What causes a soufflé to get so tall?

A soufflé is generally a base — such as pastry creme, fruit puree, or béchamel — that has been lightened by folding several whipped and stiffened egg whites into it. The heat expands the air trapped inside while at the same time tightening the proteins in the egg white, causing it to rise upward, sometimes several inches. Fruit, cheese, or even chocolate can be added before folding in the egg whites for a delicate and delicious treat.

Asked by Leni Davenport · Last updated 5 years ago · 1.1M views · SOURCE