The Science of Eggs: Eggcellent Facts You Should Know
Is there any meal that can’t be made better by putting an egg on it? Well, maybe, but you get the point. Eggs are one of the most versatile (satisfying, hearty, delicious, the list goes on) ingredients to keep on hand. They can perform a variety of roles in the kitchen, apart from the quick pan scramble, and span all cuisines across the globe. In the past, we’ve written about deviled eggs and poached eggs, but now we’re getting down to business. What is it about the egg that makes it so perfect? The answer is all about science and the egg’s very distinct molecular composition.
The culinary functionality of an egg comes from the unique differences between the yolk and the white. You probably have an idea of these differences if you’ve ever ordered an egg-white omelet to avoid the extra fat and cholesterol. The egg white, otherwise known as the egg albumin, is made up of entirely water and protein. The egg yolk, on the other hand, is rich in vitamins, minerals, fat, and a small amount of protein. Both delicious, both important. These compositional differences help to explain how the egg can perform so many diverse roles in a meal.
Let’s talk about the egg yolk first. The yolk is mainly used as a natural emulsifier, with help from a compound called Lecithin, which is a fatty substance that contributes to that silky, mouth-feel of an egg yolk, and aids in binding. The yolk holds water and oil together in mayonnaise, custards, and many other sauces (hollandaise, béarnaise) transforming two previously immiscible liquids into a lustrous, thick sauce. If you’ve ever wondered why certain yolks are darker than others, it’s because the color reflects the type of feed the chicken eats. A feed richer in carotenoids will give you that deep, orange hue.
Now, the egg white. The white is used to foam and leaven foods. When air is incorporated into egg whites, they can expand up to 7–8 times their original volume. The protein in egg whites help keep the egg stable when whipped, providing strength and integrity to many of your favorite baked goods (like meringues and macarons, to name a few). If even when one, tiny drop of yolk mixes into the white, the fat within can disrupt the protein matrix of the egg white and it will no longer create that fluffy, airy foam.
Because the egg yolk and white composition are so contrasting, they will thicken at different temperatures. The high fat content in an egg yolk delays the cooking time; this is why you can fry an egg and have a runny egg yolk and a cooked white (ugh, the sunny side up struggle).
One more plus? Eggs can last for a fairly long time in the fridge, but not forever! To check if your egg is still fresh, crack it onto a plate and look at the yolk. If it’s fresh, the yolk will create a dome-like shape. If old, the yolk will spread out and flatten slightly.
If you learn anything about eggs from this article, it’s that they are an epic kitchen tool and weapon. Yolks, whites, the whole egg… possibilities are pretty much endless with this perfect food. Now, take this newly-learned science, buy some eggs, and start cooking.
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