15.1 Grades, parts and storage

Egg grades

In Canada, every egg must be graded to a set standard. Any shell egg that is imported, exported or shipped between regions for sale must carry a grade. The grade is printed on the carton: Grade A and Grade B show the grade name inside the grade mark, while Grade C and Nest Run show it in plain block letters.

A grade tells you about quality, not size. The grade mark also does not promise where the eggs were laid; it promises that they meet the standard. Every egg-processing plant is inspected for wholesome, sanitary work, and the pasteurizing of packaged egg products is watched over too.

Graders judge each egg on these points:

• its weight;
• how clean the shell is, and whether the shell is sound and well shaped;
• the shape of the yolk and where it sits, and the size of the air cell;
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• whether there are blood spots, or a yolk that has broken down inside the egg.

Egg grades.

Only Grade A eggs are sold by size, and the size comes from the weight of the egg in its shell. An average large egg weighs about 56 g (2 oz).

Sizes for Grade A eggs.

What is inside

The yolk and the white are built very differently. The white is mostly water with a little protein and almost no fat. The yolk is about half water, and nearly a third of it is fat.

What an egg is made of, by weight; there are also traces of sugar and ash.

All of an egg's cholesterol sits in the yolk. The yolk is fairly rich in iron, while the white is high in calcium. Eggs also carry plenty of B vitamins and amino acids.

When you separate large eggs, a working estimate is 30 g (1 oz) of white and 20 g (0.7 oz) of yolk per egg. Another split is slightly different: 55 g for the whole egg, 38 g of white and 17 g of yolk, with no fat or cholesterol at all in the white.

Shell color, creamy white or brown, depends only on the breed of hen; the egg inside is no different. Yolk color depends on what the hens eat. Bakers like dark yolks because the cakes look richer. Tests found that darker yolks gave moister sponge cakes, but the crumb was a little coarser and less tender.

Storing eggs

A whole egg is an ideal place for bacteria and mold to grow. An egg that smells wrong may be carrying a lot of either. Baking drives off some of these smells, but a strong one can stay and spoil the taste of the finished product.

Eggs, fresh or cooked, count as a potentially hazardous food (PHF): a food that spoils at room temperature and lets germs grow. The critical control point for refrigerated storage is 4°C (39°F) or colder. see chapter 2: Refrigerated storage

• Keep fresh eggs in the refrigerator in their cartons. The carton stops them losing moisture and picking up smells from other food.
• Keep liquid eggs and cracked eggs refrigerated at all times.
• Use eggs while they are fresh. Eggs kept too long before use can cause food poisoning.
• An egg that has gone off turns darker and smells foul.

Testing for freshness

There are two quick checks for a whole egg.

• Candling. In a dark room, hold the egg up to a light so you can see inside. If the white holds the yolk firmly as you turn the egg, and the shell is clean and whole, the egg is good. A bad smell will not show up this way; you only find it once the shell is broken.
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• Salt water. Dissolve 100 g of salt in 1 L of water (3.5 oz in 1 qt). Put the egg in. A fresh egg sinks to the bottom; an old one floats up to the top.
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Quality you can see once it is cooked

Each plain egg dish has a standard it should reach. A good fried or poached egg starts with a good egg: a thick, compact white and a yolk that stands up tall.

• Fried: the yolk sits in the middle, unbroken, under a thin film of set white. The white is shiny and opaque, with no bubbles and no crisp or brown parts. The yolk has thickened but does not run. The flavor is mild, with the taste of the frying fat.
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• Poached: the same yolk and film of white, with a shiny, compact white that has no ragged edges.
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• Cooked in the shell: a white that is firm but still tender, and a yolk that is mealy, centered and has no green ring around it.
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• Scrambled: moist, tender, fluffy masses, all one light yellow.
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• French omelet: set but still moist and tender, with little or no browning on the outside.
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