Ever wonder why??? Why are peeling fresh eggs shells so difficult? With eggs that are just a day or two old, the membrane beneath the shell sticks tightly to the shell making peeling the egg almost impossible. After a few days in the refrigerator the egg becomes easier to peel. Why is this? In fresh eggs the albumen sticks to the inner shell membrane more strongly than it sticks to itself because of the more acidic environment of the egg. The white of a freshly laid egg has a pH between 7.6 and 7.9 and an opalescent (cloudy) appearance due to the presence of carbon dioxide. After the protective coat is washed off the egg shell the egg becomes porous and begins to absorb air and loose some carbon dioxide contained in the albumen. This reduces the acidity of the egg which causes (after several days in the refrigerator) the pH to increase to around 9.2. At higher pH the inner membrane does not stick as much to the albumen so the shell peels off easier. In addition, as the egg gets older it will shrink and the air space between the egg shell and the membrane will get larger. Research shows that the reduced acidity helps with peeling. The tradeoff, however, is that in older eggs the yolk tends to move further from being centered. This happens because the white gets thinner and is less able to hold the yolk in place. The best compromise is to use eggs that have been stored on their sides in the refrigerator for 7 to 10 days.
Posted on: Sun, 10 Nov 2013 17:18:20 +0000
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