Food scientists reveal what the yolk color says about eggs

Eggs-perts are weighing in on the color of your egg yolk.

As Americans down an average of nearly 300 eggs a year, you’ve likely cracked open an egg to see a yolk slightly different than what you’re used to, whether a bright orange or pale yellow yolk.

“Egg yolk color can range anywhere from almost white to a blood-red color,” Richard Blatchford, PhD, a poultry researcher and associate specialist in Cooperative Extension: Small to Industry Scale Poultry at the UC Davis Department of Animal Science, told Food & Wine.

“But the extremes are pretty rare to see.”

One shade isn’t necessarily better than the other, but the different shades do have a meaning, particularly regarding how the hen was raised.

Poultry experts track yolk colors using the DSM Yolk Color Fan, a 16-scale color index used in the industry to mark yolk color, with each number corresponding with a different shade.

Sunoh Che, DVM, PhD, assistant professor of poultry management at the University of Maryland, told F&W that while many aspects can affect the color of an egg’s yolk, it mainly comes down to the hen’s feed and diet.

“Hens with access to fresh grass and pasture tend to produce eggs with more vibrant yolk colors,” Che said, adding that these hens get sources of protein from bugs, as well as carotenoids and xanthophyll from plants.

Poultry experts keep track of yolk colors using the DSM Yolk Color Fan. Reflexpixel – stock.adobe.com

“Not all plant material is equal when it comes to containing xanthophyll — some have higher concentrations and different types,” Hillary Ayers, family and consumer sciences agent with University of Florida, Institute of Food and Agricultural Sciences Extension Orange County, said.

The amount of yellow-orange carotenoids (plant pigments) in the hen’s food — such as lutein from alfalfa meal and zeaxanthin from marigold flower extract — “significantly affects yolk color,” Che explained.

Corn is another ingredient that can affect the color. “Hens that make grocery store eggs are usually fed a corn-based diet,” Blatchford added. “That’s why most of our grocery store eggs are a yellow color, but not really bright.”

The amount of yellow-orange carotenoids (plant pigments) in the hen’s food “significantly affects yolk color.” New Africa – stock.adobe.com

Here is what the color of your yolk means, according to Jen Houchins, PhD, RD, director of nutrition research at The American Egg Board’s Egg Nutrition Center:

• Pale yellow: A pale yellow yolk signifies a diet heavy in wheat, barley or white cornmeal.
• Bright yellow: Bright yellow or yellow-orange yolks mean that the hen had a diet with a lot of corn and/or alfalfa meal.
• Orange: A deeper orange yolk can come from a diet that includes foraging, “where hens can access different plants and insects whose pigments can impact color.” Hens tend to be outside more during the spring and summer, which increases the probability of foraging. This color can also be produced by adding marigold petals or red pepper to the hen’s food, though Houchins noted that artificial color additives are not allowed in the U.S.

Even though yolk color is determined largely by the hen’s diet, it doesn’t necessarily affect yours.

“The nutritional content of eggs — including fat-soluble vitamins A, D, E, and K — depends more on the hen’s diet, health, breed, age, and environment than on yolk color,” Che shared.

“Pasture-raised hens often produce eggs with higher levels of nutrients like omega-3 fatty acids and vitamins due to their diverse diet, not the intensity of yolk color.”

However, Houchins added that yolk color can determine how much carotenoids are in an egg, which is linked to good eye health, as well as lowered risk of cancer, diabetes and bodily inflammation, according to the National Institutes of Health. The deeper the orange, the more carotenoids the egg likely has.

“Beyond carotenoids, though, yolk color does not indicate a more or less nutritious egg,” Houchins said.

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