Anatomy of an Egg

Shell Bumpy and grainy in texture. An eggshell is covered with as many as 17,000 tiny pores. It is a semi-permeable membrane, which means that air, odors, and moisture can pass through its pores.

Inner and Outer Membranes Lying between the eggshell and the egg white, these two transparent protein membranes provide efficient defense against bacterial invasion. They’re partly made of keratin, a protein that’s also in human hair.

Air Cell Air space forms when the contents of the egg cool and contract after the egg is laid. The air cell usually rests between the inner and outer membranes and at the egg’s larger end. The air cell grows larger as an egg ages.

Albumen The egg white is known as the albumen. Alternating layers of the albumen contain approximately 40 different proteins and water.

Chalazae Thick ropes of egg white, the chalazae hold the yolk in the center of the egg. Like anchors, they attach to the yolk’s membrane and to the lining in the eggshell.

Vitelline Membrane A clear membrane that encloses the yolk.

Yolk The yolk contains protein, water, some fat, and most of the vitamins and minerals of the egg. These include iron, Vitamin A, Vitamin D, phosphorus, calcium, and B Vitamins.

Yolk Yolk color ranges from a hint of yellow to a deep orange, according to the feed and breed of the hen.

More Egg Notes… One egg = 1 ounce of lean cooked meat = Eggs are the best source of complete proteins with lots of vitamins and minerals.

More Egg Notes… Many experts recommend limiting the use of egg yolks and whole eggs because they are high in cholesterol. Egg whites are cholesterol free. ◦ For this reason, many people use egg substitutes.

More Egg Notes… Cracked eggs can contain harmful bacteria which can cause foodborne illnesses. Discard any eggs that become cracked or broken during transportation or storage.

More Egg Notes… Store eggs in your refrigerator. Fresh eggs can be stored for 4 to 5 weeks in the frig.