Fad or Future

Hatching a plan: how eggs are getting a colour upgrade

With consumer perception top of the agenda, Food Spark looks at the natural ways to alter the appearance of egg yolks.

23 August 2018
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image credit: Masanyanka/iStock/Getty Images

Size, texture and colour are clearly important aspects when it comes to consumer perception of a product. Yellow bananas are seen as the best, despite the benefits of green or even brown ones, and brown sugar, as reported by Food Spark earlier this week, is perceived to be healthier than white.

Yet, there are a number of interesting ways in which the paradigm of perfection is being toyed with. Take the humble egg, for example – specifically the yolk.

Farmers have started to introduce certain foodstuffs into the feed of chickens to naturally modify an egg yolk’s colour, with acclaimed chef Dan Barber one of the first to publicise the idea. Last year, Barber started to feed a red pepper puree to his chickens, found at Cornell University in Ithaca just outside of New York.

The peppers, which were said to have 10 times the normal pigment, naturally coloured the yolks a deep red. The dish in which they appeared was long-windedly called ‘Red pepper egg with everything a chicken eats’ – and in the case of his chickens, that consisted of red peppers, rye grains, herbs, onions, garlic scraps, corn and blueberries.

That concept has crept across the Atlantic, with British chefs experimenting with the method, too. But what’s the science behind this technique and what else can you feed a chicken to naturally alter the yolk?

Yellow fever

The answer lies in a yolk’s carotenoids. These are organic pigments that are produced naturally by plants and algae. They give characteristic colours to a range of different things such as daffodils, carrots and buttercups.

Egg yolks are directly affected by carotenoids, which are ingested by the chicken through its diet. The typical yellow of an egg yolk is attributed to a particular type of carotenoid: xanthophyll.

Xanthophyll is found in grasses, pasture species, cereals, corn, flowers and other normal feed for a chicken. Beyond eggs, it can even impact the colour of chicken skin, legs and beak.

Mainstream egg producers use xanthophyll to regulate colour in mass production.

The concept behind naturally changing the colour of the yolk is simple: change the type of carotenoids ingested by the bird. Red pepper was the eye-catching choice Barber settled on, but there any other candidates.

Colour me yellow

Carotenoids found in carrots also do a job on the yolk, with a deeper yellow colour the result. However, research has shown that chickens lay smaller eggs when given the vegetable.

Another study revealed that tomato powder produces a deeper yellow yolk, with chickens reportedly laying larger eggs and at a greater rate.

Other foodstuffs that induce a deeper yellow yolk include orange peel and greens such as broccoli, spinach and even Brussels sprouts. Paprika has also been known to imbue a rich hue.

Marigolds go the same way as red pepper, turning the yolk a deeper red, as do annatto seeds, while flax seeds are a bit of an oddity, with studies showing it creates a straw-like tint.

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