Few recipes can compare with the elegant simplicity and heavenly goodness of a well-made meringue. Whether you enjoy it in the form of a macaron or served with fresh cream, whether you favour the Italian or French method, whether you prefer it soft or crisp, meringue will never lose its appeal, thanks to its salient characteristics of taste, voluptuousness and lightness.
However, as always happens when the discussion turns scientific, romanticism gives way to the cynical facts of chemistry: technically speaking, what makes meringues so nice?
To find out, the first thing we need to bear in mind is that meringue is substantially made of egg white and sugar.
Let's focus on the first ingredient.
Egg white consists of approximately 90% water and about 9% proteins. As we know, the latter are chains made up of many tiny elements, called amino acids, which are linked together. Amino acids are molecules belonging to different chemical groups, whose type determines whether they are hydrophilic (that is to say, they seek contact with water molecules) or hydrophobic (they shun water). When we whisk egg whites to make meringue, the proteins they contain are “denatured”, that is to say, they break up and rearrange themselves, either binding themselves to water molecules or preferring to keep away from water and bond with the air molecules incorporated during the whisking operation.
This is why ordinary egg white, which is in fact a liquid, turns into foam.
Of course, we have not yet considered the other protagonist of this fascinating story: sugar. In this case, there is no need to venture into complicated chemical explanations.
In most case, the sugar is sucrose, a molecule made up of fructose and glucose which, as we well know, is very soluble. And this is where the magic lies: as it dissolves in our foam, it will surround the micro bubbles of which the foam is made.
At this point, during cooking, the high temperature makes the water evaporate and, at the same time, triggers a reaction in the sugar, so that it caramelizes.
To simplify the concept a little, the water molecules “shape” the complex structure of the foam and the sugar builds a sort of scaffolding around it, after which the heat eliminates the former and cements the latter. These considerations pave the way to a myriad of excellent tips on how to achieve perfect meringues.
The secrets of a perfect meringue
First of all, it is necessary to have a correct ratio between egg white and sugar which, according to the experts, should be "one to two": one egg white, two spoonfuls of sugar.
Then, it is preferable to use icing sugar since it dissolves better and forms a more stable support.
The way in which the egg whites are whisked is also very important. The highest possible speed should be used in order to denature the proteins effectively.
Finally, watch your oven temperature, which also depends on the type of sugar you are using. Fructose, for example, which is widely used in cake-making, caramelizes at about 110 °C while sucrose does so at 160 °C.
This is why the ideal temperature for a perfect meringue using household sugar is around 175 °C, which strikes an excellent balance between the speed needed to usher out the water molecules and to obtain a perfect caramelization.
How to make meringue
Now you know everything there is to know about enjoying a good meringue. Whisk up an egg white (without the slightest trace of yolk in it) and when it forms stiff peaks of foam, gradually add two spoonfuls of icing sugar, mixing all the time.
If you want a meringue that is crisp on the outside with a soft centre, use this mixture for one single meringue and bake in an oven preheated to 175-180 °C for 15-18 minutes.
You are already drooling at the mouth, aren't you?