The opaque, viscous orange centre of an egg, intended to feed the developing embryo. Egg yolks have a lower water content than the white that surrounds them, but contain higher levels of protein and significantly more fat. They have a much richer flavour, and are used to thicken sauces such as mayonnaise and custard. Contrary to popular myth, the colour of an egg yolk has no bearing on its quality – it simply reflects the breed of the hen, its diet and the time of year at which it was laid.
Separated egg yolks can be kept in an airtight container in the fridge for a couple of days. If you wish to freeze them separately, mix them with either sugar (for use in sweet dishes: one tablespoon sugar per 568ml/20fl oz yolks) or salt (one teaspoon per 568ml/20fl oz yolks) or they will be thick and difficult to handle once defrosted.
Although egg yolks are high in cholesterol, there is no evidence that this leads to heart disease.
Article by Felicity Cloake