Wednesday, April 25, 2012
What We Have Forgotten?
Eggs spoil due to the introduction of airborne bacteria through the shells. Normally, the shell has a surface coating of mucilaginous matter which prevents, for a time, the entry of these harmful organisms. If this film is removed or softened by washing, the "shelf life" of the egg is reduced. Just after the turn of the century (20th Century, that is) the Department of Agriculture recommended the use of "Liquid Glass" to preserve eggs for six months or more. Liquid Glass, also known as Waterglass, is the layman's term for Sodium Silicate. Liquid Glass is odorless and colorless, and is quite inexpensive. It is widely available through chemical suppliers and is often used as a waterproofing agent. It may be obtained in powder form or in solution. To ensure the correct mixture, powder form is best. There are two principal methods which may be employed to preserve eggs with Liquid Glass.
Mix one part (weight, not volume) of sodium silicate with three parts (weight, not volume) of boiling water. Stir the solution until it has the consistency of syrup. Thoroughly clean the eggs to be preserved. The eggs should be no more than three days old when preserving. Eggs purchased in supermarkets are not suitable. Unfertilized range eggs, whose age can easily be determined, are best. Closely inspect each egg to ensure the shell is intact and that there are no hairline cracks. The eggs should be immersed in the boiling solution in such a manner as to ensure that every part of each egg is covered. Remove the eggs and place in a sterilized container to thoroughly dry. If the solution is kept at or near boiling, the preservative effect is said to be much more certain and to last much longer. Store treated eggs in a cool, dark, dry place. To use the eggs, wash them thoroughly and prepare as usual.
Mix one part (weight, not volume) of sodium silicate with nine parts (weight, not volume) of cold water. Thoroughly clean the eggs to be preserved. The eggs should be no more than three days old when preserving. Eggs purchased in supermarkets are not suitable. Unfertilized range eggs, whose age can easily be determined, are best. Closely inspect each egg to ensure the shell is intact and that there are no hairline cracks. Place the eggs to be preserved in a sterilized container (canning jars and crocks with non-metallic lids work best). Carefully pour the solution over the eggs, ensuring the eggs are not disturbed. Ensure none of the eggs crack. One cracked egg will spoil the entire container. As the eggs must be covered entirely with the solution, it is advisable to place a plate or cover over the top layer to keep them from floating. Fill container until the solution is approximately one inch over the top layer of eggs. Cover the containers and store them in a cool, dark, dry place. Eggs may be preserved for up to a year in this manner, and come out as good as fresh laid eggs. To use the eggs, wash them thoroughly and prepare as usual.
When using any chemical in the preservation of foodstuffs, there is always the potential for contamination. Sodium silicate is stable and essentially safe. When working with the dry chemical, as well as with the solution, skin and eye irritation can occur. Consult the Material Safety Data Sheet for Sodium Silicate before employing either of these two methods. Ensure neither the chemical, the solution, or the eggshell of treated eggs is ingested.
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