MadSci Network: Chemistry |
Dear Roger,
You are correct in thinking the connection between bug guts on your car and egg
in your pan is protein. Specifically, the proteins are hydrophillic
proteins.
When the insects are alive, they have a liquid body cavity containing hemolymph.
Hemolymph is their version of blood. Both hemolymph and blood contain
hydrophillic proteins. Hydrophillic proteins are proteins that
dissolve in water. (If the proteins in blood became solid, they would
clog up all of the blood vessels. This is analogous to what happens in heat
stroke.)
Eggs, as you know, are full of proteins. In their natural "raw" state, those
proteins are also dissolved in water. Egg proteins are also hydrophillic.
When hydrophillic proteins are cooked, two things happen. First, they become
denatured. Protein denaturation simply means that the protein's shape is
changed. Imagine a wire coat hanger. If it were a hydrophillic protein being
cooked, it would untwist itself into a straight metal wire. Its special
coat-hanger function would be ruined. In this case, the proteins also lose
their special hydrophillic nature, and can no longer dissolve in
water. Water can only dissolve hydrophillic proteins, and the cooked
proteins are no longer hydrophillic.
Secondly, when you cook an egg in your pan, or a bug on your car, the water is
boiled away. When all of the water is gone, the denatured proteins are left
smashed into every tiny nook and cranny of your pan and car. This makes it very
difficult to pry them loose with scrubbing.
What can help you scrub off the egg and bug guts? Soap! How does soap work?
Soap is an emulsifier. Emulsifiers are chemicals that break up fats, and
make them somewhat hydrophillic.
In eggs and bug guts, there is also some fat. When the proteins are getting
smashed into every nook and cranny, there is some fat that gets smashed in there
too. Using soap, the fat is broken up, which allows the clot of proteins to be
washed away.
Of course there is fairly little fat in eggs. And some insects have more fat
than others. So often times, it's going to take brute force to remove those
cooked denatured proteins!
For more information on how proteins denature I recommend to you two other MAD
Scientist essays. Jill
Irvin, a food scientist, explains denaturation in a thorough, easy to
understand essay. Alvan
Hengge, a chemist, explains the molecular biology of denaturation, and gives
some links to other websites with information on the process.
Thank you for your question, and good luck scrubbing!
John
Try the links in the MadSci Library for more information on Chemistry.