Soufflé puffs up in the oven, but then it often collapses. Why?
To have the perfect soufflé you need to whisk the egg whites until they stand in peaks on the whisk. Tip the whites delicately on top of the mixture using a palette knife and mix quickly, place the mixture in a ramekin.
The oven must be very hot, about 200°C, so that heat will coagulate the proteins of whisked eggs. Meanwhile air bubbles – air incorporated during whisking – expand within the soufflé making steam evaporate.
When the proteins network is firm, it traps the gas within the mixture, so that the soufflé will rise as a leavened dough. Even a small breeze of cold air could make the soufflé collapse.
The air bubbles trapped in the egg whites expand upwards, the heat solidifies them and form a nice crusty top. At this point, the soufflé doesn’t collapse, even when the air at the bottom is cooler.
