Saturday, October 31, 2009
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