Interpreting the Foam’s Appearance There are various ways to judge when the foam is at its optimum, from seeing whether the foam will support the weight of a coin or an egg, to seeing how it supports itself, in soft mounds or sharply defined peaks, to seeing whether it clings to the bowl or slips along its surface, whether its surface looks glossy or dry All these tests tell us how crowded the air bubbles are, and how much lubrication they have between them in the way of liquid from the egg white And different dishes will define an optimum foam differently The lightening power of an egg foam depends not just on the foam’s volume, but also on how easily it can be mixed with other ingredients, and how well it can accommodate bubble expansion in the oven Soufflés and cakes require the lubrication and expansion tolerance of a somewhat underbeaten foam, while in meringues and related pastries volume is less important than shape-holding stiffness Glossy Soft Peaks and Stiff Peaks At the “soft peak” stage, when glossy foam edges retain some shape but droop, and when the foam doesn’t yet cling to the bowl, the somewhat coarse bubbles are still lubricated by plenty of liquid, which would quickly drain to the bottom of the bowl At the “stiff peak” stage, where the foam is still glossy but now retains a well-defined edge and clings to the bowl, the foam is approaching 90% air, and the egg liquid has been spread so thin that the protein webs in adjacent bubble walls begin to catch on each other and on the bowl surface There’s just enough lubrication left for the foam to be creamy and easily mixed with other ingredients This stage, or perhaps just before it, is the optimum for making mousses, soufflés, sponge cakes, and similar dishes that involve mixing and further rising in the oven Further beating gains little additional volume Dry Peaks and Beyond Just past the stiff- ... air, and the egg liquid has been spread so thin that the protein webs in adjacent bubble walls begin to catch on each other and on the bowl surface There’s just enough lubrication left for the. .. by plenty of liquid, which would quickly drain to the bottom of the bowl At the “stiff peak” stage, where the foam is still glossy but now retains a well-defined edge and clings to the bowl, the foam...Glossy Soft Peaks and Stiff Peaks At the “soft peak” stage, when glossy foam edges retain some shape but droop, and when the foam doesn’t yet cling to the bowl, the somewhat coarse