Century egg
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Image:Centuryegg-32.jpg The century egg, also known as preserved egg, thousand-year egg, thousand-year-old egg; (Template:Zh-cp; lit. skin (pí) + egg (dàn)) or (Template:Zh-cp; lit. pine-patterned egg) is a Chinese food made by preserving duck or chicken eggs in a mixture of clay, ash, salt, lime, and rice straw for several weeks to several months, depending on the method of processing. The yolk of the egg is concentrically variegated in pale and dark green colors while the egg white is dark brown and transparent like cola.The yolk is creamy with a strong aroma and an almost cheese-like flavor. The egg white has a gelatinous texture similar to cooked egg white, however with very little taste. Some eggs have patterns near the surface of the egg white likened to pine branches.
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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 extremely 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. Some have even used zinc as a replacement which is an essential mineral in our diets.
Use
Image:Centuryeggwithpickledginger.jpg A typical way of eating the preserved egg is with rice congee, as in lean pork and preserved egg rice congee (Template:Zh-cp). It is cut into quarters or eighths, and the seasoned marinated lean sliced pork is boiled with the eggs until the meat is cooked in the rice congee. Fried bread known as youtiao is commonly eaten with congee. As an hors d'œuvre, the Cantonese wrap chunks of this egg with slices of pickled ginger root, whereas the Shanghaiese mingled chopped century eggs with chilled tofu. The Taiwanese like to eat them on top of cold tofu with katsuobushi, soy sauce, and sesame oil in a similar style as Japanese Hiyayakko. They can be also eaten alone as a side order. They are also used in a dish called old-and-fresh eggs, where chopped preserved eggs are combined with (or used to top) an omelette made with fresh eggs.
People generally eat century eggs uncooked and accompany the dish with Ginger Soy sauce etc. Tofu can also accompany century eggs. Those who do not like century eggs can eat tofu on its own or with other ingredients. Mobile hawkers may sell pieces of century egg on sticks with slices of pickled ginger. This can be eaten raw or boiled.
On special events, like wedding banquets or birthday parties, a first course platter of sliced barbequed pork, pickled baby leeks, sliced abalone, pickled Julienned carrots, pickled julienned daikon radish, seasoned julienned jellyfish, sliced pork head cheese and the quartered century eggs is served. This is called a lahng-poon in Cantonese, or a cold dish.
Myth
According to a persistent myth, century eggs are or once were prepared by soaking eggs in horse urine. This is not true since urine is usually acidic or very weakly alkaline, and the myth may arise from the ammonia smell created during some production processes.
Literary References
In Amy Tan's The Hundred Secret Senses, one of the characters is seen making this dish and burying it underground in her backyard.
References
- Mabel Ho (1988) Chemistry Potpourri : Unlocking Chemistry through Investigations, Singapore Science Centre
- H.C. Hou (Hou Xiangchuan), (1981) "Hunger and technology - Egg preservation in China", The United Nations University Press Food and Nutrition Bulletin Chapter 3, 3(2), ISBN 92-808-0254-2
- Taiwan Livestock Research Institute and Philippine Council for Agriculture (2001) Enhancing the Value of Eggs: How to Make Balut and Century Eggs Retrived Dec 1, 2005