Century egg: Encyclopedia II - Century egg - Production

Century egg - Production

The origin of the method for creating century eggs likely came about through placing eggs in mud made from alkaline clay and water in order to preserve eggs in times of plenty. The clay hardens around the egg and likely resulted in the curing and creation of century eggs instead of spoiled eggs.

The traditional method for producing century eggs is a development and improvement from the aforementioned primitive process. Instead of using just clay, a mixture of wood ash, quicklime, and salt is included in the plastering mixture, thereby increasing the pH and sodium content of the clay mixture . This addition of natural alkaline compounds improved the odds of creating century eggs instead of spoilage and also increased the speed of the process. A recipe for creating century eggs through this process starts with the infusion of three pounds of tea in boiling water. To the tea, three pounds of quicklime (or seven pounds when the operation is performed in winter), nine pounds of sea-salt, and seven pounds of wood ash from burning oak is mixed together into a smooth paste. Each egg is then individually covered by hand, with gloves being worn to prevent the corrosive action of the lime on skin. Each egg is then rolled in a mass of rice chaff to keep the eggs from adhering to one other before placing them in cloth-covered jars or tightly woven baskets. In about three months the mud slowly dries and hardens into a crust, and then the eggs are ready to eat. The recipe makes around 100 to 150 century eggs.

Even though the traditional method is still widely practised, modern understanding of the chemistry behind the formation of century eggs has lead to many simplifications in the recipe. For instance soaking the eggs in a brine of salt and lye for 10 days followed by several weeks of aging while wrapped in plastic is said to achieve the same effect as the traditional method. This is true to the extent that egg curing in both new and traditional methods is accomplished by introducing alkaline hydroxide ions and sodium into the egg. Connoisseurs, however, argue that the use of different tea, wood ashes and local clay gives the century eggs a more delectable taste and a characteristic terroir.

Although poisonous, lead oxide is also known to increase the curing speed of century eggs and thus added to the curing mixture by some century egg producers in China, who is the world's largest producer of century eggs. Most consumers typically request for "lead-free" century eggs.

Adapted from the Wikipedia article "Production", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki