Eggs: Everything You Ever Wanted to Know {& More!}

Yellow Birch Hobby Farm: Eggs: Everything You Ever Wanted to Know {& More!}


The delicious, protein-packed little wonder that turns us poultry raisers into daily treasure hunters. We LOVE our eggs. So when a friend of mine posted an article ragging on the United States for being one of the only countries to sell their eggs in a refrigerated section of the grocery store, I decided to take a closer look. Are they wrong for doing this? What’s the alternative? And in my quest, I discovered that there is a LOT to learn about this seemingly simple little hard-shelled wonder. Which is why I decided to write a complete article on the egg and its nutritional information, how we can store and preserve them, and a whole mess of various facts both useful {and useless!}. 
Are you ready? Let’s answer some questions…and then some.

Anatomy/Egg Production

  •  The yolk is the “heart” of the egg; the origination. It is formed within the hen’s ovary. When she ovulates, the yolk is released from the ovary and then received by the oviduct where the egg is then completed. And to keep with the “ovi” trend, the oviposition is the actual laying of the egg. Within 30 minutes of laying her egg, the hen begins the process all over again, taking 24-26 hours to produce another. 
  • To produce a dozen eggs, a hen consumes approximately 4 pounds of feed! Depending on breed, chickens can lay up to 300 eggs per year, with an average more realistically in the 250 range {and much less, again breed depending}. A handy breed chart like this one can help clue you in to egg productivity based on breed.
  • The inner shell of an egg has 2 membranes, between which the air cell {air pocket} is formed at the large end of an egg. After a warm egg is laid and begins to cool, that air cell expands between the two membranes. As an egg ages, moisture and CO2 escape the shell and are replaced with air, resulting in an ever-growing air cell.
  • The egg’s shell is 94% calcium carbonate, which is why many use ground up egg shells as an alternative to oyster shells for a calcium supplement in hens of egg-laying age.
  • The surface of an egg shell contains as “few” as 7,000 pores and up to a whopping 17,000 pores, more densely populated at the larger end of the shell. It is through these pores that the egg “breathes”. The bloom is the protective coating on an egg shell which prevents bacteria from entering the egg, which is why washing your eggs is commonly advised against, unless you are using them right away. Washing them removes this protective cuticle, thus inviting potential bacterial invaders aboard.
  • Despite what some may say, earlobe color of a hen is not a determinant in egg shell color {although there are some red-eared breeds who lay brown eggs and white-eared breeds who lay white eggs, meaning it is sometimes an indicator of shell color}. Egg color is determined by breed.
  • The yolk is a fascinating thing! The American Egg Board compiled a list of the yolk’s characteristics:

-the yolk makes up for 34% of the liquid weight of an egg
-it contains all of the fat
-contains slightly less than half of the protein
-55 of the average 70 calories found in an egg are in the yolk
-you will find the higher concentration of vitamins in the yolk as opposed to the white, except for niacin and riboflavin
-Vitamins A, D, E, & K are all in the yolk, as well as the B6, B12, folic acid, pantothenic acid, and thiamin
-double yolks are most often seen in young pullets who have not yet reached synchronization in their egg production, but can also be found in layers of extra large eggs or as a result of genetics. 

  • Alternately, the egg white {or Albumen} has its own unique characteristics:
-accounts for 66% of the liquid weight of an egg
-contains the higher amount of protein, just a little more than half
-no fat and only 17 calories
-claims the majority of the niacin, riboflavin, magnesium, potassium and sodium
-although known as the egg white, the albumen is actually more clear or transparent, not turning white until cooking
-consists of 4 different layers 
  • The record number of yolks in one egg is 9.
  • Not only is the egg packed full of high quality protein {for which they are likely the most well known}, but a single egg contains 13 essential vitamins and minerals. They’re a great source of unsaturated fat, antioxidants, and pack 28 mg of calcium- all for just 70 calories apiece. They also provide choline, which when consumed by a pregnant woman aids in enhancing memory function in her unborn child. 
  • Fresh eggs- are they a big deal? I’ve always thought so- and it seems most fellow poultry fanatics out there will agree. The fresh egg is the crown jewel of our chicken-loving existence! But friends, I have some unfortunate news for you: I have been unable to find evidence that fresh eggs are better nutritionally than eggs that are 3 weeks old. Now, before you go throwing the book at me, I must mention that the conditions under which the egg layers are raised plays a key role. Free range, pasture raised, and farm fresh eggs most certainly are more nutritious than eggs produced from caged production birds responsible for store bought eggs. But an egg from my own free range hen today vs. one of her eggs from 3 weeks ago? Little or no difference from what I’ve been able to find. Remember I am talking nutrition, not taste.
  • A common misconception of egg freshness and nutrition is that of its yolk color. You often hear of people comparing the pale yellow yolks of store bought eggs to the orange yolks of farm fresh eggs. In truth, the color of the yolk tells you nothing of its age or nutrition but rather what the chicken was consuming. Free range chickens eat more pigmented foods (and are often spoiled by a handful or so of scratch feed or cracked corn per day), which is then transferred to the egg yolk. Some egg producers have been known to feed their chickens marigolds to darken the yolks of their eggs.
  • So how can you determine freshness of an egg visibly? A cloudy egg white is evident of higher CO2 levels {the fresher the egg, the higher the CO2 concentration trapped in the egg white}. As an egg ages, CO2 escapes through the pores of the shell, resulting in the transparency of the egg white over time. The yolk will also become flatter, thinner, and weaker with age.
  • Additionally, the chalazae {the ropey strands of egg white which tether the yolk in the center of the egg white} which is more prominent equates to a fresher egg. Some people like to remove the chalazae from their egg whites, but that is completely unnecessary.
  • The “Egg Float Test” is a well-known way of determining egg freshness. A fresh egg when placed in a glass of water will sink to the bottom and lay on its side. As an egg ages and the air cell inside the larger end of the egg increases, the egg will start to rise. A 3 week old egg will suspend itself in water with pointed side down, nearly touching the bottom.  An egg that floats to the top of the water {evidence of an aged egg with a large air cell causing it to float} is a sure sign of an older egg. Most will suggest you not consume this egg- others will tell you crack it open and if it doesn’t smell bad, it’s fine. I will leave that part up to you.
Egg Float Test by Yellow Birch Hobby Farm
  • In store bought eggs, each carton is stamped with a “Julian Date”, which is a 3-digit number indicating the day of the year which those eggs were packed. {For example, January 1st would be 001}. Generally your store bought eggs are good for 4-5 weeks beyond this date, depending on the egg supplier. 
This carton of eggs was packed on the 273rd day of the year, or September 30th, with an expiration date of 4 weeks later.
  • Fresh eggs are best for scrambling and producing beautiful sunny-side up eggs due to the fact that a fresh white and yolk hold up much better than an older one, resulting in fluffier scrambled eggs and fried eggs with unbroken yolks. Older eggs, in contrast, are preferred for hard boiling. As the egg ages, its attachment to the outer membrane weakens and as more air is taken into the egg, the air cell increases and the egg white slightly decreases, creating more room between the inner membrane and the shell. This makes for easier peeling! 
  • If you want to tell if an egg is hard boiled or not {without cracking it}, spin the egg on a table. A hard boiled egg will easily spin whereas a fresh egg will wobble due to the moving liquids inside.
Egg Storage/Preservation
  • To answer the question: To refrigerate or not refrigerate? The answer is both yes and no. Do you have to refrigerate? No. But keep in mind that an egg left out at room temperature will age in one day what it takes a refrigerated egg one week to age. Keep in mind too that salmonella flourishes at temps of 40 degrees F- 140 degrees F (ahem, room temperature), whereas salmonella cannot grow at temps below 40 degrees F.
  • The ideal temperature for egg storage is 35-40 degrees at 70-80% humidity. This means you can store eggs in a root cellar maintained at this temperature and humidity (both are important- otherwise simply refrigerate). Gently cover your eggs with warm mineral oil to extend shelf life (if you have large quantities of eggs is really the only time this is necessary). Oil clean, dry eggs (not washed) within 24 hours of being laid for the very best results. Mineral oil will seal the egg and prevent evaporation through the shell’s many tiny pores. Store in a clean egg carton, pointed side down. 
  • As a side note on salmonella, it is most commonly found in the egg white, not the yolk.
  • Did you know that you can freeze eggs and keep them for up to a year? You can freeze them whole or separated by whites and yolks. It is best to freeze in small quantities so that when it comes time to defrost for use, you only defrost what you need. Small freezer containers or ice cube trays work best or even freezer bags (You can pop out frozen eggs from the ice cube trays and transfer to freezer bags or containers). 

-To freeze a whole egg, crack it into your container and stir to slightly incorporate the yolk.
-To freeze egg yolks, you must first expect that they may end up lumpy once frozen. You can prevent this in a couple of different ways by adding salt or sugar based on what you plan to use the yolks for. For general purpose, simply add 1/2 teaspoon salt per 1 cup egg. If they are intended to be used in sweet recipes, you can use sugar instead (1 Tbs). 
-To freeze egg whites, simply separate from the yolk and place in an ice cube tray or freezer container.
-If you freeze in larger quantities, just remember that:
1 whole egg= 3 Tbs.
1 egg white= 2 Tbs.
1 egg yolk= 1 Tbs.

  • Store eggs on one of the inside shelves of your refrigerator rather than in the door to protect them from temperature fluctuation and breakage.
  • Blood spots are often mistakenly assumed to be a sign of a fertilized egg, whereas it is simply a broken vessel on the yolk.
Yellow Birch Hobby Farm: Blood Spot on an Egg Yolk
  • Fertile eggs are considered a delicacy in some cultures, though they are no more nutritious than unfertile eggs. Oddly, I have heard it said that fertile eggs taste better, but I believe this to be purely heresy. 
  • Fertile eggs do not keep as well as unfertilized eggs.
  • The slight depression on the yolk’s surface is called the Germinal Disc. This depression can be seen on all egg yolks, fertile or not, and it is the channel through which the male sperm enters in order to form an embryo.
  • Another common misconception like that of the blood spot, is the assumption that a white spot visible on the egg yolk means that the egg is fertilized. An irregularly shaped white spot is called a Blastodisc; the egg is not fertilized.
Yellow Birch Hobby Farm: Blastodisc on an Unfertilized Egg
  • However, when nicely round and graduated circles are present {having the appearance of a “bullseye” for what they are also known}, this is known as a Blastoderm; this egg is fertilized.
Yellow Birch Hobby Farm: Blastoderm/Fertilized Egg
  • A mother hen turns her egg 50 times a day.
  • Have you ever wondered how a baby chick can grow and survive within an egg? Not surprisingly, the egg is a most ideal environment for them. The thousands of tiny pores that allow the egg to breathe does just that for the growing chick. Moisture escapes, allowing increased room inside for the chick to grow while drawing in additional oxygen. In the 21 days from fertilization to hatching, 8 pints of oxygen are absorbed while 7 pints of CO2 and 18 pints of water vapor are released. No wonder it is called the incredible {edible} egg!
Yellow Birch Hobby Farm: Freshly Hatched Baby Chick
“Lucy” our Quail Antwerp Belgian hen and her two chicks Ruby {left} and Max {front}.

I hope you’ve had some fun today picking up some new information! Who knew something as seemingly simple as the egg could come with so much background and data? Amazing.

And to answer the age old question: What came first? The chicken or the egg? Accordion to the ultimate source of inspired information, The Bible, we find that Genesis 1:20-22 says: “And God said, ‘Let the waters bring forth swarms of living creatures, and let birds fly above the earth across the dome of the sky.’ So God created the great sea monsters, and every living creature that moves, of every kind, with which the waters swarm, and every winged bird of every kind. And God saw that it was good. God blessed them, saying, ‘Be fruitful and multiply and fill the waters in the seas, and let birds multiply on the earth.”

I think we have our answer.

American Egg Board
All Amazing Facts
Sage Hen Farm {Henderson Chicken Chart} 

Shared at:
Down Home Blog Hop #67
The Backyard Farming Connection Hop #60
Clever Chicks Blog Hop #64 
Homestead Barn Hop #139
From the Farm Blog Hop
Farm Girl Friday Blog Hop #136 
The HomeAcre Hop #48 
Simply Natural Saturdays 12/7/13

About yellowbirchhobbyfarm

Hi! I'm Erin, a 19th-century homesteader at heart. Here at Yellow Birch Hobby Farm we practice self-sustainable living by way of organic gardening, canning & preserving, raising a variety of livestock, hunting, foraging, and cooking from scratch. And here at our blog, we share it all with you! So glad you've found us.

9 comments on “Eggs: Everything You Ever Wanted to Know {& More!}

  1. Amazing information, I’ve been keeping my eggs in a carton on the bench but think I’ll transfer to the fridge especially now its reaching warmer temperatures.

  2. Awesome post! You really did your research! I had no idea there was an egg with 9 yolks in it – crazy! I had a double yolker once and it seemed huge. Can’t imagine the poor hen who laid the egg with 9 yolks. Yikes!

  3. Wow. That’s about all I can say. Wow. And thank you. I learn so much from reading your blog. In turn, I can answer all the questions people ask me about our chickens and eggs.

  4. Great list of egg info! I’m pretty new as a farm girl, and this is really timely. It’s nice to find you through the Farmgirl Bloghop! Have a blessed day 🙂

  5. What a wealth of information you are sharing here! I’m so happy to “meet” you and find that you are such an avid chicken proponent. One of my fondest dream is a coop full of hens in every backyard the world over and a fat roaster in every oven. 😉
    I didn’t know about the number of the day the eggs were laid on the egg cartons. That’s a good thing to be aware of. Love your blog, and I can’t wait to read more posts here as I have time. Oh, btw, my Lavender Orpingtons were gotten at a very reasonable price, $6 per day-old chick from a local farmer. I am so happy with them. They are two weeks old now, and in a stock tank in the basement. It appears I may have 2 roos and 2 pullets. So. much. fun.
    Have a great week!

  6. This is all really interesting information! We love our ladies here on our nano-farm, and haven’t been able to buy eggs from the store since we started getting them from the farm a while ago…now if I could just convince them to lay a couple more eggs each week so that I have enough for eating AND baking this time of year…that would be wonderful!

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