The following egg experiments aren’t cheep tricks! They provide an excellent opportunity to spark curiosity about the natural world in children (and curious grownups) while also explaining some of the principles of physics and chemistry.
There are many different STEM (Science, Technology, Engineering and Math) projects that can be done using eggs. Here we present a few more of our favorites that use materials you likely already have around the house.
So grab an egg carton, and let’s see if these science experiments are all they’re cracked up to be!
The Incredible Shrinking Egg
For this experiment, you’ll need the following:
- a hard-boiled egg, cooled and peeled
- a glass bottle with a mouth that is about 1 1⁄2 to 2 inches wide (slightly narrower than the egg)
- a match
- a small piece of paper
- a responsible adult
Use some water or vegetable oil to make the mouth and neck of the bottle a bit more slippery. Then, have an adult use the match to light the strip of paper and drop it into the glass bottle.
Quickly place one end of the egg on the mouth of the bottle and wait. The fire will go out soon, and the egg should drop into the bottle!
How does this work? The fire causes the air in the bottle to heat up and expand, but some of this air escapes from the bottle, past the egg. When the fire goes out, the air left in the bottle cools off and contracts.
This creates an area of low air pressure inside the bottle. Air from outside tries to enter and pushes the egg into the bottle.
Put an egg in a cup of water, and watch it sink to the bottom. This happens because the density of the egg is higher than the density of the water.
However, if you add enough salt to the water, the egg will float back up to the surface. Adding salt increases the density of the solution. The salt increases the mass without changing the volume very much.
When enough salt is added to the water, the saltwater solution’s density becomes higher than the egg’s. This will cause the egg to float.
Next, let’s examine the science behind two popular uses of eggs in cooking and baking. First, how do eggs change when they’re cooked?
Eggs contain large amounts of proteins, especially in the egg whites, which are about 90 percent water and 10 percent protein. These proteins are folded-up molecules made of chains of smaller building blocks, called amino acids. Amino acids are kept folded by weak bonds between different parts of the protein.
When an egg is fried, the heat breaks the weak bonds. The protein chains unfold in a process known as denaturing.
These unwound proteins now can form new bonds with each other and create a web of connected proteins that prevents water molecules from flowing freely. This results in egg whites becoming solid.
Unlike the white, the yolk is about 50 percent water, 30 percent fat and 20 percent protein. The fat in the yolk slows the breaking of protein bonds and formation of new webs of proteins. As a result, the yolk cooks slower than the egg white.
Next up in our egg experiments, let’s examine a way to separate the yolk and egg whites. Then we’ll learn how to whip egg whites to create fluffy foam.
To separate the yolk from the egg whites, we can use air pressure to our advantage. By taking a plastic water bottle and squeezing it, we reduce the amount of air in the bottle. Then, if we place the mouth of the bottle on the yolk (without breaking it) and stop squeezing the bottle, the air pressure in the bottle decreases.
Air attempts to rush in, drawing the yolk up in the process.
Now, we can take the separated egg white and whip it into fluffy foam. Whipping the egg whites unfolds the protein chains, just like heat. It introduces air bubbles into the mix as well.
The unfolded proteins form new bonds with each other, creating a web that holds air bubbles inside the foam. This new arrangement of proteins causes the egg white foam to become more solid. The air bubbles trapped inside are what cause treats that contain whipped egg whites to be light and fluffy.
If you really want to make this experiment yummy instead of plain old fluffy foam, you can make a meringue! Additional ingredients include sugar and cream of tartar. Sugar makes it taste good (of course) while the cream of tartar (an acid) stabilizes the egg whites and keeps the proteins in them from sticking together.
This is what gets you that nice, fluffy, airy mouth feel.
This is one of our more impressive egg experiments. You don’t need to wait until April Fools’ Day for a good practical joke. You have to keep your family and friends on their toes throughout the year! A great way to do this is to make your chicken eggs have red-colored yolks.
The same principle that makes egg yolks yellow can also make egg yolks red. Big picture: Yolk color in laying hens is primarily determined by the content and profile of pigmented carotenoids (yellow, orange or red pigments that dissolve in fats present in plants) in their feed.
Yolk color doesn’t correlate with any specific nutritional benefits. But in many parts of the world, including the United States, consumers usually prefer to eat eggs that have darker colored yolks.
But dark yellow isn’t the only color they can be!
To give your hens red-orange-colored yolked eggs, feed them red chili peppers at a concentration between 1⁄2 to 2 percent for about two weeks.
Note: Birds don’t sense “hot” or “spicy.” This is why you can add cayenne pepper to your birdseed to discourage squirrels from eating the seeds. Now, if there was only a way to make the yolk purple with pink polka dots!
Thank you for checking out this issue’s batch of egg experiments and science. We hope you were thoroughly hen-tertained! Check out our original batch on experiments here.
Sidebar: Did You Know?
- Eggs are about 105 degrees Fahrenheit when laid. According to the Iowa Egg Council, as they cool, the liquid inside contracts. An air cell forms between these two layers at the large end.
- Eggshells aren’t completely solid and contain as many as 7,000 to 17,000 tiny holes—1⁄1000 of an inch across—which allow for the input and output of oxygen, carbon dioxide and moisture.
- The white and yolk are close in terms of protein. But the yolk has much of the egg’s omega-3 fatty acids, vitamins B6 and B12, folic acid and all of the A, D, E and K vitamins.
- Chickens don’t produce one egg at a time. Instead, hens normally have several eggs in various stages of development.
This article was written by Alec Michael a Ph.D. student in epidemiology at UC Davis and Maurice Pitesky, D.V.M. and faculty at the UC Davis School of Veterinary Medicine. It originally appeared in the September/October 2021 issue of Chickens magazine.