Why are egg yolks yellow?

This is a question we are often asked and it's easily answered. The colour of the yolk reveals what the hen has been eating. The carotenoids in the hens' feed make the yolks yellow. They occur naturally in things like grass, vegetables and fruit. The greater the quantity of these substances in the hens' diet, the stronger the colour of the yolk. The hens ingest yellow pigments in corn or grass, but if they have no access to green fodder (such as hens in cages or sheds) additives are put in the feed to enhance yolk colour.

Some of those additives may trigger allergic reactions in some people and we think that all egg producers who use additives to boost yolk colour should have to clearly state that on their labels. There is currently a review of Australian food labelling laws under way, and we will be making a submission to suggest that if feed additives are used it should be mandatory for them to be declared on the label. If companies don't want to do that ....simple .... don't use additives.
Why we love yellow egg yolks

Our preference for golden yellow egg yolks is rooted in history. Pale yolks were always a sign of sick hens, worm infestation, or poor feed. Only healthy, well-nourished hens store carotenoids (preliminary forms of vitamin A) in their yolks. Bright golden-yellow yolks show that the hens are well supplied with essential carotenoids such as lutein or canthaxanthin. These protective substances are widely found in nature; they not only give the yolk its yellow colour, but also prevent the oxidation and destruction of fragile, vital substances such as vitamins in the egg.
Europeans are not unanimous where the colour of egg yolks is concerned. There is a real North-South divide where  northern Europeans prefer pale yellow yolks, but as we go further south the preference of consumers for golden-yellow yolks grows. On the shores of the Mediterranean, only bright, orange - red yolks stand a chance of reaching the plate.

Not all carotenoids find their way into the yolk. The well-known beta-carotene, for example, is completely converted to vitamin A and metabolized by the hen. Beta-carotene has no effect on yolk colour.

Canthaxanthin, another carotenoid, is different: Birds only convert about 30 per cent of it into vitamin A. The rest is stored in the egg yolk as a protective substance, causing the yolk to take on a golden-yellow hue. As long as this is ingested as part of the hen's naural feed it's fine. Allergy problems can be generated when manufactured and concentrated Canthaxanthin (or other colouring additives) are included in the diet.
There's more information about feed etc in our ebook on the Freeranger website products page www.freeranger.com.au

Egg yolk colour is not a good guide

Most years there is a problem maintaining the rich colour of yolks during summer when there is little green feed around. The majority of egg farms overcome this by putting additives in the feed - but we choose not to include pigmenters in the chook feed.
The colour of the yolk is due to substances called carotenoids. The nutritional value of the egg is not affected in any way by the natural yolk colour but most buyers expect a deep yellow or orange colour - particularly from free range eggs. And that's exactly what our customers get most of the year.
But right now, with the summer heat after an extremely long drought the yolks of our eggs are paler than normal because there is virtually no green feed around.
The most important sources of carotenoids in poultry feed are corn, lucerne and grass meals; these sources contain the pigmenting carotenoids lutein and zeaxanthin.
Unfortunately the carotenoid content in the ingredients of poultry feed is not constant; the pigmentation properties of the carotenoids can be weakened or lost and the fluctuations are out of our control. It is these fluctuations in naturally-occurring carotenoids which push most producers to chase consistency by adding yellow and red carotenoids (such as apoester and canthaxanthin) to the feed. That's something we will never do. If we lose customers just because our yolks are paler than normal for a month or so during dry weather, so be it. We won't compromise our undertaking that we use no chemicals on the pastures where the hens roam and we include no additives in the feed to achieve the desired egg yolk colour.
Producers claim that the colouring additives are natural products. What they mean is that they may be derived from natural products. Virtually all of them are made in laboratories by men and women in white coats.
We choose to feed a corn-based mash supplemented by green feed from our veggie garden when there is no green grass in the paddocks.