It's an Egg of a Different Color! Why Shell Hues Vary
A good friend of mine raises chickens and regularly surprises me with eggs straight from the henhouse. With their oversize orange yolks and superior taste, these ova outdo a dozen from H-E-B any day of the week.
These farm-fresh eggs also outshine supermarket eggs in terms of appearance, as well as taste, for their shell colors are far more interesting than the off-whites and browns you'll find in standard cartons.
How do some eggs come to sport snazzier shells than others? A little bit of nature, a little bit of nurture.
Photo by YoVenice I shudder to think how much scientists would have to genetically modify a chicken to produce these eggs.
Simply put, different breeds of chickens produce eggs of different hues. The process by and degree to which an eggshell (which always starts off white) acquires color is determined by genetic markers.
An eggshell's color, however, is subject to more than genetic influences. Diet plays a large role in eggshell color; for example, chickens that eat a lot of clover tend to produce eggs with sunny yellow shells. Some studies have also shown that the temperature of water consumed by nesting fowl can increase the chances of darker-colored eggshells.
More subtle shell markings have even more complicated origins because the size of the egg and the speed at which it passes through the chicken give rise to varying splotches, streaks and speckles.
Technically, eggshell color does not determine the egg's flavor, so don't discriminate based on hue when choosing omelet ingredients. However, given that all the aforementioned factors are capable of altering an egg's exterior, it's not unlikely they also can influence the interior.
Chickens subject to stress (hello, factory farms!) and fear have been observed to lay paler eggs due to the release of certain hormones. Perhaps one more reason to eat free-range? I don't imagine angst-ridden eggs are appetizing.