Eggshells

Whether they are white or brown or speckled is immaterial to the cook. What does matter is that they are porous. One consequence of this is that eggs may absorb unwanted odours, a risk to which textbooks often call attention but which in practice seems to be slight. Another is that the carbon dioxide which begins to be formed within the egg as soon as it is laid can get out. Loss of carbon dioxide increases alkalinity and causes a slight diminution in the protein content of the egg. Egg processors can prevent this by dipping their cleaned eggs in a special colourless and tasteless machine oil that seals the pores of the shell. They, no doubt unwittingly, make it impossible to execute some kinds of egg cookery which are typical of the Middle East, notably ‘hamine’ eggs, in which whole eggs are simmered overnight, very gently, with oil and onions, whose flavour permeates the contents. A more exotic example is provided by Œufs à la constantinopolitaine, a recipe given by Mrs Leyel and Olga Hartley (1925), which calls for cooking eggs in their shells very slowly for at least twelve hours in a mixture of olive oil and Turkish coffee. The mixture eventually penetrates the shells, making the whites amber and the yolks orange, and imparting a flavour of chestnuts. The best way, however, to delay loss of condition is refrigeration.