By Annabel Slater
Does egg yolk colour matter? Why are yolks from hens in different countries different colours? Find out with FoodUnfolded.
When I was growing up, we used to keep free-range chickens. We’d buy them from battery farms – gawky young birds with missing feathers and blinking greyish-yellow eyes that had never seen sunlight. When let outside for the first time, they’d voraciously peck at anything green and living.
As they settled into their new life, everything about them changed. Their combs turned from anaemic pink to rich vibrant red, stubbly feathers blossomed into patterned plumage, and the yolks of their eggs turned from pale whitish yellow to a deep amber colour.
What could be clearer? Regular sunlight and country living produced happy, healthy hens and eggs that were bursting with colour.
Well…I was both wrong and right.
WHY ARE EGG YOLKS YELLOW OR ORANGE?
Egg yolks get their colour from carotenoids. Carotenoids are plant pigments, responsible for red, orange and yellow hues in certain vegetables and fruits. You might guess then that carrots, pumpkins, peppers, Vietnamese gac fruit, and sweet potatoes are all particularly rich in carotenoids.
But carotenoids are also found in green plant material, because carotenoids absorb light for photosynthesis and protect the plant from sun damage. The reason some trees turn brilliant shades of yellow and orange in autumn is because you can see the colour of the carotenoids as the green chlorophyll disappears.1
CHICKEN’S DIET CHANGES THE EGG YOLK COLOUR
o, our free-range chickens gained carotenoids from the grain, grass and plants they ate. Their yolks changed colour because carotenoids accumulate in fat, and about a third of the yolk is fat.
This means carotenoids can also colour animal fat tissue – including your own. If you ate an excessively high amount of squash, you would develop carotenemia – orange-tinted skin!2 If that’s hard to imagine, just look at flamingos. Their pink-orange feathers are made from fats rich in carotenoids from the shrimp and algae they eat.3
ARE YELLOW EGG YOLKS BETTER THAN ORANGE EGG YOLKS?
Continue reading: Orange Egg Yolks: Why Are Some Egg Yolks So Orange?