. There is a good reason for using the two.
You add the icing sugar to the egg whites themselves. Icing (or powdered) sugar is sugar that has been ground very finely into small crystals. As a result, it dissolves very quickly into the egg whites. This is great if you want to make a very smooth meringue. By dissolving, any graininess will disappear!
For the sugar syrup on the other hand you can use the rougher regular (granulated) sugar. You start out by dissolving the sugar in warm water anyhow. It doesn’t matter whether it has a larger particle size, the heat will ensure it dissolves well anyhow.
Science of an Italian meringue
If you are familiar with making foams from egg whites this process should look very familiar. You whip up egg whites until it’s nice and fluffy. During this whipping process air gets incorporated into the egg whites. Egg whites contain a lot of proteins. These proteins will sit around the air bubbles and prevent the air bubbles from coming together and thus collapsing.
Sugar helps stabilizing an egg white foam. The sugar will make the water (which sits in between the air bubbles) slightly more viscous and thus stronger. Of course, sugar also strongly influences the taste of the meringue.
Hot sugar syrup stabilizes
What really stabilizes an Italian meringue though, is the hot sugar syrup that you pour over. Because of the sugar syrup being so hot, well above 100C, it immediately cooks the proteins. As a result, they unfold and become even better at stabilizing the air inside. At the same time, the sugar syrup also adds some extra moisture, which ensures that even though you’re cooking the meringue, you’re not drying it out. Instead, you’re making it softer.
Hot sugar syrup kills
The sugar syrup doesn’t just stabilize the meringue. It is also a great way to kill any micro organisms that might be present in the egg whites. This way, your egg whites aren’t raw anymore and they’re safe to eat.
Saving a collapsed Italian meringue
What’s special about the Italian meringue is that it’s quite a stable foam, however, it is not as stable as a meringue that has been baked in the oven. So it will actually collapse slowly over time, which is exactly what happened after I left it in the fridge for a week.
An Italian meringue will probably have some denatured proteins, however, by far not all proteins will have denatured. This means though that even though the meringue might collapse over time since the air bubbles slowly leave, you can restore this by whipping it up again!
So the trick to revive the Italian meringue is actually really simple: Put your Italian meringue in a stand mixer and turn on the whip on a high speed. Don’t worry if the meringue collapses at first. Whipping it will actually take out all the air that’s still in there! Just keep on whipping at this point in time, after 5-10 minutes you will see it coming up again. You will have restructured all the proteins around the freshly made air bubbles and it will stay stable for a couple of days again.
Problem solved! No need to throw out this smooth delicacy, just add it to your pie again.
What’s in the name?
Besides Italian meringue there are two other main types: French & Swiss meringue. They’re all made of sugar and egg whites, the differences sits in the way the sugar is heated. French meringue doesn’t use any heated sugar, it is actually the basis of my Dutch schuimpjes. Swiss meringues are made by heating the sugar and egg whites together over a double boiler. I’m not sure where the names come from, but it seems as if Europeans quite liked meringues!
- 160g granulated sugar
- approx 50g water
- 4 egg whites
- 35g icing sugar
- Add the granulated sugar and water to a pan and bring to the boil. Ensure all the sugar dissolves.
- Continue boiling until the solution has reached a temperature of 121C. It is important that you monitor this temperature closely. The final boiling temperature will strongly influence the structure of your meringue.
- Whip up the egg whites (in a stand mixer is easiest) until you've got a fluffy foam. Add the icing sugar and continue whipping. The icing sugar will allow you to expand the foam even more and create a more stable foam.
- Once the sugar has reached the correct temperature (121C), slowly pour it into the whipped egg whites while continuously beating the egg whites (this is where the stand mixer comes in handy!).
- Keep on beating until the foam has cooled down to room temperature.
- The meringue is now ready to use.