salmonella is killed instantly when subjected to a temperature of 160°. An egg (white and yolk) requires a temperature of up to 158°F before it sets properly. The white alone requires a somewhat lower temperature before it coagulates, usually in the 140° to 150° range. These temperatures are only slightly less than what is required to destroy all of the harmful bacteria that may be present, so heating eggs to 160° F should not cause eggs to be overcooked, unless they are held at that temperature (or higher) for an extended period.
First, have you ever had a hard boiled egg with a greenish grey yolk? Chemically, there are a few interesting geeky things going on here. When cooked, sulfur is released from the white of the egg, which combines with hydrogen ions to form hydrogen sulfide. And when the hydrogen sulfide gas encounters iron on the border of the yolk of the egg, it forms iron sulfide. That iron sulfide is the icky green-grey gunk on the outside of your yolk. All three of these chemical reactions that help produce iron sulfide are improved in efficiency the hotter and longer you cook your egg.
The second cool geeky thing about cooking eggs is why the white hardens the way it does. Raw egg white is full of tightly coiled proteins. They’re just hanging out there, not doing much. This is why you can see through raw egg white: the proteins aren’t interacting with each other; they’re mostly suspended. (Think of peas suspended in clear jello: if you hold up a block of it you can still (mostly) see around the peas.)
But start to cook egg white, and those proteins unwind into lose strands. The loose strands start interacting with each other (imagine filling a drawer full of loose strings; now mix them up, and then try to get them untangled.) Keep cooking the egg white (mixing the drawer full of strings), and the bonds (knots) get more numerous and tighter. This process squeezes water out from between the proteins and makes the white more rubbery. The excess water diffuses through the shell as steam (another symptom of overcooked eggs is when they crack from the prodigious steam buildup.) [...]
Torr, a unit of pressure. One torr was originally defined as the pressure exerted by a millimeter depth of mercury (mmHg), then as 1/760 of a standard atmosphere.
Because the standard atmosphere is now a defined quantity in the SI system of units, the torr is hence defined as exactly 101325 / 760 pascals. Although the torr is still in common use in low-pressure engineering, the pascal is now the recommended unit of pressure.
« Older The Number 23 has a movie.... | We're all familiar with Peruvi... Newer »
This thread has been archived and is closed to new comments
Buy a Shirt