swelling cooked egg white mousses. The significant rising of the souffle and the meringue is primarily
due to the substantial amount of water in the preparation evaporating. Water evaporating greatly
expands the mixture. The increasing pressure due to the increase in gas content increase is tolerated
by the rather delicate protein network because the ovalbumine proteins in the egg, which are not
denatured by whisking, denature on heating, and will contribute to the network surrounding the
incorporated bubbles, strengthening it.
On cooling, a souffle will tend to fall. This is because on removing from the heat source, the gases will
contract and any water vapour present will condense. Because souffles are only cooked for a short
amount of time, the protein network is not as rigid as in a meringue (which is cooked at a higher
temperature for longer), so will not hold its shape as the gases contract. In a meringue however, the
protein network is sufficiently rigid that it will keep its swollen shape even if the gases contract.
Souffles should be baked rather than grilled:
As a souffle is placed in the bottom of an oven, the bottom of the dish heats up the most rapidly, and
this causes the liquid at the bottom of the dish to evaporate. These bubbles of water vapour rise (due
to their lower density) and this lifts up the layers of souffle above it, and eventually the gas leaves by
the upper surface.
However, not all the water vapour...
the upper surface.
However, not all the water vapour will escape – once the temperature at the surface of the souffle is
sufficiently high, rapid protein coagulation and complete water evaporation will allow the formation of a
hard crust at the surface, which will prevent further water vapour or gases from expanding. Souffles
should always be cooked from the bottom (i.e. baked) because if they were heated from the top, i.e.
grilled, the water would vaporise first in the upper layers, and since gases rise rather than sink, this
evaporation of water would not let the souffle rise.
Importance of oven temperature:
In order to maximise the rising of souffles, the speed at which the protein network strengthens should