Chocolate Souffle Day

What the day is

Chocolate Souffle Day is observed on February 28. The name is the French word for blown, and the dish is a demonstration of one physical process.

Origin and background

A souffle contains no chemical leavening. What lifts it is the air beaten into the egg whites, expanding as it warms, and above all the water in the mixture turning to steam. Steam occupies vastly more volume than the liquid it came from, and trapped inside a foam it pushes the whole thing upward. Meanwhile the egg proteins coagulate and set into a structure that holds the shape.

The collapse follows from the same mechanism. Out of the oven the souffle cools, the steam condenses back to a tiny volume of water and the trapped air contracts, so the internal pressure holding it up disappears. The set protein network is not rigid enough to stand alone, and it sinks. A souffle falling is not a failure; it is the physics running in reverse, which is why the dish is served immediately and why restaurants time it to the table rather than the pass.

The rules around it all follow. Opening the oven early drops the temperature before the protein has set, so the structure deflates while still fluid and cannot recover. Greasing the ramekin in upward strokes and running a thumb around the inside rim gives the mixture a clean edge to climb rather than something to stick to, which is why a souffle sometimes rises lopsided. And folding rather than stirring preserves the air already beaten in, which is the entire reason for the whites.

Chocolate makes it harder. Cocoa solids and fat weigh the foam down, so a chocolate souffle rises less than a plain one and is less forgiving of over-mixing.

How to take part

• Grease the ramekin upward and clear the rim with a thumb.
• Fold gently and stop while streaks are still faintly visible.
• Do not open the oven, whatever the temptation.
• Have everyone seated before it comes out.
• Accept the collapse. It is supposed to do that.