Why do you have to add eggs one at a time while baking?

Baking is a task filled with rules that you must follow to achieve success. You can’t just wing it like you may do when cooking. There is no pinch of this or handful of that in baking; there is only measuring carefully. Many people don’t like to bake because of all the rules, while others prefer baking over cooking because of its rigidity. Whether you’re a fan of baking or not, if you’re going to follow a recipe for baked goods, it may help to know why you’re following the rules that you are.

One of the most common baking rules that people follow, but have no idea why, is adding eggs one at a time. If you’ve ever wondered why you can’t just crack all of the eggs and put them in at once, read on to put some purpose behind your actions.

egg being cracked into a bowl

When it matters

Adding eggs one at a time is a step most often used in the creaming method of cake making. The creaming process requires that you start with butter, and mix — or “cream” — the sugar into the butter. The next step is to add the eggs one at a time before adding the other ingredients. The process of creaming the sugar into the butter creates air pockets in the butter, which is one of the main things that causes the cake to rise in the oven. The addition of the eggs, one at a time, best incorporates the eggs into the butter. It is essential when creaming to have all of the egg incorporated into the butter. But what does “incorporate” mean in this instance?

man cracking eggs


Emulsification is the “process of dispersing two or more immiscible liquids together to form a semi-stable mixture,” according to ScienceDirect. In cooking or baking applications, the two liquids consist of an aqueous (water) phase and an organic (oil) phase that is stabilized by the addition of a food-grade emulsifier (surfactant). So, in baking terms, the butter is made of water and fat, and the egg acts as an emulsifier to create the creamed finished product. The reason eggs help bring the water and oil in the butter together is because egg yolks contain lecithin, a natural emulsifier.

All of this boils down to chemistry. Every time you bake, you are conducting a chemistry experiment — it may be delicious, but it’s still an experiment. This is why measuring is so important when baking. This is also why emulsification is necessary. Everyone knows fats and liquids are unmixable by nature. Butter is at least 80% fat, and egg whites contain a ton of water. The lecithin in the egg yolk acts as an emulsifier and allows the butter and egg whites to come together nicely.

What’s the point?

So, what does all this science talk have to do with baking delicious, sweet treats? The first thing adding eggs one at a time does is save you time. Adding eggs one at a time takes less time for each egg to incorporate into the creamed butter and sugar. While saving time is a plus, this is not the main reason experienced bakers add their eggs one at a time. The main reason is about texture. The texture of the finished product, whether it be cookies or cakes, is much better when you take the time to add each egg one a time and allow each egg to incorporate fully before adding the next. If you add the eggs all at once, your cookie batter will be too thin and spread too much, thus creating an uneven and not as chewy cookie. When it comes to cakes, adding all of the eggs at once will create a denser and slightly rubbery cake. If you’re going to take the time to make desserts from scratch, you want them to turn out as texturally desirable as possible, which is why adding the eggs one at a time matters.

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