Speaker 1: Welcome to brain Stuff from How Stuff Works, Hi brain Stuff,
Speaker 1: Lauren vocal Bomb. Here Peru's the egg section of a
Speaker 1: grocery store of Farmer's Market, and you'll notice cartaons of
Speaker 1: eggs separated into white and brown, and sometimes even green
Speaker 1: or blue eggs. But once they arrive scrambled on a
Speaker 1: plate or baked into a cake, it's tough to tell
Speaker 1: the difference. So what is the difference between eggs with
Speaker 1: shells of different colors? This isn't a situation like rice
Speaker 1: or flour. Brown eggs are not more natural, and white
Speaker 1: eggs have not been dcolored with bleach. Both varieties occur
Speaker 1: completely naturally, as do bluish green chicken eggs. But really
Speaker 1: all chicken eggs are the same on the inside. So
Speaker 1: what causes different egg colors among the same type of bird.
Speaker 1: We spoke with Dr Justin Fowler. We cannot make this up,
Speaker 1: Who's a professor at the University of George's Poultry science department.
Speaker 1: He said, the different colors, or the presence of spots
Speaker 1: or speckling, come down to the genetics of the bird.
Speaker 1: Leghorn chickens, which make up most of the commercial egg
Speaker 1: industry in the United States lay white eggs, while Orphington's
Speaker 1: or plymouth rocks will lay brown eggs. The Amerquana breed
Speaker 1: has a pigment that's able to permeate the whole egg
Speaker 1: shell and make blue colored eggs that are colored on
Speaker 1: both the inside and outside of the shell. So there
Speaker 1: you go. I want to know whether a specific chicken
Speaker 1: will pop out a white egg or a colored egg.
Speaker 1: Examine the chicken's earlobe. Surprise, birds have ear lobes more
Speaker 1: often than not. Chickens with white or lighter ear lobes
Speaker 1: tend to have white feathers and thus white eggs, while
Speaker 1: those with colored feathers and ear lobes tend to produce
Speaker 1: colored eggs. Where does this color come from? Though, Here's
Speaker 1: where Understanding how an egg comes to be is important.
Speaker 1: Chicken yolks or ova form in the chickens ovaries. A
Speaker 1: fully formed ovum will leave the ovary and be deposited
Speaker 1: into the oviduct. This part of the chicken's reproductive system
Speaker 1: has five distinct sequential segments which the yolk passes through
Speaker 1: on its way to the outside world. But it's the
Speaker 1: fourth one, the shell gland, that affects the color of
Speaker 1: the egg. This is where the shell forms around the ovum.
Speaker 1: Fowler explained the process. He said, the shell of all
Speaker 1: chicken eggs are made of calcium carbonate, a crystal that's
Speaker 1: white in color. So all eggs are at least at
Speaker 1: the start white. Any that we then see that our
Speaker 1: other colors have had a pigment deposited on them as
Speaker 1: they were moving through the overduct, after the white egg
Speaker 1: shell had been deposited. You can see this if you
Speaker 1: open up a brown egg and look at the inside
Speaker 1: of the shell, it'll be white. Two pigments are responsible
Speaker 1: for the spectrum of chicken egg color. Shades of greens
Speaker 1: and blues are caused by the pigment bill of vert in,
Speaker 1: while protoporphyrin is responsible for reddish brown hues. The same
Speaker 1: egg coloring process holds true for all birds with colorful eggs.
Speaker 1: American robin eggs, for instance, are famously blue. Oh but
Speaker 1: that egg inside an egg story that you might have
Speaker 1: seen going around the internet, that's another thing entirely, and
Speaker 1: involves an egg accidentally reversing its course in the oviduct. Meanwhile,
Speaker 1: we'll leave you with the answer to a practical egg query.
Speaker 1: Should chicken eggs be kept refrigerated or at room temperature.
Speaker 1: It depends on whether you live in a country Australia, Japan,
Speaker 1: and the United States, for instance, that requires eggs produced
Speaker 1: for commercial sale to be washed. This protects against salmonella,
Speaker 1: but also removes a waxy shell coating that naturally defends
Speaker 1: eggs against micro organisms, thereby necessitating refrigeration. Today's episode was
Speaker 1: written by Christopher Hassiotis and produced by Tristan McNeil and
Speaker 1: Tyler Clang. For more on this and lots of other
Speaker 1: foul topics, visit our home planet, how stuff Works dot com.