These are the results from the egg poll: 40% of you thought that the yolk would sink, 50% that it would float and 10% had no idea. These data are based in 10 answers, so of course it is nothing scientific. In this case the majority was right: the yolk does float inside the egg. I personally thought that it would sink and was very surprised to see that it didn’t.

There are some membranes that attach the egg yolk to the outer membrane, so it is not completely free to move inside the egg. However, it has enough freedom of movement to go near the upper shell as you rotate the egg and one can see it using the naked eggs we did last week:

Egg yolk floatting in naked egg.

Egg yolk floating in naked egg.

Egg yolk floatting in naked egg, turned 90º.

Egg yolk floating in naked egg, turned 90º.

Egg yolk floatting in naked egg, turned 180º.

Egg yolk floating in naked egg, turned 180º.

The movement as you turn the egg around is quite slow, thus allowing you to keep the egg yolk centered by gently rolling it inside the pan while you are boiling it. The time you should be rolling the egg around depends on how far from the shell you want your yolk to be. This is because the egg is heating from the outside to the inside. As the white heats up, it solidifies not allowing the egg yolk to get any closer to the shell.

I found that for a medium sized naked egg and starting with boiling water, After 2.30 minutes, the thickness of the coagulated layer is a few millimeters. If all you want is that the yolk is not touching the shell, 2-3 minutes of rolling should be enough. After 5 minutes the egg white had a jelly consistency all the way through, so that should be enough to keep the yolk perfectly centered.

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Last week I did one more experiment with the naked eggs, but before I tell you the results I am curious to know what your intuition is about the answer.

Sometimes when you open an egg after boiling it you find that the egg yolk is not centered but has moved to the side, which is inconvenient if you are trying to cook filled eggs. This problem can be avoided by rolling the eggs gently during the first few minutes while you boil them.

Why do you think this happens? Is it because the egg yolk sinks to the bottom of the egg and stays there if you don’t move it around? Or is it because it floats? You have 2 days to vote in my very first blog poll.

Please don’t Google the answer, just reply whatever your intuition tells you (I can tell you that mine was wrong). Otherwise it takes away all the fun.