To remove the yolk, tip the funnel into a small bowl. Sometimes whites have twisted strands of white known as the chalazae attached to the yolk. Remove the larger strands, called defeathering, as they will harden when heated in the oven or on top of the stove. After inspecting the whites to make sure they are free of shells and egg yolk specks, pour them into the third bowl. The coagulation of eggs is critical to many recipes.
Coagulation is simply the solidifying of the egg by heating.
A large portion of the discussion of stirred and baked custard hinges on egg coagulation. In many instances, the egg in a recipe will serve to glue the ingredient's together. When eggs are added to a mixture to thicken, sometimes the mixture is quite warm. If added directly, the mixture will cook the eggs. A technique called tempering is used when combining the two to avoid this problem.