The is probably the most universal form of food; eggs are found all over the world, eaten at all times of day-breakfast, lunch, tea, and dinner, as well as at picnics and in packed meals-and on every sort of social gathering from the grandest to the most humble.

Edible eggs
Unless otherwise qualified, an egg always means a hen's egg. However, they are not the only form of edible eggs. Other eggs found on the menu range in size from tiny quails' eggs to ostrich eggs' which are large enough to make an omelet for 8-10 people. Guinea fowl, gull, bantam, and duck eggs can also be found commercially with varying degrees of frequency and are worth trying.

Nutrition
Eggs are a valuable source of protein and rich in calcium, iron, zinc, the B group vitamins, and vitamins A, D, E, and K. They are a concentrated source of nutrients and help promote good bones and joints. They also boost the immune system. However, eggs should not be consumed raw and it is advisable for more vulnerable people, such as pregnant and nursing mothers, invalids, the elderly, babies, and young children, to avoid uncooked or lightly cooked egg dishes. Despite the widely help belief, there is no difference in the flavor or nutritional quality between brown and white eggs.

Choosing eggs
Eggs are sold by size, graded into very large, large, medium, and small. As a general rule, choose large eggs for recipes. Very large and large are a good choice for boiling, frying, poaching, scrambling and omelets, while smaller eggs are useful for binding ingredients or for glazing.

Storing eggs
Cool storage is essential to keep eggs fresh, but remember to remove them from the refrigerator 20-30 minutes before use. Store eggs with the pointed end downward-this means the yolk will stay in the center of the egg-and keep the away from strong-smelling foods and flavors. Try not to keep eggs for more than two weeks; instead buy then in smaller quantities to use them up more quickly.

Leftover whites and yolks can be stored in small covered containers in the refrigerator. Yolks, if whole, should be covered with a little water to keep them moist: they should be used within about 24 hours.

Testing for freshness
Very fresh eggs are best for poaching and whisking, and are also easier to separate. Because egg shells are porous, letting moisture evaporate from the whites and air to enter, this forms a pocket between the shell and the lining membrane. The older an egg is, the larger the air pocket at the rounded end of the shell. This acts as a float, so a quick test can be used to indicate the freshness of an egg.

Dissolve 1 tablespoon salt in 1 pint water and lower the egg into it. A very fresh egg will sink and lie on its side. If it lies at a slight angle, it is about a week old and if it tilts straight upward or floats, it is stale.

Another test is to break the egg onto a plate. If the egg is fresh, the yolk will stand clearly above the white, as a plump dome, and the white will have two distinct layers: around the yolk it will be thick and gelatinous, with a distinctly outer layer. A stale egg has a flatter yolk, with less distinction between the two layers of egg white.

Separating eggs
Many recipes require only the white of an egg, or the yolk. Whisked egg whites are used in recipes such as soufflés and meringues as, when cooked, they expand and increase the volume of whatever they are mixed with. The use of egg whites in sorbets has a stabilizing effect, minimizing the formation of ice crystals.

Egg yolks can be used as emulsifiers, holding oil or butter in suspension, keeping the two from separating; the classic example of this is mayonnaise. Egg yolks also act as a binding agent in stuffing, fish cakes, and burgers, holding the surrounding ingredients together.

To separate an egg, tap it against the rim of a bowl to crack it around the middle. Holding the egg over the bowl, carefully open the shell with your thumbs, holding the two halves together to let some of the white run out. Gently tip the yolk from one half of the shell to the other, letting the white run into the bowl and taking care not to break the yolk.

If you are separating more than 1 egg, use a second bowl and tip the whites into the main bowl when separated. If a yolk then breaks, it won't spoil the whole batch of whites. It is important to separate eggs cleanly as even a trace of yolk can prevent the egg white becoming stiff when it is whisked.

Whisking egg whites
A large balloon whisk is the best too to use, since it incorporates as much air as possible into the whites. However, an electric hand mixer will also give good results. Use a large, wide bowl to let plenty of air to be whisked in.

Before you start, make absolutely sure that the bowl and whisk are completely clean and grease-free, since any trace of grease will give the whisked whites a poor volume, and you may find they will not whisk stiffly at all.

Begin whisking slowly until the egg whites are broken up and bubbles appear. Then continue to whisk hard and fast until the egg whites begin to hold their shape. Try lifting the whisk from the mixture-at first the whites will hold soft peaks, bending over slightly. If you continue to whisk, the foam will become stiffer and as you lift the whisk the peaks will form stiff points which stay firm and upright.

Depending on the recipes, whisk the whites to soft or stiff peaks, but take care not to overwhisk. Overwhisked whites become dry and powdery, and it is difficult to fold them into a mixture. Use the whisked whites straightaway as is they are left to stand, the foam will begin to collapse and the whites cannot be re-whisked.

Folding in egg whites
It is important that the mixture into which you are folding whisked egg whites is neither too hot nor too cold, because either can cause much of the volume to be lost. First lighten the mixture by stirring 1-2 tablespoons of the whisked whites-this makes it easier to fold in the rest without knocking out too much air. Use a large metal spoon to fold in the whites, with a cutting and folding action, until the mixture is evenly mixed, with no white clumps of foam remaining.