People preserve seasonal food to eat it later. In many tradition people use different type of food preservation method. Some of them make sauces and other make pickle to taste seasonal food later.
But in the Asian country China people preserve raw egg of chicken, duck or quail by traditional way where egg preserved by mixing it with rice husk, clay, salt, ash and quicklime for specific time interval .This time interval may vary from several weeks to several months and totally depends on the method of processing that is used by people.
People call century egg with different name few of them are millennium egg, thousand-year-old egg, hundred-year egg and reserved egg but in realty egg are not preserve for such long time. In modern time century egg not take much time as traditional method. It prepared within 10 days by putting egg that are wrapped in plastic in a solution of calcium hydroxide and sodium carbonate with salt.
Preserved egg get totally different smell and color but it consistency is something very near to hard-boiled egg. Century eggs can be consumed without further preparation or we can say direct from the shell with other dishes with ginger root pickle.
Century egg get penetrating flavor because of ammonia and hydrogen sulfide and get creamy consistency during the preservation process .The yolk of egg convert in to a dark green to grey color and white part of the egg become translucent jelly having salty flavor with a dark brown color.
Throughout this process the ph value of egg rise between 9 to 12 because of alkaline salt. Chemical processes that convert raw egg to century egg break complex protein into flavorful compounds.
Discovery of this recipe is not verifiable according to story there is a person who live in Hunan during the Ming Dynasty around 600 years ago using slaked lime from shallow pool for construction of his home while working in this pool he discovered duck eggs that preserved here naturally. He tested the egg and liked it so much and produced more egg with the addition of salt. Then people first time know about this recipe.
Most of the Century egg develops pine branches like pattern on its surface because of this some people refer this as pine-patterned egg.
There is not much difference between raw egg and century egg both has the same nutritional value except century egg contain more protein and lesser carbohydrate than fresh eggs and include vitamin A, B , B-12 and riboflavin with beneficial micro-nutrients as well. If you want to try something new than century egg definitely make you proud.