Egg Facts – Top 10 FAQs About Eggs
Here are 10 egg facts based on questions I am frequently asked. I love getting questions like these and digging a little deeper to better understand more about our food. I gathered this information from various sources including Canadian Food Inspection Agency, Canadian Eggs, Manitoba Egg Farmers, Dietitians of Canada, etc. I also had an opportunity to tour a Manitoba egg farm to learn more about our eggs.
Here are my Top 10 FAQs about Eggs. Share this post with your curious friends!
Read more: Easy Peel Boiled Eggs, Leftover Egg Ideas, Dilly Egg Salad Recipe, Which Eggs to Buy
Top 10 Egg Facts You Need to Know
1. Are Eggs Good For You?
Yes! Eggs are an excellent, inexpensive source of high quality protein and nutrients such as Vitamin B12, riboflavin, Vitamin D(one of very few foods that provide Vitamin D), folacin and choline. Eggs also have some iron, although it may not be absorbed as readily by the body than other sources of iron (eating eggs with foods high in Vitamin C like citrus fruits, peaches, papayas, sweet red peppers, berries, broccoli, and peas can help absorption of iron). The nutrient content chart is from the Manitoba Egg Farmers which also provides further information on the benefits of key nutrients.
The nutrients of eggs are not equally distributed between the egg whites and egg yolks. While egg whites offer the highest concentration of protein and some B vitamins, most of the nutrients and minerals are found in highest concentration in the egg yolks. Your best bet is to eat the whole egg!
And yes, eggs are a healthy choice for everyone, unless your Doctor has specifically said differently. The American Heart Association  recommends one egg (or two egg whites) per day for people who eat them, as part of a healthy diet.
2. Are brown eggs or white eggs more nutritious?
The shell colour, size of eggs, or how hens are raised does not change the nutrient content of eggs. So a brown egg is no more nutritious than a white egg. What they eat, however, does make a difference.
What hens eat, impacts the nutrient content of eggs. For example Omega 3 eggs are from hens fed a diet high in flax seed. Eggs labelled – “Vitamin Enhanced” are from hens fed specific diets rich in particular vitamins. Farmers work with poultry nutritionists to ensure the hens’ needs are met. Here’s Manitoba Agriculture’s recommended feeding regime for egg farmers wanting to increase the Omega 3 content of their hens’ eggs.
The colour of the yolk is also impacted by a hen’s diet.  A diet high in corn, alfalfa, or other greens high in carotenoids will produce more golden yolks. To control yolk color commercial producers may add supplemental carotenoids such as canthaxananthin or marigold to the feed to produce deeper colored yolks. A darker yolk does not automatically mean more a more nutritious yolk.
My sister has laying hens that produce just enough eggs for her family. Her hens are free to roam the entire farm yard eating whatever is available (grass, weeds, flowers, worms, grubs or insects). So the nutrient content and the colour of the yolks in her hen’s eggs is more variable and changes throughout the seasons.
Did you know…
- Free Run means hens are kept loose in a barn without access to outdoors/
- Free Range means hens are kept loose in a barn with access to outdoors (weather dependent). Read more about Free-Range and Free Run Chickens.
3. How long do eggs last – what’s the shelf life?
- Raw eggs in shell: 30 days or 3-4 weeks past best before date
- Cooked eggs in shell: 7 days
- Peeled cooked eggs out of shell (no other ingredients): 7 days
- Scrambled, deviled, frittata, quiche, omlette, etc: 3-4 days in fridge
It takes 4-7 days for eggs to hit the store shelf from when they’re laid.  According to Egg Farmers of Canada the Best Before date on the package is 28 to 35 days from the date of packing. Like other Best Before Dates, this date indicates quality, not safety, for eggs the Best Before Date indicates the length of time the eggs will maintain their Grade A quality.
An egg can still be used after the Best Before date, but should be cooked thoroughly (use in baking). There isn’t a specific number of days, it varies – but if stored well – eggs can last 3-5 weeks past the BBD.
What happens to eggs as they age?
- the yolks flatten and whites get thinner
- they will provide less structure in baking and meringues
- the air pocket will expand – making older eggs easier to peel
- they may develop a slightly sulfurous flavour
When to toss old eggs:
When your eggs are past their Best Before Date, always crack them into a separate bowl. If they show any of the following signs – don’t use!
- Shell is cracked or slimy
- Bad odour (rotten egg smell = unmistakable)
- Pink, green, or cloudy discoloration inside
- Heavy condensation inside carton (moisture can allow bacteria growth)
4. Why do we store our eggs in the refrigerator when people in other countries don’t?
Different countries have different approaches for controlling salmonella in or on eggs. Egg production practices, egg washing and hen vaccinations are are just some of the differences. For example, in North America, eggs are washed before candling, grading and shipping while in Europe they are not washed prior to packing. The EU requires salmonella vaccination for all hens while Canada does not.Â
When eggs are washed, the natural protective coating (the cuticle or bloom) that comes from the hen is removed. That leaves the porous shell of eggs vulnerable to bacteria like salmonella. To prevent that risk, washed eggs must be stored in the fridge.
In North America, if you buy commercially grown eggs from a grocery store, keep your eggs in the fridge to reduce the risk of salmonella growth.
For optimum freshness, store eggs in their original carton in the main part of the fridge, not in the fridge door or in the egg caddies.
5. What came first, the chicken or the egg?
The chicken came first. British researchers confirmed the formation of eggs is only possible due to a protein found only in chicken ovaries. The only mystery remaining is where did the first chicken come from? Many are speculating it came from the other side of the road!
6. How can you tell if a raw egg is fresh?
Here are a couple of ways to test if an egg is fresh or old.
Water Float Test
Eggs are porous. As they age, oxygen enters the egg causing the air sac on the wide end of the egg to get bigger. Placing eggs in a jar of water will give some indication of how big the air sac is.
Fresh eggs – air sac is small and eggs lie horizontally along the bottom of the jar.
2-3 week old egg – air sac is growing and eggs start to balance on the pointy side.
Old eggs – air sac has grown to the point where egg will float. Â This egg is about 4 weeks old. To check if it’s still good to eat, crack it open in a separate bowl. If it looks or smells bad, toss it, otherwise use in baking.
The Cracked Egg Test
Crack an egg on a flat plate and observe the yolk and the thick egg white immediately surrounding the yolk (there are two parts to the egg white – the thin egg white and the thick egg white). Â If the egg yolk is nicely centered in the thick egg white which has a definite shape and has some height (as in the photo above), you have a high quality, fresh egg. Â As the egg ages, the thick egg white will become runnier and will become flatter. It’s still good to eat, it just won’t look as pretty if you’re serving sunny side up fried eggs and it might not provide as much “lift” in meringues or angel food cakes.
Extra fun fact – fresh eggs are best for poached eggs and older eggs are best for easy to peel hard boiled eggs.
7. What is that green ring around egg yolks when they’re hard boiled?
That’s a sign of an overcooked egg. High, prolonged heat causes the sulfur from the egg white and the iron from the
yolk to have a reaction which forms a grayish green ring around the yolk. It is harmless and perfectly safe to eat, but not very attractive.
Read my post on How to Make Perfect, Easy to Peel Hard Cooked Eggs for more details on how to avoid the green ring and produce lovely hard cooked eggs that are easy to peel.
Can you hard cook eggs in the oven? I wasn’t impressed with the results when I tried it, as I share in my article on Hard Cooked Eggs in the Oven: Not All They’re Cracked Up to Be.
But do cook eggs in an Instant Pot. Results are fantastic and easy to peel!
8. What is a double yolk?
The formation of an egg is a pretty spectacular process and may take a young hen a little time to get perfect. A double (or more) yolk occurs most frequently in young hens who are just starting their egg laying, or in older hens who are finishing their egg laying career. As their bodies adjust, they may release more than one yolk at a time, which gets encased in the same egg white and egg shell. Double yolks are said to bring good luck. Enjoy and count yourself lucky!
Most often, double yolked eggs are removed from the Grade A table eggs sold in stores. So you’re really lucky if you get one! These eggs are used in processed eggs along with those that are too big, too small or have any other imperfections.
9. Do blood spots mean an egg was fertilized?
Blood spots can occur in any type of eggs – fertilized or not. They are perfectly harmless and are not a sign that an egg has been fertilized. They occur if there is a small ruptured blood vessel in the hen as the egg was being formed. Blood spots are usually detected when they’re graded and candled, however, they may be difficult to see, especially in brown shelled eggs. It is okay to use these eggs. You can remove the blood spots if you wish, but it’s not necessary.
Roosters are not part of commercial egg production, so you’ll never get a fertilized egg from grocery store eggs. If you’re getting eggs from a small farm where the roosters are strutting their stuff, it’s very likely you’ll get a fertilized egg. However, because farmers collect eggs daily and hens do not brood, the growth process is halted very early with no tell tale signs. These eggs are safe to eat and you won’t notice a difference.
10. What’s the best way to peel eggs?
Here are several tips for getting easy to peel eggs:
- Use eggs that are over 1 week old, as eggs age they become easier to peel. The egg white is easier to remove from the shell due to more air entering the egg and reduced acidity.
- Hard cook eggs – don’t overcook or boil them.
- Immediately after draining hot water, shock them in cold water with ice cubes for 10 minutes.
- Gently crack the eggs to give them hairline cracks as they’re cooling in the ice water. A little water will get in between the membrane and the peel making them easier to peel.
- Tap the egg gently all over the shell to get many little pieces. Tap gently to avoid piercing the egg white with the shell pieces.
- Once you have tapped the egg all on every side, use your palm to gently roll the egg between your hand and a table or counter top. You should begin to feel the shell and egg white separating slightly.
- Start peeling from the wide end where the air bubble is. Once you have a good start, the egg should be fairly easy to peel.
- If additional help is needed, peel the egg under running water, letting the flow of the water help separate the egg from the shell.
Video: How to Make Easy-Peel Cooked Eggs
We just had to try it! Given the amount of effort and how much mouth contact was involved – we decided it was a fun, one time experiment. We have not used this technique since!
11. What size egg to use?
The standard for recipes are large eggs. In case you don’t have the right size here are some egg conversions for you:
Egg Conversions Based on Large Eggs
Whole Eggs
3 whole eggs = 1/2 cup
1 whole egg = 3 tablespoons
1/2 whole egg = 4 teaspoons
Yolks
6 to 7 egg yolks = 1/2 cup
1 egg yolk = 1 tablespoon
Whites
4 to 6 egg whites = 1/2 cup
1 egg white = 2 tablespoons
Dried or Powdered Eggs
1 egg = 2 tablespoons egg powder + 2 tablespoons warm water
Liquid Egg Substitute
1 egg = 1/4 cup egg substitute
2 eggs = 1/2 cup egg substitute
4 eggs = 1 cup egg substitute
Special thanks to the Canadian Home Economics Foundation for their support in helping me share ideas for making home cooking easy and enjoyable! The depth of research that went into this post, wouldn’t be possible without their support.
More egg tips and recipes
Cook with the seasons, effortlessly! I’m Getty, a food educator and Professional Home Economist, helping you select, store, and serve seasonal ingredients in delicious, simple, everyday meals. Sign up for seasonal tips and recipes delivered straight to your inbox, and dive deeper with my books, guides, or YouTube content.