asked via Twitter: Why do hardboiled quail eggs turn translucent when frozen and white again when defrosted?
It’s a funny thing, seeing through something. We have an expectation that, by default, we can’t see through things, because many things that we see are, well, not something we can see through. Another way of thinking is that seeing something is the exception to what normally happens. It’s Newton’s First Law of Motion: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
Light follows this rule as well: it goes forward until it hits something that causes it to change direction: an apple, a bit of dust, some water, wood, very small rocks, and a duck. In most cases, some of the light reflects back to us, and that gets turned into color. In other cases (glass, water) the light just changes direction a little, which causes things to become offset from what we expect.
So in many ways, we have to think about why we can see things, rather than why we see through them. We see things because their molecular structure is dense enough that light can’t get through it, and instead is reflected off of it or refracted through it. If you have big enough gaps in-between the molecules, though, the light can just sail right through.
Which is all well and good, but how does it tie in with egg whites? Egg whites have a lot of water in them. Fresh egg whites moreso than, as they say, “old friends,” but still plenty of water is in there. When they’re uncooked, the egg whites are pretty well transparent, but after you cook them, the proteins unfold and spread out, which causes them not only to become more rigid, but also more opaque. Still, there’s not enough protein matter to fit in-between every molecule water, so if you freeze the egg whites, the water forms ice crystals. The weird thing about water is its insistence on taking up more volume as a solid than it did as a liquid, whereas almost everything else does the opposite. This has to do with the shape of the crystal that ice becomes, which just happens to be big and bulky.
Because of all this space that ice takes up with the same number of molecules as from its liquid phase, there’s more space in-between the protein molecules. So the more water there was, the more ice, and thus, you end up with a transparent egg white.
The phenomenon is not restricted to quail eggs, it happens with chicken eggs, and probably most other eggs as well. The difference between them is the amount of white in the egg itself. Because a quail egg is tiny, there’s hardly any white, so there’s less chance that the light is going to be blocked. Thus, it’s much more likely that you’ll be able to see through the white all the way to the yolk in a quail egg as compared to a chicken or ostrich egg.
|Two types of hard-boiled eggs, quail and chicken, in both frozen and non-frozen states.|
Now, the story doesn’t end there. When you thaw the quail egg, it’s still somewhat translucent. Gasp! But if you look closely, you’ll notice that the white has a lot of little holes in it. The ice crystals tore through the protein mesh that formed the solid part of the egg, and when it melted, the protein couldn’t distribute itself around it. If you were to squeeze a thawed quail egg, you’ll get water pouring out of it. Again, this happens with all eggs to one degree or another, which is why we don’t freeze hard-boiled eggs.
Watch the time-lapse video of the eggs thawing next to the non-frozen eggs. Most of the excitement, if you want to call it that, is in the frozen chicken egg, which goes from slightly-translucent to slightly-less-translucent. And you can see some water drip down the side of the egg.