It’s eggciting for me this week to be able to eggspound on that most eggcellent eggsample of nature’s eggsquisite bounty: the egg. (For one thing, few other topics lend themselves to such eggceedingly eggscruciating eggsamples of eggcessive wordplay.)

I’m going to focus on the chicken egg, although scientifically speaking the chicken egg is only one example among thousands. Fish, reptiles, and even humans produce eggs. An egg, or ovum, is simply the female reproductive cell in sexually producing organisms. It carries genetic information from the mother, which combines with the genetic information carried by the sperm, the male reproductive cell, to produce a new individual.

But of all the eggs produced by all other species, it’s the chicken egg with which we are most familiar. That’s not too surprising, considering 500 trillion of them (500,000,000,000,000, if you like zeroes) are produced every year.

A chicken egg contains of a speck of protoplasm, the germ, from which a new chicken will develop if the egg is fertilized, a large amount of food for the embryo, called the yolk, and additional nutritive material, called the white, made up mainly of a simple protein called albumin. These are encased in a tough double membrane and a hard, three-layered shell, composed primarily of calcium carbonate. The shell protects the egg from the hen’s body weight during incubation.

In a chicken farm, hens are normally housed in wire cages, with two to 10 hens in each cage, and provided automatically with a constant supply of feed and water. The temperature is also carefully controlled. Under these ideal conditions, today’s hens can produce 280 eggs a year. (A few decades ago, 100 a year was considered a good output.)

Before being sold, eggs are graded by size and quality. They’re “candled,” examined in front of a strong light, which reveals defects in the shell, yolk or white. Defective eggs can still be used for commercial egg products, but they’re not sold to consumers.

The freshness of the egg can also be determined by candling. In a freshly laid egg, the white is very thick and opaque. The longer the egg sits around, the runnier the white becomes and the more likely the yolk is to break. The odor becomes more and more “eggy,” and the taste stronger. Through candling, the grader can tell how fresh the egg is by how sharp the delineation is between the yolk and the white.

For just a few cents (and only about 75 calories) apiece, eggs provide high-quality protein, riboflavin, phosphorus, and vitamins A, D and B12. While it’s true that eggs also contain about 213 milligrams of cholesterol apiece (all in the yolk), they are relatively low in saturated fats. Everyone reacts differently to cholesterol in their diet, so while eggs may cause problems for some people, recent studies have indicated that healthy people without cholesterol problems can probably eat eggs without much concern.

Another recent health concern regarding eggs has related to salmonella poisoning. It’s possible for salmonella bacteria to be transmitted into the egg via the hen’s ovaries–which means no amount of cleanliness in the kitchen can avoid it. Since a few outbreaks of salmonella of this type were reported in the northeast U.S. and Great Britain, consumers everywhere have been urged to avoid eating raw or undercooked eggs.

Probably more eggs are used in cooking than are eaten by themselves. Whipped egg whites create a foam that retains air and therefore has a leavening effect. Unbeaten eggs added to an already leavened batter tend to entrap gas and therefore lead to a higher rise. Yolks have their place, too; the fats and emulsifiers they contain have a tenderizing effect.

Even egg shells have their place. Eggs have become associated with Easter because, from the earliest times, eggs have been symbols of fertility and immortality. Brightly colored Easter eggs reflect a folk tale that Simon of Cyrene–the man who carried Jesus’ cross–was an egg merchant. According to the legend, when he returned from Calvary, he discovered that all of his eggs had miraculously turned multicoloured, and were adorned with drawings.

Eggs have worked their ways into our culture in other ways, too. We not only eat them and decorate them, we also throw them, toss them, and even race with them. We call people “good eggs” and we “egg them on,” but sometimes, despite their best efforts, they “lay an egg.”

I just hope this column hasn’t “laid an egg” with you. I’d find that eggstremely eggsasperating.

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