Entropy, Eggs, and Energy
I was reading through science news, like you do, when I came across this article about some chemists at UC Irvine who have developed a way to un-boil hard-boiled eggs. The process wasn't developed specifically to turn back the clock on boiled eggs, though, but to "reset" proteins that have been tangled and misfolded through some sort of chemical process so they can be recycled or reused. Medicine, biotech, and food production rely on the steady production of proteins but sometimes the manufacturing goes awry. Currently the only way to reuse the misfolded proteins requires an expensive and time-consuming process. This new one cuts the time and the cost to a small fraction of what it used to be.
And it doesn't really unboil the whole egg, either. It just resets one of the proteins in the egg what to what it was before the heat screwed it all up and solidified the albumen. The protein is lysozyme, which makes up only a few percent of the albumen. The egg isn't completely reset; heck, the egg white isn't even mostly reset, but it's still a really cool proof of concept.
This got me thinking about two things: first, if we're now one step closer to reversing the Maillard reaction and fixing overcooked steaks (probably not) and second, entropy.
Entropy, if you haven't heard of it, is a measure of the tendency of a system to eventually fall into disorder. Sometimes it's described as chaos but it makes more sense to think of it as randomness or even regularity. Here's a thought experiment: imagine two perfectly insulated rooms. They are connected by a perfectly insulated door. No energy can get in or out and as long as the door is closed, no energy can go between the rooms. One of the rooms is at 100 degrees and the other is at zero degrees (Celsius or Fahrenheit, take your pick; it doesn't matter for this one). Since no energy can get in or out, the first room will stay at 100 degrees and the second at zero until the door is opened. Once the door is opened, common sense tells us that the cold room will get warmer and the warm room will get colder.
Common sense is often wrong where things like science, math, and probability are concerned (see the Monty Hall Problem and quantum mechanics), in this case it's pretty spot on. The first room has more energy than the second and energy likes to flow along a gradient from high to low. The heat from the first room will gradually seep into the second one until they are both about 50 degrees. From there they'll randomly trade particles and energy thanks to Brownian motion because they've reached equilibrium which is, for this system, the state of maximum entropy.
The Second Law of Thermodynamics says that any closed system, which is to say a system without a net positive influx of energy, will see its entropy rise. Our two rooms are a closed system that saw their entropy rise until the heat was randomly distributed between the two. That's all the Second Law says and that's all entropy is. If you add energy into the system, the entropy can go down. Say someone drills a hole into one of the rooms and pumps heat in. As long as the heat is coming in, that room will be warmer, which is a step back toward the neatly ordered state the rooms were in before and thus a decrease in entropy.
What does this have to do with uncooking an egg? I'm glad you asked.
The heat that goes into boiling an egg tangles up the proteins in the albumen, causing the egg white to go solid. There's still viable material in there; it's just all misfolded and tangled up with other molecules. Instead of being nicely organized and folded, the proteins have seen an increase in the randomness of their structure and relationships to each other. In other words, the entropy of the proteins has increased.
Weirdly, this causes the entropy of the white as a whole to decrease as it becomes a solid (remember what I said about common sense?). Solids are more regular, less chaotic structures than liquids. The energy added to the egg decreases the entropy of the whole mess, but on a molecular level, it increases the entropy of some of the component parts.
The process these scientists have developed, then, has to both increase the entropy of the solid white while decreasing the entropy of the proteins themselves to return them to their proper shapes. First of all, they use chemistry to dissolve the egg white, separating the conjoined proteins and turning it back into a liquid. Entropy increase. At this point the proteins are separate but still all misfolded, balled up, and screwy.
Next, they put the whole mess into what they call a "vortex fluid device," which is not described but I'm guessing is technical jargon for "thingamajig that done spin some liquids real darn fast." This introduces kinetic energy into the system, which translates into shear forces that cause them to untangle and spring back into their proper shapes. Entropy decrease. Bingo bango, you've got your workable protein back.
This isn't only a pretty neat discovery for people who spend lots of time and money fixing screwed-up proteins. It's a pretty neat lesson in how entropy works in every system in every corner of the universe. It's not always about heat. Sometimes it's about molecular structure. Sometimes it's about atomic structure. Sometimes it's about taking that nice, orderly Jenga tower and randomizing the pieces all over the floor. It's easy to create entropy; just open a door or drop a vase or bump the Jenga table. Heck, just wait around long enough; the universe itself is a closed system with no external source of energy, so entropy, on the grand scale, is always increasing. But to reverse entropy and reorder something out of randomness, to untangle those proteins or rebuild that Jenga tower, it takes a large influx of energy.