Saturday, May 19, 2012

Century Egg


Century egg, also known as preserved egg, hundred-year egg, thousand-year egg, thousand-year-old egg, and millennium egg (or Pidan in Mandarin), is a Chinese cuisine ingredient made by preserving duck, chicken or quail eggs in a mixture of clay, ash, salt, lime, and rice hulls for several weeks to several months, depending on the method of processing. Through the process, the yolk becomes a dark green, cream-like substance with a strong odor of sulphur and ammonia, while the white becomes a dark brown, transparent jelly with little flavor.[citation needed] The transforming agent in the century egg is its alkaline material, which gradually raises the pH of the egg to around 9, 12, or more.This chemical process breaks down some of the complex, flavorless proteins and fats, which produces a variety of smaller flavorful compounds.

Some eggs have patterns near the surface of the egg white that are likened to pine branches.


 
The origin of the method for creating century eggs likely came about through the need to preserve eggs in times of plenty by coating them in alkaline clay, which is similar to methods of egg preservation in some Western cultures. The clay hardens around the egg and resulted in the curing and creation of century eggs instead of spoiled eggs.

Myth
Picking up century egg by Mandru in Incheon.

According to a persistent myth, century eggs are, or were once, prepared by soaking eggs in horse urine. The myth may arise from the pungent odor of ammonia given off by century eggs, which is reminiscent of urine.Horse urine itself, however, is only slightly basic, ranging in pH from 7.5 to 7.9. Though human urine left standing can reach a maximum pH of around 9.4—the same as a 1-molar solution of ammonia—it is still less than that produced by mixing quicklime (calcium oxide) or wood ash in water.