Whenever studying something in science, or wherever else, you’d tend to start with a literature study. This sounds more boring than it is, it starts with browsing the internet, and when it concerns cooking/food, browsing cookbooks, blogs, etc. etc. It’s a great way to learn more about the thing you want to make.
Since I made a handy one-pager explaining the science behind eggs I decided to do a little more study into eggs. Finding ways to ‘prove’ the things I explained in that page. So one of the many things I came up with was ‘schuimpjes’ (this would be Meringue in English). Meringue is originally a French word, but it seems as if the English use it as well. The Dutch ‘Schuimpjes’ that I’m referring to is a baked version of meringue, even more simply said: a baked foam of egg white and sugar.
So I started my investigation with a ‘literature study’.
One of my favorite books for this type of ‘studies’ is Harold McGee’s On Food and Cooking. So I flipped it open to meringue, already discovering that there’s a whole lot of other types of meringues (Swiss, Italian, French, …)! Browsing blogs on the internet gave me a whole list of recipes, beautiful photos, colours, shapes, Jum!
Comparing Recipes and Ingredients
Blog and internet recipes combined with my cookbook recipes gave me a whole list of recipes for a meringue. I set out comparing the recipes to try to find the secret of a great meringue. The recurring ingredients I found in the recipes were: egg whites, sugar, lemon juice or cream of tartar, icing sugar, a flavouring and salt.
Of course, all recipes contain egg whites, that’s what kind of defines a meringue. All recipes call for whipping up the egg white. As you could learn in my egg infographic, egg white contains a lot of proteins. By introducing air to egg white a foam is made. By the shear force of whipping these proteins are organized to stabilize the foam.
So why use only egg whites and no yolks? Well, the main reason for that is the presence of fat in egg yolk. This fat will destabilize the foam, it will make it hard, probably even impossible to create a foam.
Unfortunately, the egg white proteins themselves are not strong enough to keep the structure stable for a long period of time. That’s where the sugar comes in. Sugar makes the liquid phase more viscous. Think of a thick sugar syrup, it flows less freely than pure water. This prevents the water from moving around less, and if the water moves less, the air bubbles get trapped longer, thus the structure is more stable!
Lemon juice as well as cream of tartar as added to stabilize your foam. They are both acids and lower the pH of your mixture. This promotes the proteins to unfold and stabilize your beautiful egg white foam.
So why would you add salt? Well, surely not to stabilize your foam. Salt will dissolve in the water and be present in the form of charged ions. These ions will interfere with the proteins, actually preventing them from unfolding! Main reason to use salt would be for flavour, but try to limit it.
The use of flavouring speaks for itself, its to make the meringue even more tasty. What is important when choosing a flavour is to use one that doesn’t destabilize the foam. Fats for instance wouldn’t work well, vanilla or coffee would work fine.
Last but not least, why use icing sugar? Simple, it dissolves better in water than regular sugar, making it easier to include in the foam. Furthermore, if you don’t dissolve all table sugar, it might make your meringue somewhat grainy.
This introduction to the ingredients should help you in understanding what role all the ingredients play in a meringue. However, I didn’t tell you yet how to actually make the meringue. Come back later to read all about the ratio of ingredients and a method to make these jummy crunchy sweet foams.
I’ve browsed and read quite a bit, here’s a scoop of my sources: Decoding Delicious – all about egg foams, On food and cooking from Harold McGee, an old cookbook at my parents place, De Banketbakker bij Cees Holtkamp, Exploratorium on egg foams, More in depth on salt in egg foams