Tuesday, December 15, 2009
One Word Wednesday . . . Meringue
As a Midwestern boy I grew up with exceptional pie bakers. My personal universe of pie was ruled by the triumvirate of: rhubarb pie (Mom's specialty #1), minced meat pie (Grandma's specialty), and lemon meringue pie (Mom's specialty #2). On a recent visit, my Mom treated us to her lemon meringue . . .
I love the fact that this pie is a balanced duet that includes both sweetness and acid, smooth filling and fluffy topping, egg yolks in the filling and a perfect place for the whites in the soft peaks of the meringue.
A meringue is a foam. The egg whites contain the protein albumin, which (in the absence of the oily yolks) can be whipped to incorporate air to form a light and stable foam. Proteins stabilize foams by going to the microscopic interface between air bubble and the watery continuous phase, unfolding, and forming a film. The cream of tartar (aka tartaric acid) helps facilitate this protein structuring and--while not absolutely essential--can help the foams reach their maximum volume. The sugar in the meringue thickens it by immobilizing some of the water, more sugar will result in a firmer foam.