Aperçu of An Egg

Recently, from small farmers to urbanites and in between, there has been a marked upsurge in local egg coops. Backyard hatcheries are sprouting up across the country. Home-raised fresh eggs from well fed and exercised hens with rich, dark yolks and intense flavors and textures are in vogue. Some of this movement is cuisine based, others find pleasure in raising their own stock, but still others are drawn to home coops due to concerns about the health and welfare of egg layers shoved into cramped quarters on fetid farms. Cries of cruelty and abuse in the egg industry have been heard. Admittedly, the thought of a dozen lifer hens crammed into a cage the size of an oven does make me cringe. Then again, this is a nation that takes perverse pride in lengthy, overcrowded incarcerations–at shameful rates that dwarf other societies. Not exactly the land of the free range.

But what of a glimpse at a hen egg’s oological self? Its anatomy and architecture?

The hard outer shell, composed mainly of calcium carbonate, has several thousand pores which allow moisture and gases to permeate in and out of the egg. This porous structure also can leech foul fridge odors, so store eggs in their cartons. Directly inside the exterior shell are two other protective membranes, the testa and mammilary layers.

Chicken eggs emerge in varying shades because of pigments which are deposited as the eggs travel through the hen’s oviduct. The pigment depositions are determined by the bird’s genetics, with eggs ranging from deep brown to pale blue to pink to green to cream to white. Although not always consistent, chickens with white ear lobes tend to produce white eggs, while those with red ear lobes lay brown eggs. Classic white egg laying breeds include Andalusians, Faverolles, Dorkings, Leghorns, and Lakenvelders. Barnevelders, Rhode Island Reds, Jersey Giants, Delawares, and Orpingtons are known more for brown eggs, which vary in hue from light cream to dark brown.

When the egg is freshly laid, the shell is completely filled. An air cell is formed at the wide end by contraction of the contents during cooling and by the loss of moisture. The smaller the air pocket, the better the egg.

The white, or albumen, is composed of 90% water with the remainder protein. The outer white is the thin edge of the white which cooks more quickly than the center. The inner white is thick and firmer than its cousin on the edge. The white’s ability to form a relatively stable foam is crucial to the development of structure in dishes such as angel food cakes, soufflés, and meringues. It also serves as a clarifier and binder.

Chalazae [kuh-LAY-zee] are a pair of spiralled cords that anchor the yolk in the center of the thick albumen. Chalazae may vary in size and density, but do not affect either cooking or nutritional value.

The clear yolk membrane (vitelline membrane) surrounds and cushions the yolk. An egg’s yolk delivers vitamins, calories and nutrients, including protein and essential fatty acids along with a natural emulsifier called lecithin. Yolk color ranges from light yellow to deep orange usually depending on diet. The germinal disc, or nucleus, appears on the surface of the yolk as a white dot. Yolks are critical to sauces such as mayonnaise, hollandaise and some vinaigrettes, even pastas and soups.

P.S.  Note the rooster that adorns the top of the “D” on the Food Day logo.

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