I thought that I would continue with a bit of a sciencey theme and talk about eggs. Not the most exciting topic I can hear you say, but then do you have a picture of a lovely crisp-on-the-outside-but-soft-on-the-inside Meringue? Can you picture it as a Pavlova, filled with fresh fruit and cream? Or individual, piped mini-meringues, sandwiched together with a smooth chocolate ganache? Or even that retro dessert Baked Alaska – soft sponge base, liqueur-soaked fruit, cold vanilla ice cream and covered in hot crisp meringue!!!! Delicious.
Of course, all this is due to science and knowing a bit about egg whites. Actually, similar processes go on with aquafaba as an egg-free substitute. Its all about the proteins and the pH. Who knew that the different amino acids (the basic building blocks) in proteins could have a positive or negative charge? This is how some of them join together to form long protein chains and how they behave in mixtures. It also means that they can be affected by changes in levels of acidity – something to bear in mind when making meringues.
Egg whites are basically protein and water. The proteins are in the form of long chains that are coiled up, just waiting for you and your whisk to come along and reform those coils into long chains that reform around air bubbles.
When you start, the air bubbles are quite large. Keep whisking, and they get smaller and the structure that is formed by the egg white proteins become more stable as it can form more connections around smaller bubbles. You can see this as you get from liquid to the soft peak, then firm peak stages. If you whisk too much, you break down these connections, the chains collapse and the meringue looks dry as all of the water in the egg white leaks out and the air escapes.
So, how to make great Meringue.
First, make sure that the equipment is big enough for all that air and that it has no traces of fat at all. Fat stops the proteins reforming into long enough chains to hold the air bubbles, even the fat from egg yolk.
Make sure your eggs are fresh and at room temperature. The best temperature for making meringue is 21°C. The purpose of egg white in the egg is to hold the yolk in place so that it can support the chick. Therefore, the consistency of a fresh egg white is thick. As the egg gets older, so the pH of the proteins changes and the egg white gets more alkaline (as the egg absorbs CO2), and therefore, thinner. This means that the meringue won’t hold as much air and is more likely to leak.
I always add a very little acid to my egg whites when making meringues. I have seen recipes that suggest that you wipe the inside of the bowl with a cut lemon to provide the acid. This works, as does adding a pinch of Cream of Tartar or half a dribble of white vinegar. Whatever your acid of choice, it need only be a very little amount to help your proteins break the chains and reform. Sugar helps to stabilise the foam, but you have to do a bit of whisking first to start the process. If you add it too soon, don’t worry, you just have to whisk a bit longer to get the right amount of aeration. I think that it is best to whisk to get some volume and small bubbles, then whisk in half of the sugar to get soft peaks and a gloss, then fold in the rest to taste. I never add the amount that lots of recipes say because I find it too sweet.
Now to cook. Egg white proteins set at between 60 and 65°C. so, they only need a low temperature to ‘dry out’. Gas 3 or 150°C is good and then cook till it is firm enough on the outside while still being soft on the inside to make the meringue that you want.
Happy Cooking. And more importantly, happy tasting.
Till next time