Sometimes, I think eggs are the perfect food. They are certainly very versatile, mostly because they have two major components giving three different ingredients: eggs, egg whites and egg yolks.

The egg yolk makes up 30% of the egg. It is full of nutrients including fat (and cholesterol), protein, iron, vitamins A and D. In a fertilised egg, the embryo grows within the yolk drawing from its nutrients, which is why it is so full of fat and protein.

A healthy egg yolk should be firm and translucent. When it is still part of the egg, it should sit centrally with a high dome. The colour of the yolk is determined by the colour of the chicken’s diet and has no bearing on its nutritional value. The yolk from a free range chicken will tend to be paler than that of caged birds.

Egg yolks can be frozen, however they tend to become slimey when defrosted. This can be avoided by mixing in either salt (at a ratio of 8:1000) or sugar (at a ratio of 48:1000) before freezing (depending on intended use for the yolks).

Egg yolks coagulate at 65-70°C (150-155°F). Egg yolks should not be cooked at a higher temperature, as they may become chalky and hard.

Yolks are prized in culinary pursuits because of their ability to:
bind - egg yolks (separated or as part of a whole egg) are often added to recipes to hold ingredients together because of their sticky texture;
emulsify - egg yolks are the basis of both cold emulsion sauces (e.g. mayonnaise) and warm emulsion sauces (e.g. bearnaise sauce), because of its ability to hold together ingredients that do not normally combine;
thicken - egg yolks thicken custards and can be used to thicken soups and sauces; and
enrich - egg yolks can be added to recipes for nutritional, flavour-enhancing and colouring purposes.

Egg yolks are often used to achieve more than one of the above. For instance, they can be used in making pasta for colour, flavour and to help bind the pasta together.

So you have just made a pavlova, and you might be wondering what you can do with the leftover egg yolks. Suggestions include: custard, mayonnaise, ice cream, crème brûlée, bavarois.