I have noticed that some duck egg yolks orange while others are yellow. Does that reflect the egg quality? E.g. will dishes made with a dark yolk taste better than the ones with light yolk, or vice versa?
Example of a duck egg with yellow yolk bought in Seattle:
Does that reflect the egg quality?
No
The following applies to poultry eggs in general, not specifically duck eggs.
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.
It depends on what the poultry eats.
There are two classes of carotenoids:
- Carotenes, which tend to produce reddish colours, and
- Xanthophylls, which produce yellow shades.
Farmers can adjust yolk colour through the chickens’ diet. Small scale farmers can directly feed plant material naturally high in carotenoids (e.g. algae, alfalfa, citrus peel, fortified corn), while larger-scale farmers rely on processed feed that contains such ground-up plant material or synthetic supplements.
Processed poultry feed is a blend of grain, protein, vitamins and minerals. In Europe, the EU Register of Feed Additives lists which xanthophylls and carotenes can be added. So, a large-scale farmer has to strike the right balance of yellow and red carotenoids to keep the shade consistent. The types and ratios of carotenoids in feed and eggs will depend on what yolk colour consumers want, and farmers provide.
