Understanding Eggs: Behind the Ingredients

There is a lot of freedom in knowing how key ingredients work the way they do. Leave the guesswork behind in the first of this Behind the Ingredients series where we dive into learning about the humble egg.

THE HUMBLE, YET MIGHTY EGG

Almost all of us have eaten eggs at some point in our lives and many of us reach for the egg carton first thing in the morning. Apart from making bacon and eggs, why is it that eggs are called for in so many recipes? What is it about eggs that keep us hungry for more?

Well, for one, eggs are a complete protein checking off all the essential amino acids. Eggs also have a number of B vitamins, vitamin E, iron, minerals, and other nutrients you can easily look up online. They’re nutritious, they keep us full, and they’re relatively inexpensive.

We don’t usually think about these things when we fry, scramble, or poach these edible gems. They’re humble in that they’re depended on, yet overlooked. When’s the last time you’ve been grateful for eggs? During rationing in WWII, eggs were a precious commodity and unless folks kept their own chickens, dried egg powder took the forefront. Gross. Indeed, eggs are humble, but they’re also mighty.

RELATED: Sauerkraut and Bacon Quiche

UNDERSTANDING EGGS: THE VIDEO

Here’s the first video in the Behind the Ingredients series. If you like what you see, I hope you’ll consider subscribing to my YouTube channel!

This post on may contain affiliate links, meaning that if you choose to purchase something after clicking on one of the links in this post, I may earn a small commission at no additional cost to you.

UNDERSTANDING EGGS: THE FOUR MAIN FUNCTIONS

When a recipe calls for eggs, do you ever ask what purpose they serve the recipe? Sometimes eggs can be substituted with ingredients like ground flax mixed with water, apple sauce, buttermilk and silken tofu, to name a few. But these substitutes won’t work for everything and substitutes are not something I will be focusing on today.

When it comes to baking and cooking, eggs are usually needed to…

• Leaven.
• Emulsify.
• Thicken.
• Create structure.

Let’s get into each one, shall we?

LEAVENING

I can’t even tell you how many times I’ve beaten egg whites to soft or stiff peaks. There are the times I whisk yolks with sugar until they’re the palest yellow, like when I’m making a genoise sponge cake. I’m always so careful every time I fold that precious egg white fluff into a batter. I do this when I make chiffon cake, angel food cake, ladyfingers, and soufflés. We go to all that trouble for one reason only: volume.

I have more to say about volume, but for now, I’ll explain what happens when these dishes hit the oven. In case you didn’t know, trapped within all that hard-earned egg foam is air. The heat causes these air bubbles to expand, leavening the cake in the process without using chemical leaveners like baking powder or baking soda. So the next time you want to lighten up a recipe, fold in some egg whites!

EMULSIFYING

In case this word isn’t familiar, an emulsifier is an ingredient that stabilizes a mixture that wants to separate. One example that comes to mind is a salad dressing, which usually combines oil and vinegar. Without an emulsifier, the oil and vinegar will separate, but with a simple addition of mustard (an emulsifier), the oil and vinegar molecules are bound together. Does that make sense?

When it comes to eggs, the yolk holds all the emulsifying power. Most people know all the fat is in the yolk and that it contains cholesterol, but did you know that it’s also comprised of lecithin? Lecithin is an emulsifying agent that you will often spot on food labels, although when it comes to consumer packaged goods, the lecithin usually comes from soy.

When you’re making choux pastry to make eclairs, cream puffs or elegant appetizers, you need to add eggs bit by bit so the batter doesn’t break. That’s emulsification. Making mayonnaise? You start with an egg and a bit of acid, like lemon juice, then slowly dribble in the oil, whisking like mad. The egg will turn that acid and oil into that classic sauce we know and love on our BLTs.

CREATING STRUCTURE

Eggs do, oh, so many things. They make cakes and bread richer, keeping them moist and giving them a nice crumb. In my sweet shortcrust pastry dough (pâte sucrée), eggs are included to add to the richness of the dough and to help firm it up. They also contribute to the structure of baked goods. Do you know how eggs are a protein? Well, when the proteins in the egg heat up, they begin to set.

As the batter slowly heats in the oven, the proteins coagulate and add to the overall structure of a recipe. If you look at a quiche, you can see that coagulation at work. While there isn’t any added flour for the egg to work in tandem with, you can see what happens on a more condensed scale. After enough time at a steady temperature, the egg completely sets.

THICKENING

In pastry, eggs are beloved for their thickening powers. This ability comes from the very same proteins that add structure to a recipe. As the eggs are slowly heated, they coagulate and work to thicken sauces. Custards, like vanilla pudding, are a prime example, as are curds. Flans and créme brûlées wouldn’t be the desserts they are without eggs because they wouldn’t set and their flavour would be impacted. There’s just one thing that you need to do when you mix eggs into hot liquids…

TEMPERING

When it comes to eggs, tempering is a technique that’s employed to ensure eggs don’t get shocked and curdle. It’s paramount that eggs don’t curdle, because when the proteins scramble, they lose their ability to thicken. To temper eggs, the hot liquid needs to be whisked into the eggs before the eggs can be added to the pot to thicken.

Let’s say we’re making a crème anglaise so we can make spiced oatmeal cookie ice cream sandwiches. The cream or milk comes to a near boil, so we remove a ladleful and whisk it into the eggs. We follow that ladleful with another, then another, until half the cream is in the eggs. From there, the egg mixture goes into the pot to finish thickening.

AT WHAT TEMPERATURE TO EGGS BEGIN TO SET?

First off, eggs curdle when they hit 180ºF/82ºC. Water boils at 212ºF/100º, so it doesn’t take a whole lot of heat. That’s why low and slow is best. No shocking the eggs, please! Anyhow, egg whites begin to set around 144-149ºF/62-65ºC and yolks around 149-158ºF/65-70ºC. Adding additional ingredients like sugar, starch and water raise the temperature that eggs begin to coagulate at, so this is something worth bearing in mind.

DON’T FORGET ABOUT THE EGG WASH!

There have probably been a few times where you have brushed egg onto something before popping it into the oven. Whole eggs are typically beaten to achieve two things: colour and lustre. It’s the yolk that imparts the rich colour and the white that gives the sheen. I’ll let you in on a baker’s hack though: to get a lump-free egg wash, add a pinch of salt!

THE YOLKS INHIBIT THE FORMATION OF SUGAR CRYSTALS

Fun fact! It’s the lecithin in the yolk that does this. What does this new egg factoid mean for you? If you’re a fan of buttercream or making candies, understanding eggs in this way will help. Adding an egg yolk to frostings and some confectionary will make them less grainy.

UNDERSTANDING EGGS AND RESPECTING THE DANGER ZONE

Recipes like mayonnaise, tartare, and hollandaise sauce usually call for the addition of a raw egg. This leaves some folks worrying about the potential for salmonella poisoning. According to the American Egg Board, approximately 1 in 20,000 eggs are contaminated with salmonella. That’s over 1,600 cartons worth of eggs. That’s a lot! However, there are precautions to take with eggs to ensure there’s no cause for harm.

In the culinary world, the temperature range where bacteria grow the most rapidly is referred to as ‘the danger zone’. The range is between 40°F – 140°F or 5°C – 60°C. When meat and eggs, are left to sit at room temperature after being pulled from the fridge or removed from the heat, they enter the danger zone.

This is why it’s important to rapidly cool concoctions like custard by either popping the cooking pot into an ice water bath or transferring it to the fridge straight away.

Oh, and if you ever come across a cracked egg, don’t be tempted to use it. Toss it in the compost and forget about it. Better safe than sorry!

ROOM TEMPERATURE EGGS

When you’re using eggs to leaven or add structure, recipes often call for eggs at room temperature. That’s because warm eggs gain more volume than cold eggs do. Guess what? There’s a hack for this that doesn’t involve leaving eggs out all morning or afternoon.

One way is to set the eggs in a container of hot water to take away the chill. The problem with this method is that warmth increases the chances of the yolk breaking, which is problematic if you need to separate the eggs.

If you’re separating the eggs, the other way to bring them to room temperature is to separate your eggs when they’re cold and then set the bowl that’s holding them in a shallow water bath.

HOW SHOULD I STORE MY EGGS?

From the day they are packaged, eggs have a shelf-life of around five weeks. A carton of eggs seldom lasts longer than two weeks in my kitchen, but if it takes you longer to get through them, there are a couple of things worth bearing in mind.

1. Storing eggs towards the back of the fridge keeps them at a steady temperature of 39ºF/4ºC. When eggs are stored towards the front, the fluctuations in temperature from the door being constantly opened and shut impacts their shelf-life.
2. If you accidentally leave your eggs out overnight, they're still good. However, every time this happens, it shaves a week off of their overall shelf-life.
3. Keep the eggs in the carton. The cartons do more than protect eggs from breakage: they also keep eggs safe from bad fridge odours and moisture loss.

DID YOU KNOW EGGS HAVE A COATING?

When eggs are first laid, they have a natural coating that seals them from moisture loss and protects them from bacteria and other contaminants. As soon as eggs are washed, this coating is removed as are the benefits that come with it.

It probably comes as no surprise that all commercial eggs are washed. To protect the eggs, they receive a thin coating of mineral oil. Therefore, if you feel the need to wash your eggs, you should plan on using them right away!

UNDERSTANDING EGGS: FRESH VS OLD

One of my dreams is to have egg-laying hens so I can always have access to fresh, free-range eggs. Fresh eggs, if you didn’t know, are cherished for poaching because the whites are thicker. As eggs age, the whites grow thinner, making the yolk more susceptible to breaking. If you’re hard-boiling eggs, on the other hand, you will want to reach for the older eggs because they will be easier to peel.

Another difference is that older eggs become more alkaline and the texture changes a bit. Let’s take the chalazae to start. Do you know how eggs have a twisty, opaque strand thing? That’s the chalazae. It’s much more prominent in fresh eggs than in older eggs because its purpose is to anchor the yolk to the shell. It has no impact on your recipes, but if you’re making custard and want to make sure it’s extra velvety, you can always strain it.

Another key difference is in foaming performance. Older eggs are quick to gain volume when you whip them up, but fresh eggs take longer to form peaks. With that being said, the finished product made with fresh eggs will achieve a better volume than it will with older eggs. Fresh egg foam, as it turns out, is more stable.

THE COPPER BOWL EFFECT

Speaking of egg foam, did you know that beating your whites in a copper bowl will give you the best possible results? A copper bowl makes it almost impossible to overbeat your whites, and it will make for a more stable foam when baking. This works because of a protein in the egg called conalbumin, which reacts with copper. Working with a copper bowl will also help whites retain their moisture, so they will weep less than eggs that are beaten in a non-copper vessel. Neat, huh? The downside is that copper bowls are expensive, but they sure are pretty!

WHAT IF I DON’T HAVE A COPPER BOWL FOR MY EGG WHITES?

Don’t worry, I don’t either. Maybe one day I’ll have one of those beauties to beat my egg whites in, but for now, I use an ordinary stainless steel bowl. When you’re beating egg whites, it is imperative that you keep them free from fat particles. A trace of yolk will ruin your whites and you’ll have a hard time getting the volume that you need for your recipe.

As a best practice, always rinse your mixing bowl with cold water and then dry it off with a clean cloth. Avoid using plastic bowls, if you can. Plastic has a tendency to cling onto fat residue. If you wash a lot of plastic containers by hand, you’ll know what I mean. By the way, if you don’t have a stainless steel bowl, the next best bet is ceramic.

CAN I FREEZE EGGS?

If you have an excess of eggs and don’t want to pickle them, you can always freeze them, but make sure to crack them open first! The water in the eggs will expand when it freezes and the last thing you want in your freezer is an egg-splosion, right? I’m sorry, but there had to be at least one bad egg pun in here!

Frozen eggs are used a lot in bakeries because they’re quick and easy to use. Why waste labour on cracking and separating eggs when you can defrost a couple of cartons of egg whites from the freezer? Egg whites freeze beautifully and you’ll hardly notice a difference in performance. The same holds true for whole eggs mixed together

Egg yolks, on the other hand, are the exception. When yolks are frozen as-is, they lose their smoothness. That’s why sugar or salt is mixed into the yolks before they are frozen to preserve their smoothness. If this is something you want to try at home, the rule of thumb is to use 1/8 tsp of salt or 1.5 tsp of sugar for every 4 egg yolks.

THANKS FOR DROPPING BY THE KITCHEN!

I really hope you enjoyed today’s theory post on eggs! If there’s another ingredient you would like to learn the theory behind, drop me a line in the comments below. Or, if you want to put yourself through baking theory class, Joseph Amendola and Nicole Rees wrote the Understanding Baking textbook I learned from when I was a student learning about the baking and pastry arts. If you’re already well-versed in egg theory, is there anything I missed? Thank you for reading!

SHOP THIS POST

Mauviel Copper Egg White Bowl

Understanding Baking by Joseph Amendola and Nicole Rees

OTHER POSTS YOU MIGHT BE INTERESTED IN

How to make pâte à choux (choux paste)

Sweet shortcrust pastry dough for tarts and pies

Vanilla pudding (pastry cream)

PIN IT FOR LATER

Love and gratitude,