Friday, January 31, 2014

What the Color of an Egg Yolk Can Tell

Consumers prefer eggs with a rich, bright-yellow yolk, and some places, like Southern Europe, they prefer them even darker orange-red. Meanwhile some markets, like African villages, are used to pale off-white egg yolks. How do the living conditions, diet, and external manipulations of hens bring about the desired rich colors in egg yolks, and do the rich colors really add more flavor and nutrition? It's more of a complicated equation than you might think.
Hunter Communications Original News Source:  
Dutras' The Paper

Link to article: 
Modern Farmer: Marketing Colored Egg Yolks

Excerpt: "Ask a backyard chicken farmer what the best part of owning hens is, and you’ll probably hear something about the egg yolks. Their chickens’ yolks are a rich and satisfying shade of orange, and the yolks of those $1.79-a-dozen commodity eggs literally pale in comparison.

To hear such crows of superiority, you’d think that hipster hen keepers invented brightly-colored yolks. But consumers have shown a preference for strikingly colored yolk for at least a century, and egg producers have been catering to this trend for just as long.

In a 1915 paper in the Journal of Biological Chemistry, Dr. Leroy Palmer identified the chemical culprits behind yolk coloring.

'The consumer demands highly colored yolks in ‘fancy’ eggs throughout the year, and the eggs with pale colored yolks, so frequently found on the market during the winter months, are the object of much complaint, particularly in cities,' Palmer wrote. He found that yolk color is determined by a class of carotenoids called xanthophylls. Nearly 100 years later, this conclusion is still widely accepted.

Carotenoids are pigment molecules produced primarily by plants, and are only available to animals via diet. They include precursors to vitamin A, and many have been shown to have antioxidant capabilities.

Historically, pale egg yolks were often taken as a sign of sick or malnourished hens. But it’s not always the case. In many African countries, white corn is typically a part of chicken feed. White corn (or maize) is low in carotenoids and hens that eat it can produce eggs with yolks so pale they’re almost off-white, despite the chickens being well nourished and healthy.

And contrary to what you may learn at the farmers market, richly colored yolks are not universally preferred. Consumer demand for various yolk colors varies by region. According to the UK website http://www.yellow-egg.com/: 'Where the color of egg yolks is concerned, Europeans are not unanimous. A real North-South divide can be observed. While the northerners prefer pale yellow yolks, the preference of consumers for golden-yellow yolks grows as we go further south. On the shores of the Mediterranean, only bright, orange-red yolks stand a chance of reaching the plate.'

In Italy, eggs are named according to the color of their yolks, with yellows being referred to as giallo dell’uovo, and the orange yolked eggs called rosso d’uovo.

There is an egg yolk color identifier, called the DSM yolk color fan. Formerly known as the Roche Yolk Color Fan, it looks similar to the paint color fans from the hardware store, and contains 15 shades along the yellow-to-orange spectrum, and is the industry standard for assessing and comparing yolk color.

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