Exacting the Facts About Eggs


February 04, 1996|By ROB KASPER

To keep entertained on these long winter nights I have been trying egg tricks. It began with a Caesar salad. One of our kids tasted his first Caesar salad at the home of some friends who, in the Maryland tradition, held an open house on New Year's Day. The kid regarded this new dish as among the best foods he had ever eaten. Reacting to the unlikely occasion of a kid's being enthusiastic about salad, we began making Caesar salad for supper.

To make Caesar salad you have to break an egg. The first recipe we tried called for breaking the egg and mixing it in with the salad after the egg had been boiled for 60 seconds. The egg was placed in the boiling water.

A debate then began among family members over whether the contents of this egg were "hard-cooked." The central question was how could we find out, without breaking the shell, whether the insides of this egg were solid or liquid.

That is when I pulled out the spin-the-egg trick. I had read that a hard-cooked egg would spin, on its pointed end, like a top. Conversely, an egg with a soupy center would, I had read, fail to spin.

The egg-spinning episode did not work out in practice the way it was described in print. The 60-second egg did not spin, nor did an uncooked egg I had pulled from the fridge. But an egg I had hard-cooked for several minutes turned out to be a so-so spinner. It made a determined start, then it wobbled and fell.

Still, there was a marked difference between the spinning ability of the hard-cooked egg, the egg that was uncooked, and the one cooked for just 60 seconds. The hard-cooked egg stood on its tip and gave the spin the old college try. The uncooked and 60-second eggs couldn't even stand up.

The trick proved that the 60-second egg, which we were about to crack over the Caesar salad, still had a liquid interior. Rather than being impressed by the brilliance of this magic, members of my family were simply curious. Why, they wanted to know, did a hard egg spin and not a soft one? I had no idea. I knew egg tricks, but egg physics was beyond me.

I called John Doerr, a professor of poultry science at the University of Maryland at College Park. Doerr gave me a detailed explanation of how eggs work. He mentioned the three different fluids in the white of an egg and told me how, in a soft egg, these fluids move at different speeds when the egg is spinning.

The part of his explanation that made the most sense to me was when he compared the spinning uncooked egg with a "goofy ball," a kid's toy designed to wobble as it rolls along the floor. The insides of both the uncooked egg and the goofy ball are not in sync with their outsides, he said, and so won't balance and won't spin. He said that when an egg is hard-cooked, its once free-floating insides are transformed into a solid mass that spins in sync with the eggshell.

He also told me why my hard-cooked egg started to spin, then wobbled off course. The egg I was using, he said, did not have a perfectly symmetrical shell. Some egg shells are symmetrical, some not, he said.

While I had him on the line, I asked Doerr about another kitchen stunt, the floating-egg trick. I had read that if you put an uncooked egg in a bowl of water and the egg floats, it is a "bad egg."

Basically what this trick shows, he said, is that a floating egg is an older egg. He explained that when an egg is freshly laid, it has an air space about 1/16 of an inch wide at the top of the egg. As the egg ages, the air space increases. An egg that has enough air in it to cause it to float to the top of a bowl of water has probably been around for a while.

Doerr cautioned me against labeling something as "bad" just because it is "older." But he said that if he found a "floater" in the eggs pulled from his refrigerator he probably would toss the floater out. Eggs are so inexpensive, he said, there is not much sense in taking a chance with one that might be past its prime.

In the course of my research into egg tricks, I spoke with Elisa Maloberti of the American Egg Board, the trade association of American egg producers. Maloberti informed me that the way I was making a Caesar salad, using an egg that had been cooked 60 seconds in boiling water, was not the approved Egg Board method.

The 60-second boil would not kill any harmful bacteria that might be in the egg, she said. The approved method for making Caesar salad, she said, is to mix egg yolks with wine vinegar, lemon juice, dry mustard and Worcestershire sauce and cook the mixture very slowly until it thickens and bubbles at the edges.

The next time my family made Caesar salad, I used the Egg Board method. My family liked the flavor, but I am sticking with my 60-second-egg way of preparing the dish.

First of all, the risk of getting an infected egg is very small -- about five one-thousandths of a percent, according to the Egg Board.

Second, cooking the egg gives me a chance to try the spin-the-egg routine. I find it hard, in other words, to replace an old egg trick with a new technique.

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