Recipes engineered for perfection—what exactly does that mean? The Science series takes you inside the experiments behind 50 cooking concepts featured in our new book, The Science of Good Cooking, by the editors of Cook’s Illustrated.
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Scrambled eggs should be a dreamy mound of big, soft, wobbling curds. They should be cooked enough to hold their shape when cut but soft enough to eat with a spoon. An omelet, on the other hand, must be firm enough to roll or fold, but the eggs should still be tender and soft. Unfortunately, all too often BOTH dishes turn out dry, tough, or rubbery. Sometimes this is due to overcooking. But no matter how much you cook the eggs, they need some help to keep them tender. The magic ingredient? Fat.
The Backstory
First, let’s talk about what happens to eggs when you cook them. To understand what’s really happening, you have to start with the notion that eggs actually contain distinct elements—the whites and the yolks—that behave quite differently.
The whites are 88 percent water, 11 percent protein, and 1 percent minerals and carbohydrates. The yolks are 50 percent water, 34 percent lipids, and 16 percent protein. When eggs are heated, the water turns to steam. The protein strands begin to unfold, sticking to each other, and eventually forming a latticed network. The formation of this lattice gel is called coagulation—the transition from liquid to a semisolid that you can pick up with a fork.
Ideally, the denaturing proteins will form a loose network that is capable of holding on to the water in the eggs, which will make the cooked eggs tender and fluffy. But it’s too easy for the proteins to form very tight bonds with each other, squeezing out too much liquid in the process. Here’s where the fat comes in.
Scrambled egg recipes generally call for some sort of dairy like milk. The fat in milk coats the proteins and slows down the coagulation process. The water in the milk provides additional moisture, helping to keep the eggs tender. (The liquid also produces steam, making fluffier and lighter scrambled eggs.)
