Wide Open: Swetha Sivakumar on cooking with eggs

Eggs can be a cook’s best friend in the kitchen and their biggest challenge. Making the perfect omelette is so difficult that it is often used as a test of a chef’s skills. It can take years to learn to reproduce the precise shape of a cigar and the silky yellow texture of a French omelette, removing all the brown spots and that eggy smell.


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A boiled or fried egg, on the other hand, is one of the first meals a child can prepare at home. Crack one over hot oil and you usually can’t go wrong.

How does this little orb manage to be both so simple and so complex? Let’s take a look.

An egg consists of two very different components. There are proteins that are 90% water and about 10% protein, with traces of minerals, vitamins and glucose. And the yolks, which are about 50% water, 34% fat, and 16% protein. By the way, the yolk is full of vitamins and minerals, including iron; basically everything you would need to raise a chick.

There are two key things to understand when it comes to cooking an egg. The first is that water molecules outnumber proteins by a ratio of about 1000:1. But proteins are giant molecules made up of thousands of atoms folded into a compact shape. When heat is applied, they unfold, stretch toward each other, and coagulate to form a tangled web. Now the water is caught in this net.

Protein begins to coagulate at 65 degrees Celsius in egg whites and 70 degrees Celsius in yolks. If the temperature continues to rise, the aggregates crowd closer together, pushing the water out. This makes the result rubbery and gives the dish an “egg” smell.

This smell comes from iron sulfide, which forms when the sulfur in the albumin protein of the egg white reacts with the iron in the yolk. This is also the reason why an egg that has been boiled too long will form a greenish-gray ring around the yolk. To avoid the smell, use fresh eggs. They are less alkaline, making the conditions less favorable for this reaction. Also, use lower temperatures when cooking and don’t cook for too long.

Now for the parting. Separate the whites from the yolks and the possibilities expand exponentially. This is because they each have different superpowers. Egg whites can swell eight times when beaten, and thus function as a larger leavening agent, helping to give volume to baked goods. They swell again because of these large protein molecules. As the proteins break down, the molecules stretch, reach out to each other and form a network that traps air and water.

Yolks, on the other hand, are great emulsifiers. Each one is essentially a bag of fat, protein and water. Fat and water wouldn’t normally stick together as cohesively, but they do because of the presence of a chemical compound called lecithin. Add a pure egg yolk when making foods like mayonnaise, ice cream and custard, and the lecithin holds everything together, making the end result smooth and silky.

Acid adds another layer of complexity. Recipes often recommend a dash of vinegar when poaching or cream of tartar when whipping egg whites. This is because in their raw form, coiled protein molecules have their positive and negative charges spread out in a carefully designed pattern. Acids contain an abundance of positively charged protons. Add one to the mix and the protons wreak havoc on the protein’s well-designed structure. Eventually, they partially unfold and coagulate some of the protein, especially on the surface. That’s why a little acid helps to partially harden the egg whites.

Combining the super powers of egg whites and yolks is possible, but difficult. In a souffle (from the French souffler, for puffed or inflated), the fluffiness of the egg whites is mixed with the flavorful components held together by the yolks. Cook the air mixture at too high a temperature, however, the pressure builds and the soufflé shrinks. Knead the dough too thinly and it will rise and fall more easily and unpredictably; make the batter too thick and it won’t rise much at all. This is a skilled baker who can make a souffle the same way every time.

Baking instructions can help, or they can feel overwhelming. They are much easier to implement when one understands the science behind them. I hope I helped with this!

(To contact Swetha Sivakumar with questions or feedback, email [email protected])

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