Everything You Ever Wanted To Know About Eggs

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Podcast Transcript

Every day around the world, over a billion eggs are consumed. 

Eggs have become a staple food product used both by itself and as an ingredient in other products. 

Humans and our ancestors have been consuming eggs of one sort or another for millions of years, and today, there is a whole system around the production and consumption of eggs that most people are totally unaware of. 

Learn more about eggs, their history, and how they are produced and consumed today on this episode of Everything Everywhere Daily.

For most of the episode, I’m going to be talking about chicken eggs because those are overwhelmingly the most popular types of eggs consumed today. 

However, chickens are far from the only animal that produces eggs. 

Edible eggs, and I’m referring here to bird eggs, not eggs from reptiles, fish, or monotreme mammals, are a result of a biological quirk where some birds will lay eggs regardless of whether they are fertilized or not. Not every bird will exhibit this behavior, and even if a bird does it, it might not do it that often in the wild. 

Every bird egg will have a shell, usually consisting of calcium carbonate. In the case of chickens, a shell is 95 to 97% calcium carbonate, the same substance that makes up seashells, coral, and limestone. 

Under the shell is a thin membrane, followed by the albumen, more commonly known as the egg white, which surrounds the vitellus, known as the yolk. 

An egg contains everything required to make a bird, including protein, fats, and a host of micronutrients. 

Human consumption of eggs is believed to date back millions of years to our earliest hominid ancesters. They would look for bird nests that had eggs and steal them. 

If you remember back to my episode on the history of the chicken, they were originally domesticated in China and/or Southeast Asia about 8000 years ago. 

It is believed that chickens were domesticated for their eggs, not their meat. This makes total sense as an egg-laying chicken can produce far more calories via egg laying over its life than it can if it is harvested once. To this extent, the origin of eggs is very similar to the origin of milk and dairy products. 

Other birds, such as ducks and quails, were quasi-domesticated early on, but it was the chicken that became the most popular source of eggs because of their size and laying habits. 

Via selective breeding, it was possible to get chickens that produced more eggs year-round. 

Eggs were consumed in Ancient Greece, Egypt, China, and in Rome. In fact, in a high-end Roman banquet, the first course was traditionally based around eggs. This necessitated the creation of recipes that used eggs as the main ingredient. 

Eggs remained a regularly consumed foodstuff for centuries, both in the old world and later in the new. During this time, egg production was mostly a small affair on small farms, although there were some monasteries and other places that focused on egg production. 

In 1878, dried egg meal was created in St. Louis, Missouri, a process that was popularized during the Second World War to ship eggs to soldiers in the field without fear of spoilage or breaking.

In 1911, a Canadian by the name of Joseph Coyle invented the egg carton, or as it is known in some commonwealth countries, an egg box. Coyle developed the egg carton to help solve a dispute between an egg producer and a hotel that complained about eggs being delivered broken.

It wasn’t until the 1950s that there was a revolution in egg production with the development of the battery cages.  Battery cages place individual chickens inside of cages, with the cages stacked on top of each other, dramatically increasing the density of chickens in an egg facility. Conveyer belts would carry away manure, bring feed to the chickens, and allow for eggs to roll down a slope to be collected. 

These battery cage systems were able to increase egg production dramatically, but there were ethical concerns about raising chickens is such small spaces. Many countries ban their use or are in the process of phasing them out. 

Today, eggs are a big business. In 2022, 87 million metric tons of eggs were produced worldwide. Assuming the average chicken egg has a weight of 50g, that would mean there are 1.7 trillion eggs laid every year. That is 212 eggs per person per year, although much of that goes into baked goods and other processed foods. 

So, with that, there is a lot of simple things about eggs that most people don’t realize. 

The first has to do with how eggs are stored and sold. For those of you listening to this all around the world, it is highly likely that all the eggs sold near you are either always refrigerated or they are never refrigerated. 

Many people don’t realize that it is done differently in other countries. 

In the United States, Canada, Australia, and Japan, eggs are almost always refrigerated. In Europe, and most other countries, eggs are never refrigerated. 

It doesn’t seem like there would be such a division. Either one, or the other would be the safe way to store and sell eggs. 

Obviously, for centuries there was no refrigeration, so people managed to store eggs just fine without it. 

The difference in egg storage has to do with salmonella, a disease that can be transmitted through chickens. 

After an outbreak of salmonella in the 1970s, the United States instituted a policy of cleaning eggs soon after they are laid. They are cleaned with hot water and soap to remove a very thin natural covering on an egg known as a cuticle. 

The cuticle normally provides a barrier for the egg which protects it from water, air, and bacteria. Without the cuticle, it is necessary to inhibit bacterial growth. 

This system of egg washing was adopted in Japan, Australia, and Canada.

In other countries, such as most of Europe, they took the exact opposite approach. They prohibited egg washing to keep the cuticle intact, thus protecting the egg. With the cuticle intact, there is no need to refrigerate the egg.

Both methods can work as seen by the large number of eggs consumed in both refrigerated and non-refridgerated countries. Each system has its pluses and minuses. Refrigerated eggs can last longer, about 50 days rather than 21. 

However, refrigerated eggs can absorb odours and flavours from other foods they are refrigerated with, and many people say that eggs at room temperature taste better. 

If you get eggs from a farmers market that aren’t refrigerated, then you don’t need to refrigerate them. 

One thing you may have noticed about eggs is that they sometimes have different colored shells. White is popular and brown is not cncomon. However, there can be speckled egg shells and even blue egg shellls, 

Shell color has nothing to do with the inside of the egg, including its taste and nutritional profile. Shell color has more to do with the breed of chicken, genetics, and diet. There are some cultural preferences for certain shell colors, but its really just a preference. 

Fun fact, because egg shells are mostly calcium carbonate, you can disolve an eggshell in vinegar. The result is a raw egg which is held together by the very thin membrane that is under the egg shell. 

The white of an egg a translucent and only turns white when it is cooked. The egg white is mostly water with about 10% protein. 

The yolk of the egg is where almost all of the nutrients are and it is where the biggest difference in eggs can be found. Chickens fed a strict grain diet tend to have light colored, more yellowish yolks. Chickens which are allowed forage naturally and have more omniverous diets, will have darker yolks. 

On rare occasions, an egg can have more than one yolk. Double yolk eggs tend to be laid more by younger and older hens, but certain breeds are more likely to have double yolks as well. 

The odds of getting a double-yolk egg have been reported to be about 1 in 1000, and the odds of a triple-yolk are estimated to be about 1 in 25,000,000. 

The Guinness Book of World Records has determined the most yolks in a single egg to be 9. The record egg was found by Diane Hainsworth of Hainsworth Poultry Farms, located in Mount Morris, New York, in July 1971. 

When you are buying eggs, at least in the United States, there are several things to look for on the carton. 

The first thing that will be listed is the grade of the egg. Eggs can have one of three grades: AA, A, and B. The grade of an egg is determined by the shell and the yolk. 

A AA-grade egg will have an unblemished shell and a firm round yolk with no spots of blood inside. The yolk can be analyzed via a device known as an egg candler, which is really just a bright light that can shine through the egg, giving you an outline of what’s inside.

A single-A-grade egg is not that much different than an AA egg. The yolk is perhaps a bit less defined, and there might be minor blemishes on the shell. The biggest difference between AA and A is aesthetics. 

A B-grade egg, however, is very different. There might be a hairline fracture on the shell, meat or blood spots inside the egg, or other defects. Grade B eggs are almost never sold directly to consumers. They are perfectly edible, but they are usually sold to commercial operators who would use them in bulk. 

If there is anything worse than a B grade, it will usually be destroyed. 

Another thing you will find on most egg cartons is a size. Eggs have six size classifications: Peewee, Small, Medium, Large, Extra Large, and Jumbo. 

The size classifications are actually made via weighing the egg, not by measuring the size or volume. However, the odds are that an egg will have a larger volume the more it weighs. 

The final thing that you will find on a carton of eggs is something that isn’t nearly as defined or regulated: the living conditions of the chicken. 

If there is nothing whatsoever on the package, then the odds are that the chickens were raised in a very small cage of only about 67 square inches. The chickens are only fed a diet of corn or soy.  This is how the vast majority of commercial eggs were produced. 

The next term, which is rather deceptive, is the term “cage-free.”  Cage-free sounds like the chicken is able to just walk around a farm field all day. In reality, a cage-free chicken will never be outside and see sunlight. They have a space of approximately 1.2 square feet allotted to them, only slightly larger than caged chickens. They might not be in a cage because they can walk around a crowded area. 

The next type is free-range chicken eggs. Free range again evokes certain images. In reality, it is probably not that different from the environment cage-free birds are raised in, except they get a bit more space on average and have to have some access to the outdoors. 

The final and most expensive type of egg is pasture-raised eggs. Pasture-raised eggs are pretty much what you’d expect. Chickens have vastly more space, often over 100 sq/ft per bird, are almost always outside, and have a more varied diet because they can peck and scratch at the ground. 

None of these four terms to describe living environments are legally defined, nor are they strictly enforceable. 

Eggs are enormously popular and widely consumed. What we do today is simply the modern version of what our hominid ancestors did who would often steal eggs out of a bird nest when they could find them.