When you think about it, baking is a science. That’s why using the correct ingredients and mixing them the right way is key to baking with precision. Eggs are an impressive piece of scientific cookery, as they contain many different proteins and amino acids. Eggs are literally in everything we bake. But, what do eggs do in a cake? Eggs are one of the most important, if not the most important ingredients in cake.
When you’re talking about what is the purpose of eggs in a cake, their protein power allows them to do quite a lot of heavy lifting. Eggs influence things like structure, moisture, and rise in a cake.
Keep reading below for everything you need to know on how eggs can help you bake the perfect cake!
What is An Egg?
For all those living under a rock and have no idea what an egg is, it is a hard shelled vessel grown by an animal to carry a potential embryo. The most commonly used eggs in baking come from hens. We use eggs in baking, we eat them for breakfast, we fry them, poach them, boil them, and scramble them. Eggs are versatile little things and extremely delicious too.
Because of the way farming practices have been standardized, eggs have a remarkably similar composition no matter where they come from.
An egg is made up of about 65% albumen – the egg white – and about 35% yolk. A whole egg contains all essential vitamins and many important minerals.
The high-quality protein in an egg contains all the amino acids a person needs in their diet. Most of an egg’s nutrition is in the yolk, and the white contains mostly water and 10% protein.
What is the Purpose of Eggs in Baking?
Binding and Structure
The number one thing eggs do in a cake is bind all the dry ingredients together during the baking process. As the egg cooks in the oven, the amino acid chains that make up the protein in the egg start to denature, going from long strings to tighter, more solid clumps.
When this denaturation happens with other ingredients, the eggs pull those ingredients together and bind them into the protein.
This is how we get our delicious cakes to hold together.
Leavening
As the consistency of the egg holds air particularly well, eggs are a great natural leavening agent, unlike baking powder or baking soda which are artificially made.
Egg whites, in particular, hold air even better, and can be whipped to the point that they stand in for baking powder as a raising agent in some cakes. If you’ve made a meringue based dessert before, like pavlova, then you’ll know how great egg white are at trapping air.
Whipping egg whites will have the same effect as partially cooking them – the proteins start to denature and the egg white starts to gel, trapping the air inside the egg. If you use this method to make your cakes lighter and fluffier, be sure not to over-whip the egg whites, and carefully fold the whipped egg white into the batter. To get air into the egg whites you need to mix them vigorously, so using a hand or stand mixer will make the job a whole lot easier. Trust me, your arms will thank you later!
Emulsification
Emulsifiers are agents which allow two ingredients that don’t usually mix – like oil and water – to combine properly. Egg yolks have many different proteins and amino acids that do the same thing. Some of these are hydrophilic and attracted to water; others are hydrophobic and repel water.
When you mix these under heat, the egg acts as an emulsifier and sets both oil and water together.
An important amino acid found in eggs is lecithin, which has one end that is hydrophobic and one which is hydrophilic. Lecithin binds fat molecules to water molecules so they can’t separate.
Watch these egg yolks emulsify into a delicious hollandaise sauce!
Moisture
It’s worth remembering that eggs themselves are roughly 75% water, so by adding eggs, you’re adding valuable moisture to your cake from the start.
However, eggs also help your cake retain moisture during the baking process, so they’re less likely to dry out in the oven (or too quickly afterwards).
This happens mostly when you use egg yolks, because that’s where those hydrophilic and hydrophobic enzymes are found.
Moisture blends into the cake by clinging to both fats and water, rather than being evaporated.
Flavor
Eggs not only add flavor to baked goods by binding ingredients together, but the fat in the yolk also enhances the taste of other ingredients. The yolk is rich in fat, and that richness helps to add flavor and texture to cakes and other baked goods
Nutrition
Eggs are a highly nutritious food that is rich in many different nutrients and vitamins. They contain high levels of protein and all nine essential amino acids, which is an essential building block for our bodies and can help to support muscle growth and repair. In addition, eggs are also a good source of healthy monosaturated and polyunsaturated fats.
So, does that make cake healthy? Debatable.
Fat
Fat enhances flavor, and with eggs, that happens in more ways than one. Remember that egg whites contain no fat, so this is where you shouldn’t skimp on the yolks.
One significant benefit that eggs offer works with their binding and moisture-increasing properties – the more water you can retain in the cake batter, the more sugar the cake can hold. The fat in eggs increases the amount of water you can retain in the batter. It does this by giving the water and amino acids something to bind to.
Color
Eggs can help contribute to the color of your cake in a few ways. Because they brown reasonably quickly, you can get a lovely brown cake crumb even if you’re cooking at a low heat or if your cake is only in the oven for a short time.
Eggs also impact the inside of your cake – light sponges develop a rich, yellow color from the egg yolk. This color has long been considered a sign of quality!
While it isn’t used often on cakes, egg washes and glazes help add a tasty-looking hue to pies and pastries.
How Does The Amount Of Egg Affect A Cake?
What Happens When You Bake A Cake Without Egg?
If you’re using an adequate egg substitute, you might find your cake doesn’t taste quite the same as if you’d used eggs, but it won’t be a disaster.
Forgetting to add any eggs at all will result in a less-than-ideal cake. Your batter will be thin, it won’t be properly incorporated because it lacks the emulsifier, and it will collapse when it’s baking. Since eggs are a powerful binding agent in a cake, you’ll find that your cake will probably fall apart when you take it out of the oven.
What Happens If You Don’t Add Enough Eggs to a Cake Recipe?
So, the recipe calls for three eggs, and you’ve only got two. What happens if you just go with that?
Well, it won’t be as terrible as if you’d left them out completely! However, the cake will still lack structure, and you risk it collapsing as it bakes.
Depending on how much butter and sugar the recipe contains, the cake may come out greasy because those ingredients couldn’t be mixed into the batter properly.
What Does Adding More Eggs Do To A Cake?
Have you ever heard the phrase, “Don’t over-egg the pudding”?
It means not spoiling something by trying too hard to improve it – but the root of the saying is literal. Adding too much egg to your pudding can spoil it!
Now, for certain cake recipes, you might improve it by adding more egg than the recipe dictates. For instance, adding an extra egg to a dry recipe will help it retain more moisture.
However, adding too many eggs will result in the cake becoming heavy and starchy, less likely to rise properly, and with a final texture that’s coarse rather than fluffy.
The Bottom Line
Eggs can truly make or break your cake! In addition to all these great functional properties above, eggs are a versatile ingredient that can be used in countless different ways in baking. Whether it’s whipping up some fluffy meringue or torte, or adding richness and moisture to cakes and brownies, eggs are one of the most important ingredients in your pantry. So next time you’re making a cake or batch of cookies, don’t forget the humble egg!
Regardless of whether you are a novice baker or a professional, knowing the purpose of eggs in baking is important. Too much egg in your cake can make it spongy or rubbery, but too little and your cake won’t hold together at all.
