Most of us have probably observed the phenomenon of an egg white, once whipped, taking a fluffier, whiter, and more structured form, which is taken advantage of in many types of baking, from souffles to angel cakes, to waffles.
Confusing as to the precise language of the term “meringue,” Encyclopedia Britannica describes Meringue as a “mixture of stiffly beaten egg whites and sugar that is used in…desserts” [emphasis added], while many seem to use it to refer to the specific Meringue Cookie, the recipe we will be studying in this post, which is the meringue mixture basically piped into a cookie shape and baked to harden.
This is the most straight-forward dessert, regarding its simple and obvious use of egg whites, in my opinion, so that is why I will be using this form of meringue to explain the science in a basic manner. You will have probably used meringue or seen it used to top Lemon Meringue Pie. Whipped fluffy, then spread over the top, the meringue mix solidifies in the baking process in some sense, but keeps its soft and airy characteristics.
Meringue Cookies recipe – – – – PRINT
- You’ll want a low oven temperature so that you give plenty of time for all of the water to evaporate from the egg white before the tops brown too much.
- By beating the eggs, you are breaking apart the “building blocks” of protein, unraveling the amino acid chains. This is called denaturation. Unraveling the chains will give the egg white more surface area and structure, because, once separated from each other in long strands, the aminos will connect to form “networks,” which in turn trap the air bubbles. You’ll need to make sure that there is no moisture like water or grease in your bowl of egg whites, and of course no small bits of egg yolk. All of these things will interfere with the denaturation and prohibit peaks from ultimately forming in the way you need them to. Another thing that is helping the egg white to foam up is obviously lots of air. Air is getting trapped in the egg whites, expanding them, and the proteins are holding everything together.
- Even though the proteins are connecting together and structuring themselves, they have a tendency to fall apart after a lot of beating and whipping. In order to keep the proteins from falling apart from their networks of bubbles as easily, recipes such as this one call for you to add cream of tartar as a stabilizer which increases the acidity of the mixture, which aids the proteins by making it harder for them to collapse back to their original state.
- Egg whites can’t expand a great deal without added strength. By adding sugar you are adding strength. Why? Because the egg white proteins can “only expand so far” and so the way to give them more structure is by adding sugar, which bonds with the proteins and “lends them water.” This makes the whole thing a lot less likely to simply collapse, and gives it more potential for expanding and holding shape.
- When you apply the correct amount of heat for the correct amount of time, the water will evaporate and the air bubbles present in the egg whites will expand. At the same time, the proteins will all permanently bond together, or coagulate. For meringue cookies, all of the water should be cooked out, and the result should be much drier than meringue that tops pies, which is generally baked for a much shorter period of time than these cookies.
- If you leave them out of airtight containers, then the moisture in the air will eventually seep in and ruin the texture and structure.