Here’s a curious observation: When making hard-boiled eggs, 12 eggs are placed in a pot full of water. 9 sinking eggs are from the same dozen; 3 floating eggs are from a different dozen. All are large eggs; all from the same egg brand. The three eggs may be slightly older than the nine.
What’s happening here? This is more than just a standard deviation of egg density from the average egg! Or else, the observation would be more evenly distibuted.
I’d WAG it’s something about the older eggs, but what?
So, the floaters are the primary source of that tell-tale egg smell esp. when cracking them open? My wife Wagged that the floaters may be suspicious. She just ate the sinkers. (Never thought about this before…and yet, I’m still alive to tell about it!)
Thanks, Jinx
From what I’ve read in at least one cookbook:
Fresh eggs will lay down on their sides when place in water.
Not as fresh, but still “good” eggs will float upright.
Eggs that are too old to be used float.
Hell, I thought everyone knew to perform a float test on eggs before consumption. Float --> chuck, sink --> eat. Its a wonder you havent come down with food poisoning before.
when the egg begins to go bad, the sulfur in the yolk combines with air that permeates the shell and forms sulfide gas (rotten egg smell). An excess of gas in the egg causes it to float. The shell is permeable by oxygen, but sulfur dioxide is a much bigger molecule, so it can’t pass through. That’s why all eggs smell about the same and you have to crack the shell to get the rotten smell. I don’t think you have to worry about food poisoning from any cooked egg (food poisoning would be the salmonella in the egg–destroyed by heat). The chinese bury eggs and let them rot before eating them–a gourmet treat known as “100 year old eggs.” Hasn’t killed the chinese yet. But a rotten egg probably wouldn’t taste very good.
So what are you saying, that the egg shell expands like a balloon? Doesn’t seem very likely to me. Does anyone have any cites for saying the floaters are rotten?
That link could add that the lost moisture and C02 are passed through the shell, which is permeable enough to allow slow leakage. Obviously, since the egg’s volume doesn’t change, if it didn’t lose mass it wouldn’t float however you rearranged the distribution inside it.
Now that I’ve said that, I wonder - is it really that the shell is permeable, or that it develops hairline fractures which allow the passage of material, or do both factors contribute?
What would happen if you coated the egg with a sealant?
the chick in the egg receives its oxygen through the shell, so it’s permeable by oxygen and other small molecules, including water. as the hydrogen sulfide increases in the egg, some oxygen, moisture, nitrogen is lost, reducing the volume of the heavy material in the egg.
If you want to test the permeability of an egg, put food coloring on it and let it set for a while–till it dries, perhaps. Hard boil the egg, remove it from its shell, and note the discolored area under where the food coloring was placed.
An egg can be made nonpermeable if dipped in paraffin or wax.
Uncracked eggs don’t usually rot. They just dehydrate until the innards are completely dried out. Your floating eggs were probably perfectly fine. Eggs keep in the refrigerator for a couple months, easy. The eggs that rot probably have a hairline crack that allowed bacteria to enter the egg.
A couple years ago I talked extensively with a person at a local craft fair who was making those elaborate Ukrainian dyed eggs. She said that they use whole, uncracked eggs. They don’t normally blow out the innards. They just decorate the egg. After it’s sat around long enough it will be dried out. You can shake the egg and hear the powdered egg remains rattling around inside. Very rarely, she said, one will actually rot and explode.
Jinx here again! Just here to say I made a nice egg salad with my three floating eggs which I ate for lunch today…and I’m here to tell about it! My wife claims she did notice the older eggs were smaller (she peeled them for me.) We did not notice any excessive, abundant, nor oppressive “egg smell”.
I agree these floating eggs are harmless. Look how often we’re warned about salmonella poisoning, but who ever heard a warning to always “float test” your eggs before consuming??? Someone said the sulphur is form the yoke, but I was taught the sulphur actually holds the albumen (a protein comprising most of the white) molecule in an “S” shape by weak sulphur bonds. And, when we cook an egg, we break these S-bonds and the albumen then becomes a denatured protein.
About floating, I believe there was at least one (if not more) statement(s) made about volume being lost across the semi-permeable membrane. (Not the volume of the egg shell per se, but, I WAG, they meant the volume of material within the eggshell. In any event, it is more correct to speak of the mass which may either be lost or gained across the membrane. The loss of sulphur from the albumen only to recombine to form hydrogen sulphide would change the density of the egg, and hence (eventually) permit the egg to float.
Interesting story of the rise and fall of the egg (ha-ha) - Jinx
- Jinx