TIPS The secret of a successful meringue is producing a stable egg white foam. The egg whites begin as a liquid which, as beaten, incorporates air, forming first in large bubbles, the frothy stage, then, in countless tiny air cells. The liquid has become a white foam, smooth and moist in appearance which, when the beaters are withdrawn, forms soft peaks and then after further beating, stiff peaks. Unless stabilized, the foam will return to its liquid state. This is why acid ingredients such as cream of tartar, vinegar, or lemon juice are added at the frothy stage.
Sugar also stabilizes the foam but, at the same time, it retards or slows down the foam formation.
Use a glass or metal bowl, plastic bowls can have a greasy film which can prevent foaming. Separate the eggs carefully while still cold. Be sure no yolk slips in with the white to interfere with the foam formation. Let egg whites stand at room temperature for about 20 minutes after separating. They will whip to a greater volume than if beaten when cold.