- Eggs are laid by many species and have long been consumed by humans. They consist of a shell made of calcium carbonate with pores, two inner protein membranes, an air cell, egg white (albumen) made of many proteins, strands (chalazae) that hold the yolk, a clear vitelline membrane surrounding the yolk, and a nutrient-rich yolk. - Bird eggs have been an important food source throughout history. Chickens were among the earliest domesticated for their eggs, and eggs have been preserved and used in cooking across many cultures and eras. The modern egg industry developed methods for drying and storing eggs on a large scale.

2. EGG
•ARE LAID BY FEMALE ANIMALS OF MANY DIFFERENT SPECIES, INCLUDINGBIRDS,
REPTILES, AMPHIBIANS, MAMMALS, AND FISH, AND HAVE BEEN EATEN BYHUMANS FOR
THOUSANDS OF YEARS.

4. SHELL
• BUMPY AND GRAINY IN TEXTURE, AN EGGSHELL IS COVERED WITH AS MANY AS 17,000 TINY PORES.
EGGSHELL IS MADE ALMOST ENTIRELY OF CALCIUM CARBONATE (CACO3) CRYSTALS. IT IS A
SEMIPERMEABLE MEMBRANE, WHICH MEANS THAT AIR AND MOISTURE CAN PASS THROUGH ITS PORES.
THE SHELL ALSO HAS A THIN OUTERMOST COATING CALLED THE BLOOM OR CUTICLE THAT HELPS KEEP
OUT BACTERIA AND DUST.

5. INNER AND OUTER MEMBRANES
• LYING BETWEEN THE EGGSHELL AND EGG WHITE, THESE TWO TRANSPARENTPROTEIN MEMBRANES
PROVIDE EFFICIENT DEFENSE AGAINST BACTERIAL INVASION. IF YOU GIVE THESE LAYERS A TUG, YOU’LL
FIND THEY’RE SURPRISINGLY STRONG. THEY’RE MADE PARTLY OF KERATIN, A PROTEIN THAT’S ALSO IN
HUMAN HAIR.

6. AIR CELL
• AN AIR SPACE FORMS WHEN THE CONTENTS OF THE EGG COOL AND CONTRACT AFTER THE EGG IS LAID.
THE AIR CELL USUALLY RESTS BETWEEN THE OUTER AND INNER MEMBRANESAT THE EGG’S LARGER END,
AND IT ACCOUNTS FOR THE CRATER YOU OFTEN SEE AT THE END OF A HARD-COOKED EGG. THE AIR CELL
GROWS LARGER AS AN EGG AGES.

7. ALBUMEN
• THE EGG WHITE IS KNOWN AS THE ALBUMEN, WHICH COMES FROMALBUS, THE LATIN WORD FOR
“WHITE.” FOUR ALTERNATING LAYERS OF THICK AND THIN ALBUMEN CONTAIN APPROXIMATELY 40
DIFFERENT PROTEINS, THE MAIN COMPONENTS OF THE EGG WHITE IN ADDITION TO WATER.

8. CHALAZAE
• OPAQUE ROPES OF EGG WHITE, THE CHALAZAE HOLD THE YOLK IN THE CENTER OF THE EGG. LIKE LITTLE
ANCHORS, THEY ATTACH THE YOLK’S CASING TO THE MEMBRANE LINING THE EGGSHELL. THE MORE
PROMINENT THEY ARE, THE FRESHER THE EGG.

9. VITELLINE MEMBRANE
• THE CLEAR CASING THAT ENCLOSES THE YOLK.

10. YOLK
• THE YOLK CONTAINS LESS WATER AND MORE PROTEIN THAN THE WHITE, SOME FAT, AND MOST OF THE
VITAMINS AND MINERALS OF THE EGG. THESE INCLUDE IRON, VITAMIN A,VITAMIN D, PHOSPHORUS,
CALCIUM, THIAMINE, AND RIBOFLAVIN. THE YOLK IS ALSO A SOURCE OFLECITHIN, AN EFFECTIVE
EMULSIFIER. YOLK COLOR RANGES FROM JUST A HINT OF YELLOW TO A MAGNIFICENT DEEP ORANGE,
ACCORDING TO THE FEED AND BREED OF THE HEN.

11. HISTORY
BIRD EGGS HAVE BEEN VALUABLE FOODSTUFFS SINCE PREHISTORY, IN BOTH HUNTING SOCIETIES AND
MORE RECENT CULTURES WHERE BIRDS WERE DOMESTICATED. THE CHICKEN WAS PROBABLY DOMESTICATED
FOR ITS EGGS FROM JUNGLE FOWL NATIVE TO TROPICAL AND SUBTROPICAL SOUTHEAST ASIA AND INDIA BEFORE
7500 BCE. CHICKENS WERE BROUGHT TO SUMER AND EGYPT BY 1500 BCE, AND ARRIVED IN GREECE AROUND
800 BCE, WHERE THE QUAIL HAD BEEN THE PRIMARY SOURCE OF EGGS. IN THEBES, EGYPT, THE TOMB OF
HAREMHAB, BUILT ABOUT 1420 BCE, SHOWS A DEPICTION OF A MAN CARRYING BOWLS OF OSTRICH EGGS AND
OTHER LARGE EGGS, PRESUMABLY THOSE OF THE PELICAN, AS OFFERINGS. IN ANCIENT ROME, EGGS WERE
PRESERVED USING A NUMBER OF METHODS, AND MEALS OFTEN STARTED WITH AN EGG COURSE. THE ROMANS
CRUSHED THE SHELLS IN THEIR PLATES TO PREVENT EVIL SPIRITS FROM HIDING THERE. IN THE MIDDLE AGES,
EGGS WERE FORBIDDEN DURING LENT BECAUSE OF THEIR RICHNESS. THE WORD MAYONNAISE POSSIBLY WAS
DERIVED FROM MOYEU, THE MEDIEVAL FRENCH WORD FOR THE YOLK, MEANING CENTER OR HUB.

12. EGG SCRAMBLED WITH ACIDIC FRUIT JUICES WERE POPULAR IN FRANCE IN THE 17TH CENTURY;
THIS MAY HAVE BEEN THE ORIGIN OF LEMON CURD.
THE DRIED EGG INDUSTRY DEVELOPED IN THE 19TH CENTURY, BEFORE THE RISE OF THE FROZEN
EGG INDUSTRY. IN 1878, A COMPANY IN ST. LOUIS, MISSOURI STARTED TO TRANSFORM EGG YOLK AND
WHITE INTO A LIGHT-BROWN, MEAL-LIKE SUBSTANCE BY USING A DRYING PROCESS. THE PRODUCTION OF
DRIED EGGS SIGNIFICANTLY EXPANDED DURING WORLD WAR II, FOR USE BY THE UNITED STATES ARMED
FORCES AND ITS ALLIES.
IN 1911, THE EGG CARTON WAS INVENTED BY JOSEPH COYLE IN SMITHERS, BRITISH COLUMBIA, TO
SOLVE A DISPUTE ABOUT BROKEN EGGS BETWEEN A FARMER IN BULKLEY VALLEY AND THE OWNER OF THE
ALDERMERE HOTEL. EARLY EGG