Dear Straight Dope:
This may be a simple one for you but it has me bugged. Why is it easy to remove the shell from some hard boiled eggs (peels loose without sticking) and really annoying on others? Is the variable in the egg or the preparation?
SDStaff Ken, Dex, and Terey reply:
This from Learn2.com, in their tutorial on hard-boiling eggs (See? It’s all out there on the ‘net, if you know where to look):.
Immediately soak the eggs in cold water. This will stop the eggs from cooking by their own heat, and will also help with peeling them. Keep them in the cold water for 30 seconds or so, or until you can handle them without shouting “Ow, ow, ouch!!” and passing them hurriedly from hand to hand. While they’re in the cold water, a layer of steam develops between the shell and the egg white. The steam makes peeling an egg much easier. (Italics mine)
Additional comments from The Joy of Cooking:
Much discussion swirls around the best way to peel a hard-boiled egg. Very fresh eggs (less than 3 days old) are the most difficult to peel. The older an egg, the larger the air cell, and the neater it peels. Thoroughly chilling hard-boiled eggs before peeling helps by firming the white. Holding an egg under a stream of water as you peel removes any bits of broken shell.
Some cooks advocate a two-step method that involves plunging the cooked egg into ice water for two minutes, then reboiling it for exactly 30 seconds and peeling it immediately.
The Joy of Cooking also comments that eggs should not actually be boiled; they should be put in simmering water and cooked gently. Higher heat overcooks the proteins, leaving the egg white tough and rubbery. Overcooking may also cause a greenish black rim to form between the yolk and the white. This is harmless but yucky when it comes to gourmet cooking.
We looked in several cookbooks, all of which said that when you take the eggs off the heat, you plunge them immediately in cold water to halt the cooking, as well as to help with the peeling.
SDSTAFF Terey adds:
Something that also seems to help, for some reason, is to bang the eggs back and forth in the pan while you’re running them under the cold water, then peeling them as soon as they’re cool enough to touch. Of course, this doesn’t work if you need to have the shell intact for whatever reason. It is true, too, that the eggs should be at least a few days old to be easiest to peel.
Send questions to Cecil via firstname.lastname@example.org.
STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL'S ONLINE AUXILIARY. THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU'D BETTER KEEP YOUR FINGERS CROSSED.