why does the souffle rise?

last few weeks, i spent a good amount of time studying the physics behind the rising of souffles for my aph225 final project. it was fun, and there were actually some "surprising" results!

"... most souffle recipes suggest beating the egg until it is “stiff”, but over-beating should be avoided. the definition of stiffness remains ambiguous. it is thus of my interest, both as an amateur chef and a phd candidate in engineering and applied sciences, to investigate the physics causing the rise of this delicate structure, with the ultimate goal of making a perfect soufflé."

it turns out that ideal gas expansion of the gas bubbles is not enough to explain the rise. water evaporation must take into account.

what does that imply about the optimal stiffness required? to find out, click here.


Some cool pics from the project:

the egg white must be stiff:


what the whipped egg white looks like under the microscope. the vertical bars are separated by 1mm:


finally, the rise: