Sooner or later, the moment arrives in the career of any sous-chef: amongst the clamour of pots and pans, the chef gives the order to prepare a delicious soufflé. An ominous silence falls over the kitchen, and suddenly the movements become slower, quieter – greater attention is paid to ingredients and temperature. Because behind the seemingly simple term, which derives from the French verb souffler (to blow), lies one of the most beloved delicacies on a menu, and one that is among the most challenging to prepare – one that can knock out even the most expert cook. And yet, even this ephemeral dish follows some simple laws of physics and chemistry. Learning them will help anyone to successfully pull of a perfect soufflé. How? Let’s first take a look at the ingredients.
A soufflé really has two basic ingredients: a cream, which for a savoury soufflé is usually made from béchamel, and beaten egg whites. The two must get combined together to form a mixture that is then poured into special moulds and then placed in the oven. This is when a law of physics comes in, in the form of evaporation. The composition first gets cooked externally, along the borders of the mould, trapping the water molecules from the steam from within. When the temperature rises, they seek a way out and the only way is upwards – the only part of the soufflé not confined by the mould. As the top of the soufflé bakes and becomes thicker, the molecules push harder and this is why the top rises. And here lies the crux of the issue: a proper soufflé is one that creates the most resistance for the steam molecules.
The secret to this is to beat the egg whites until they are very stiff, so they create a compact foam that serves as a barrier. Of course, this mustn’t become an insurmountable barrier, otherwise the soufflé will turn into the most precarious of disasters; it’s estimated that in the best soufflés, just 10% should still be trapped inside once the cooking has completed, which is enough to make the dish rise double or triple in height. Now that we’ve explained the matter scientifically, it’s time to reveal the soufflé recipe from the Guinness Book of World Records.
First, prepare the béchamel. As we heat a litre of milk, put 100 grams of butter in a small pot, let it melt, and add 100 grams of sifted flour, stirring constantly. When the mixture is smooth, turn of the heat and slowly add the warm milk, still stirring. Once the milk has been poured, return the pot over a low flame and stir until the sauce thickens. Turn off the heat, add salt and nutmeg. Only now, beat 7 egg whites until stiff. When done, add them to the béchamel delicately, a bit at a time.
The movement is important: it’s important not to stir in a circular fashion, but to “slide” the egg whites into the mixture. Then grease the moulds and pour the mixture in, placing them in the oven. And now comes the last, important, trick: before we begin baking at 190°-200°C, turn on the grill for a few minutes. This will help “reinforce” the top crust, making it more resistant to the interior steam pressure. And then begin baking: for small moulds, baking time should be about 12-13 minutes, but do keep an eye on what’s happening – without opening the oven, if at all possible. You’ll be amazed at the record-making soufflés that will come out of your oven… and so will your dinner guests!
Still interested in Food Science? Don't miss our focus on the Science of Sauces, the Science of Fried Eggs, and the Science of Meat: you'll find some gourmet tips to apply science and physics in your kitchen!