Amazing meringue topiary.
Not the dance, that’s merengue, which has plenty of chemistry, too. This concerns that delicious sweet fluff that tops your lemon meringue pie or the lightweight candy sold at bake sales. It’s made by beating egg whites into a foam, which can then be cooked. But getting it right is tricky…
It may help to know the scientific reasons it might not turn out they way you expected. Smithsonian’s Food and Think blog tells you all about the meringue that went wrong.
Although egg whites are 90 percent water, the relevant molecules are protein. Proteins are made up of amino acids, some that are attracted to water, others that are repelled by water. One you start beating the whites and introducing air, the water-loving bits cling to the water, the water-repelling bits cling to the air. The more you beat, the more bubbles with a protein coating are created and the more the whole shebang fluffs up. However, bubbles and proteins divided against themselves will not stand, and the foam will collapse without a little stabilizer. One way of doing this is to introduce an acid such as vinegar, lemon juice or cream of tartar, which encourages the proteins in the egg white to bond together. Another ingredient that adds structural integrity, in addition to providing flavor, is sugar, which works like a glue that holds the foam together.
But why don’t we want to use the yolk? This part of the egg contains fat, which interferes with how the proteins line up and coat all those bubbles that are supposed to bulk up your meringue. If the bubbles aren’t properly protected, your meringue will never have much body. This is also why chefs are discouraged from using plastic bowls for this purpose as they have a tendency to retain oils.