Everything You Need to Know About Chicken Eggs

Quick Take

• The reason most people choose white over brown has nothing to do with what's inside. See why color doesn't matter →
• A simple kitchen trick can tell you whether your eggs are safe to eat, though most people have never tried it. Try the freshness test →
• Whether your eggs need refrigeration depends on something that happens to them long before they reach your kitchen. Find out about egg washing →
• The color of an egg yolk is not random. It is a direct signal about the life the hen was living. Discover what yolk color signals →

The incredible edible chicken egg is one of the world’s most versatile and nutrient-dense dietary staples. Packed with high-quality protein, essential vitamins (like B12 and D), and crucial brain nutrients like choline, eggs are an affordable, healthful part of the human diet. Worldwide, people consume over one trillion eggs annually, supplied by commercial farms and backyard flocks. Continue reading to discover everything you need to know about chicken eggs.

What is the Difference Between Brown Chicken Eggs and White Chicken Eggs?

Everyone has their preference when it comes to brown or white chicken eggs. The French believe that darker eggs are more nutritious and have better flavor. But the truth is, there is typically no nutritional difference between brown and white eggs. Worldwide, over 90% of commercially produced chicken eggs are white.

The color of an egg’s shell depends on the breed of chicken that lays it. Interestingly, brown eggs come from hens with brown feathers, while hens with white feathers produce white eggs.

Thanks to selective breeding and genetics, chickens lay a vibrant array of egg colors, including shades of blue, green, pink, and cream.  Eggshell color ultimately comes down to genetics. Blue eggs, for example, are caused by a pigment called oocyanin, which is deposited early in the shell-forming process. 

Why Are Some Egg Yolks Orange?

It is normal for an egg yolk to be yellow or deep orange. The difference in coloring is based on the hen’s diet. Free-range chickens that eat vegetation and insects produce orange yolks, while hens that receive grain feed usually lay eggs with yellow yolks.

Although some people believe that hens only lay eggs if a rooster is present, this is untrue. Most commercial egg farms do not keep roosters, since hens lay eggs without fertilization, and the goal for eggs sold for consumption is for them to be unfertilized. However, eggs bought from a farm or farmer’s market might occasionally be fertilized.

Why Are Some Eggs Bigger Than Others?

When purchasing chicken eggs at the store, you usually have the option of small, medium, large, x-large, and jumbo. While a hen’s eggs will naturally increase in size as she ages, each breed has a baseline average egg size and weight that it will consistently produce.

Bantam breeds (miniature chickens like Silkies) naturally lay small, golf-ball-sized eggs. Medium to large layers generally produce medium-sized eggs, while larger birds like Leghorns and Rhode Island Reds lay large to extra-large eggs.

How to Tell if an Egg is Fresh

Eggs can last for several weeks (typically 3–5 weeks) when refrigerated, so the eggs in the store may not be as fresh as you think. Fortunately, there are ways to tell if a chicken egg is fresh.

The easiest way to tell if an egg is fresh is by submerging it in water. If the egg sinks to the bottom, it is fresh. However, if the egg floats to the surface, it is rotten and should not be consumed.

Should You Refrigerate Your Eggs?

Unwashed farm-fresh eggs do not need to be refrigerated. Because these eggs have not been washed, they still retain their natural protective coating called the cuticle or bloom. This invisible barrier seals the porous eggshell and effectively blocks bacteria from entering the egg. Unwashed eggs can stay fresh at room temperature for about two to three weeks. If refrigerated immediately, they can last up to three months.

The reason eggs in the US require refrigeration is that commercial egg producers are required to wash their eggs with warm water and a sanitizing agent. While this removes dirt and feces, it also strips away the egg’s natural protective coating (the cuticle), making the shell more porous and susceptible to bacteria.